JP2016146576A - Measuring method and measuring tool and correction method of reproduction characteristics of earphone and application program of measurement and application program of correction - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple method for measuring and correcting various characteristics of a wide variety of earphones full of market.SOLUTION: Outputs of sound of the left and right earphones are coupled, a measurement signal is reproduced by one of the left and right earphones, the reproduction sound is detected by the other earphone, and then its electromotive force is analyzed, thus calculating the reproduction characteristics of the earphones. The impact of voltage drop of a ground line shared by the left and right earphones is subtracted predictively. Furthermore, the specificity due to acoustic coupling of the left and right earphones is corrected, thus determining the filter characteristics for converting from the reproduction characteristics of the earphones to the expected reproduction characteristics by means of the filter. That filter characteristics are built in a player.SELECTED DRAWING: Figure 1

Description

In the following text, including the following description and claims, the following terms are defined:
The terms defined in the claims are the same in the specification.
In the following description, the symbol {} is used mainly for the description term in order to define the description more accurately so that the scope of interpretation does not vary, and the description in {} is the description outside {}. Shall have priority over.

Reproduction characteristics measurement of earphones Reproduction characteristic correction of earphones {Mobile terminal} with a music reproduction function called a portable personal computer or a smart phone has a powerful calculation processing function, a large amount of memory and an acoustic signal input / output function, or a microphone Input function}, which are sufficient functions for measuring the reproduction characteristics of the earphone.
Acoustic signal processing Smartphone music player signal processing mechanism Least squares fast Fourier transform

First, the sound quality of each type of earphone on the market is significantly different.
Second, many users do not know what the absolute standard sound quality is.
Third, the user can correct the reproduction characteristics of the earphones {subjective, individual auditory characteristics, unique sound quality for each song, and an authorized method that does not depend on the earphone wearing state} There is no.
Fourth, each type of music player has a characteristic sound quality selection function, and it is difficult for many users to intentionally select an expected sound quality.

First, the sound outlets of the pair of left and right earphones are acoustically coupled so that one side functions for reproducing the {measurement signal} and the other functions for detection as a microphone.
{Measurement signal} is reproduced from the {portable terminal}, input to the terminal of one earphone, and the electromotive force generated at the terminal of the other earphone is captured.
Second, the voltage drop of the lead wire shared by the left and right earphones is corrected, and the {coupling characteristics} of {detection-side earphones} are calculated purely due to acoustic coupling.
Thirdly, the correction of the specificity of {acoustic attachment} in {coupling characteristics} and the method of using left and right earphones for reproduction and detection are added.
Based on the above results, the reproduction characteristics specific to each earphone are calculated.
Fourth, a parameter group of a filter that approximates the inherent reproduction characteristic of the measured earphone to {expected earphone reproduction characteristic} is obtained.
Fifth, by embedding the obtained parameter group in the filter for actual operation, a filter that corrects the peculiarity of a specific earphone to {expected earphone reproduction characteristics} is configured.
Sixth, player playback data is input to the filter group, and a playback signal having a sound quality approximate to {expected earphone playback characteristics} is obtained from the output of the filter group.
Seventh, the playback function, microphone function, calculation function, and display function of the portable terminal are used.

First, the reproduction sound quality can be corrected so that {the sound quality of the earphones owned by each user} can be reproduced with a certain level of sound quality by each user's own hands.
Second, the sound quality of the earphones corrected so as to achieve the sound quality of {expected earphone reproduction characteristics} facilitates selection of the sound quality preferred by each user based on a certain level of sound quality.

These are explanatory drawings of one Example of the acoustic coupling of an earphone on either side. These are explanatory drawings of one Example of the acoustic coupling of an earphone on either side. These are explanatory drawings of one Example of the acoustic coupling of an earphone on either side. FIG. 4 is an explanatory diagram when the left and right earphone lead wires share a part of the ground line. These are explanatory drawings of the example of a connection of an earphone which is possible when the portable terminal device has left and right earphone outputs and one microphone input terminal. These are explanatory drawing of the example of a connection of an earphone possible when a portable terminal device has a right and left sound output and a right and left microphone input terminal. These are explanatory drawing of an example of {structure and process} which measures and calculates the reproduction characteristic of an earphone. These are explanatory drawing of an example of {structure and process} which measures and calculates the reproduction characteristic of an earphone. Is based on the measurement result of the reproduction characteristics of the earphone, {an example of how to determine the parameter of the filter} for correcting to the target characteristic, and {the filter having the determined parameter, Explanatory drawing of {structure and process} of an example of a method for correcting the characteristics. Shows an example of acoustic coupling measurement and correction of voltage drop for an earphone with a strong habit of reproduction characteristics. These are characteristic examples for each process from calculating the earphone coupling characteristics to calculating the earphone reproduction characteristics. Is a reproduction characteristic obtained by converting the obtained earphone characteristic into {expected earphone reproduction characteristic}. Is the inspection data of the earphone production process used in the measurement example. Is a comparison of {pure resistance} and {impedance characteristics of earphones including lead wires}

{Application program of portable terminal device for measuring earphone characteristics}, {Coupling attachment}, and {Connection adapter for measurement}.

Supply {Application Program}, {Combination Attachment} and {Measurement Connection Adapter} to the consumer market as products.

FIG. 1 is an explanatory diagram of an embodiment of acoustic coupling of left and right earphones.
The state where the left and right earphones are acoustically coupled with the earpiece of a general earphone removed is shown.
1 is {reproducing earphone}, 2 is {detecting earphone}, 3 is {combined attachment}, 4 is {measurement signal}, and 5 is the reproduction sound of {reproducing earphone} is transmitted to {detecting earphone} Route 6 is the electromotive force of the detecting earphone.

{Combination Attachment} has a role of acoustically coupling the left and right earphones.
The reproduced sound from the {reproducing earphone} is transmitted to the diaphragm of the {detecting earphone} via the sound outlets of both earphones. The vibration of the diaphragm generates an electromotive force. The relationship of the electromotive force to the {measurement signal} depends on the conversion characteristics of the earphone. Although it is a rough tendency, the electromotive force obtained by acoustically coupling the left and right of the earphone, that is, {actual acoustic coupling signal}, is proportional to the square of the reproduction characteristic of the earphone. Therefore, by adding a correction that {obtained {relation of {acoustic coupling signal} to {measurement signal}}, that is, a square root of intensity for each frequency of {coupling characteristic}, reproduction characteristics of an actual earphone are added. A measurement result close to can be obtained.

A specific calculation formula for correction has a characteristic unique to each measurement system, and it is the essence of the present invention to apply correction to the specific characteristic. Since the detailed definition of each unique property is not the essence of the present invention, a description thereof will be omitted.

There are the following two largest factors to be corrected with respect to {acoustic coupling detection signal}.
First, since the same earphone is used synergistically on the playback side and the detection side in the measurement system,
The square of the characteristic of the earphone is reflected in the measurement result.
Second, the size and shape of the coupling attachment.

FIG. 2 is an explanatory diagram of an embodiment of acoustic coupling of left and right earphones.
A state in which the left and right earphones are acoustically coupled in a state where the earpieces of general earphones are attached is shown.
The same number as FIG. 1 is the same function. 101 and 201 are left and right earpieces, respectively, and 31 is a joint attachment.
The factor to be corrected for {terminal detection signal} is the same as in FIG.

FIG. 3 is an explanatory diagram of an embodiment of acoustic coupling of the left and right earphones.
A state in which the left and right earphones are acoustically coupled in a state where the earpieces of general earphones are attached is shown.
3, the same number as FIG. 1 and the same number as FIG. 2 have the same functions. 32 is {{sound absorbing piece}} inserted in the tube of {{connection attachment}}. Inside the {joint attachment}, acoustic energy is transmitted from one to the other, but the reflection of sound waves occurs depending on the material and shape dimensions. The reflection of the sound wave affects the measurement result {coupling characteristic}, and causes an error. Even in the actual use state where the earphone is worn on the ear, there is some reflection of sound waves in the transmission path, and the details of the characteristics are complicated. It is also affected by the type of earphone and the insertion state of the earphone. It is not easy to finely correct the influence of such reflected waves, and it is not a factor that greatly affects the overall sound quality. However, it is desirable that reflection is suppressed in the sense of reducing measurement errors. As shown in FIG. 3, providing an appropriate sound absorbing material inside the coupling tube is a simple and effective means.
The above corresponds to claim 6.

FIG. 4 is an explanatory diagram when a part of the ground line of the left and right earphones is shared.
The same number as FIG. 1 is the same function.
11 and 21 are branched left and right earphone leads, 7 is the body part of the earphone plug, 10 is the ground terminal of the earphone plug, 12 and 22 are the hot sides of the left and right earphone terminals, and 8 is the left and right earphones, respectively. The branch point of the common part of the ground lead wire, 9 is the part sharing the ground line of the left and right earphones. The majority of earphone plugs on the market have three common ground terminals. The length of the portion sharing the left and right ground lines also varies depending on the type of earphone. Some types do not have a shared portion of the ground line. In general, since the left and right ground lines are shared in the wiring inside the earphone plug and the portable terminal, strictly speaking, it is considered that there is a shared part of the ground lines of all the earphones.

In the shared portion of the ground line, a voltage drop due to the current flowing through the {playback earphone} occurs. The voltage drop in the shared part of the ground line is added to the electromotive force due to the pure acoustic coupling of the detecting earphone. Since the electromotive force of the detection-side earphone is small, the voltage drop at the shared portion of the ground line greatly affects the measurement error, so it needs to be precisely removed.

FIG. 5 is an explanatory diagram of the connection between the earphone jack and the earphone plug when the portable terminal has left and right sound outputs and one microphone input terminal.
1 and 4 are the same functions. GND is ground, L is left side, R is right side, MIC is microphone input, 7 is earphone plug, 71 is relay connection for measurement between earphone plug and earphone jack, 72 is earphone jack, 91 is sharing the left and right ground lines Parts 10, 10, and 22 are the earphone plug ground terminal, left terminal, and right terminal, 111 and 211 are the parts where the ground wires are branched and connected to the ground terminals of the left and right earphones, and 112 and 212 are each It is a lead wire on the hot side of the left and right earphones.
71 relays the connection of the earphone jack of the portable terminal from the earphone plug. It has a role for connection conversion that converts the connection of the terminal to measure the characteristics of the earphone.

The GND of the portable terminal is connected to the shared GND terminal of the earphone.
The L side of the mobile terminal is connected to the L side hot terminal of the earphone, and supplies {measuring signal} to the {playback side earphone}.
The wiring is changed so that the MIC input of the portable terminal is connected to the R side hot terminal of the earphone, and the electromotive force of the {detection earphone} becomes the MIC input.
In the shared ground line portion 91, a voltage drop occurs due to the current flowing through the {playback earphone}, and is added to the electromotive force generated by the right earphone due to the voltage drop, and measured at the right earphone terminal {terminal detection signal} Become.

FIG. 6 is an explanatory diagram of connection of earphones when the portable terminal has left and right sound outputs and left and right microphone input terminals.
The same reference numerals as those in FIG. 5 in FIG. 6 denote the same functions. The internal wiring of the connection conversion plug jack 71 is different from that shown in FIG. Reference numerals 711 and 712 denote resistors for dividing the measurement signal. The divided {measurement signal} is connected to the L side of the sound input terminal of the portable terminal. The R side is connected to the {detection side earphone} as in FIG. By this method, the voltage proportional to {measurement signal} and {terminal detection signal} generated by {measurement signal} are not affected by the time delay of the digital signal processing system and the degradation of the characteristics of the analog system, Both will be measured under the same conditions. However, depending on the device, the function of converting to the left and right digital codes may have a time difference corresponding to a half cycle of sampling. Therefore, as described in claim 3, Hxmin (t) must be verified by trying a time difference of a half cycle of sampling.

FIG. 7 is an explanatory diagram of the structure and process for measuring and calculating the reproduction characteristics of the earphone.
The present invention is applied to a portable terminal having a monaural microphone input terminal as shown in FIG.
The mobile phone which is used to correct the {voltage drop of the ground line of the earphone described in claim 2} and {transfer characteristic of the coupling attachment} and {speciality by using the left and right earphones on the reproduction side and the detection side}. A block diagram of the structure and process of an application program that functions on the OS of the terminal is shown.
In the portable terminal, the time series code data to be reproduced is transferred to the output function in the acoustic signal reproduction process, and an indefinite delay of about 100 msec to 3 sec occurs. It is necessary to calculate Hxmin (t) by trying the time difference.
In Fig. 7, since Fi (t) is time-series encoded data, there is an uncertain time difference from 100msec to 3sec with Fec (t). Buffer memory is required.
If the time difference between the two recorded signals to be compared for the calculation of the {combining characteristics} is long, it takes a few seconds, and it is influenced by the size of the data buffer memory that depends on the operating status of the mobile terminal, the model, and the playback music. Since the delay time is greatly influenced, it takes time to specify the time difference s defined in claim 3. However, since the measurement time is faster than human movement, there is no problem in practical use.

The same reference numerals as those in FIG. 5 in FIG.
Fi (t) is time-series encoded data in which white noise that is {measurement signal} is recorded,
Fec (t) is time-series encoded data in which {terminal detection signal} is recorded,
DELAY is a read relative address corresponding to the time of the time-series encoded data corresponding to the time difference s defined in claim 2. The time difference of half the sampling period, which is the smallest unit of s, is obtained from the previous and subsequent data.
k is the proportionality factor,
{k, s} CONTROL is a function that determines kmin and smin that satisfy Hxmin (t) described in claim 2 by operating k and s, s is in the range of 0.1 to 3 seconds,
DIFF1 is a function for generating the difference signal Fec (t) −k * Fi (ts) described in claim 2;
FFT is a fast Fourier transform function for finding {coupling characteristics}
COMP-DATA is a correction characteristic of {specificity of {joint attachment} and {speciality of transfer characteristic of using left and right earphones for reproduction and detection}, as described in claim 4;
MODIFY receives COMP-DATA and corrects the intensity for each frequency in {coupling characteristics}
SQR is a function for obtaining the square root of the intensity corresponding to each frequency of the characteristic output by MODFY, and FFT, COMP-DATA, MODIFY, and SQR correspond to {joint attachment correction characteristic calculation procedure} described in claim 4. .
EARPHONE-CHARA is {earphone characteristics before correction}.
D-> A is the digital-analog converter
D <-A is the analog-digital converter

FIG. 8 is an explanatory diagram of the structure and process for measuring and calculating the reproduction characteristics of the earphone.
The present invention can be applied to a portable terminal having a stereo microphone input terminal as shown in FIG.
The correction of {the voltage drop of the ground line of the earphone described in claim 3}, {the transfer characteristic of the {connection attachment}} and {the speciality by using the left and right earphones on the reproduction side and the detection side} is applied. A block diagram of the structure and process of an application program functioning on the OS of the mobile terminal is shown.
{Coupling characteristics} Since the time difference between two recording signals to be compared for calculation is at most half the sampling period, the calculation time of the voltage drop at the common part of the ground line of the earphone is short.
Since the conditions for generating the two data to be compared are aligned, the influence of the error of the analog system inside the terminal is extremely small compared to FIG.

The same numbers in FIG. 8 as those in FIGS. 6 and 7 have the same functions.
WHITE-NOISE is {noise signal} white noise data,
Fi (t) is time-series encoded data that records a signal obtained by dividing the voltage of the earphone terminal of {playback earphone},
Fec (t) is time-series encoded data in which {terminal detection signal} is recorded,
DELAY is a read relative address of time-series encoded data corresponding to the time difference s defined in claim 3. The time difference of half the sampling period is obtained from the previous and next data.

FIG. 9 is an explanatory diagram of the structure and process of an embodiment for correcting the reproduction characteristics of the earphones measured and calculated to the desired reproduction characteristics.
FIG. 9 shows an example of a correction method using a filter corresponding to claim 4, but the type and specific configuration of {correction filter} are not the essence of the present invention.

FIG. 9A is a block for reproducing sound as a player. An example of the structure and process of a function in which five secondary filters correct the earphone-specific reproduction characteristics to {expected earphone reproduction characteristics}. Indicates.
MUSIC-DATA is the music data to play,
Each of eq1, eq2, eq3, eq4, and eq5 is a secondary filter, and the parameters that determine the characteristics of each filter are determined by the block shown in FIG. 9B. PARAMETER-SET is a parameter group that determines the characteristics of each filter.
Each of eq1, eq2, eq3, eq4, and eq5 is responsible for the variation range of the characteristics of {super bass, mid bass, mid treble, treble, super treble}. The variation range is an example, and the variation range is not the essence of the present invention.
The output of eq5 is time-series encoded data obtained by correcting the peculiarity of the reproduction characteristic inherent to the earphone to the intended reproduction characteristic.
OUTPUT is a function to reproduce time-series encoded data in real time,
EARPHONE is an earphone,
SOUND is the playback sound.

In the description of FIG. 9, the number of filters is five. However, in general, the characteristics specific to the earphone are affected by the environment in which they are used, and are quite complicated at a fine level. Correction of these fine characteristics is not an important factor for normal listening. The difference in sound quality can be evaluated by dividing it into the above five bands, or at most seven bands. The number of filters is not the essence of the present invention. The number of earphones is generally an arbitrary plural number, but practically, at least three and at most seven function sufficiently in practical use.
The sound quality of the playback sound SOUND is the sound quality corrected so that the special characteristics of the earphones are brought closer to the {expected earphone playback characteristics} by eq1, eq2, eq3, eq4, eq5.
There is a problem as to whether the sound quality corrected to {expected earphone reproduction characteristics} matches the user's preference. It is not the essence of the invention of the present invention that the output of eq5 is an earphone output or that the user can select a desired sound quality to the output of eq5.

FIG. 9B is an explanatory diagram of the structure and process of the function for determining the parameter group of the filter group from eq1 to eq5 in FIG. 9A and obtaining the correction characteristic of the earphone.
EARPHONE-CHAR. Is an intensity characteristic with respect to the frequency of a specific earphone obtained by the function shown in the embodiment of FIG. This characteristic is a two-dimensional pattern of intensity with respect to frequency, which is input to EQ1.
Let {EQ simulator} be a function for correcting a filter with a pattern of intensity characteristics with respect to frequency instead of signal processing.
EQ1, EQ2, EQ3, EQ4, and EQ5 are {EQ simulators} each having a limitation on the variable range of parameters for correcting the special characteristics of {joint attachment}.
Five {EQ simulators} correspond to the five filters in FIG. 8A, and the variable range of each {EQ simulator} is the same as the variation range of each filter in FIG.
The output of EQ5 is obtained by correcting EARPHONE-CHAR. By connecting 5 EQ simulators in series.
REFFERENCE is the {expected earphone reproduction characteristic} described in claim 1.
The definition of the characteristic of {expected earphone reproduction characteristic} is not the essence of the present invention.
DIFF2 is a comparison function between {EQ5 output and REFFERENCE}. The comparison result is the degree of difference in the intensity for each frequency in all frequency bands.
EQ-CONTROL adjusts and determines the parameter group of five {EQ simulator} to minimize the degree of difference between {EQ5 output and REFFERENCE}. The parameter group can be expressed by three parameters: center frequency, Q value, and gain of each {EQ simulator}.
The parameter group determined by EQ control is transferred to PARAMETAER-SET as the parameters of equalizers eq1 to eq5 that control the actual signal processing in Fig. 9 (a).

Although it is theoretically possible to obtain an accurate correction characteristic by multiplying {expected earphone reproduction characteristic} by {reciprocal of measured reproduction characteristic of earphone}, in general, as a filter for actual operation, Since the scale is large and there are instability factors in the calculation process and there is no solution, it is necessary to deal with the judgment function and is not practical. The method of FIG. 9 is a simple and practical method.

FIG. 10 is a measurement example of acoustic coupling of an earphone having a wrinkle strong in reproduction characteristics.
This is a characteristic of an actual measurement value as a result of actual operation of {Voltage drop correction calculation procedure} of claim 3.
The horizontal axis represents frequency, and the vertical axis represents signal or coupling strength at each frequency. The intensity of the vertical axis of each graph is not clearly defined as 0 dB, but is an expression value that does not correct the absolute scale in each process of measurement results and calculation results, and evaluates the relative relationship between characteristics It is a characteristic to do.

01 is {measurement signal},
02 is an actual measurement example of the {terminal detection signal} of the test earphone by acoustic coupling when there is a voltage drop of the shared ground line,
03 is an example of actual measurement of {terminal detection signal} of the test earphone when there is no shared ground line,
04 is an actual measurement example of the {coupling characteristic} of the test earphone by acoustic coupling when automatic correction of the voltage drop of the shared ground line is applied by the method described in claim 3. However, since the resolution of the time difference is used as the sampling period, an error corresponding to a half period is included.
05 is a frequency characteristic with the transfer characteristic of {joint attachment} corrected for 04,

The slight difference between 03 and 04 below 8kHz arises from the measurement error and can be ignored in the light of correction of the characteristic of the earphone, which is the essence of the present invention.
The difference of around 10dB between 8 and 03 between 03 and 04 is generated from the measurement system. This is due to the measurement by a consumer use notebook PC not designed as a measuring instrument, and is mainly an error due to {a phase difference of half the sampling period that occurs when the left and right signals are digitally converted}.
In this frequency band, the difference between the standard measuring instrument and the actual use state is large, and the variation in characteristics depending on the wearing state of the earphone is very large, so that the correction based on the measurement result is less important.
For the above reasons, it can be determined that the measurement result of {coupling characteristics} by the method of claim 3 is practically sufficient.

FIG. 11 shows the characteristics for each process from the measurement result of the coupling characteristics of the left and right earphones to the calculation of the reproduction characteristics of the earphones.
It is an actual measurement value as a result of actual operation of {square root calculation procedure} described in claim 4.
04 is a frequency characteristic of a signal obtained by automatically correcting the voltage drop of the shared portion of the ground line from the {terminal detection signal} on the detection side, and is the same as 04 in FIG.
05 is the frequency characteristic of the signal corrected for the transfer characteristic of {joint attachment} relative to 04,
06 is the square root of the intensity on each frequency axis of 05.
The frequency characteristics of the signal obtained by {determining the square root of the intensity on each frequency} of the measured value of {coupling characteristics} are approximated to the characteristics of the factory ear inspection of the earphones to be tested. An earphone characteristic measurement result calculated by an example of {Earphone reproduction characteristic calculation procedure} of correcting output characteristics} is shown.

FIG. 12 shows reproduction characteristics obtained by converting the characteristics of the obtained earphones into {expected earphone reproduction characteristics}.
Reference numeral 07 denotes reproduction characteristics of the test earphone using white noise as an input and the output of the {correction filter} in which the {correction parameter group} of the test earphone is embedded as a reproduction signal.
FIG. 6 is a connection diagram showing measurement and calculation according to the embodiment shown in the block diagram of FIG. 8, and calculation and correction of the reproduction characteristics of the test earphone with the five secondary filters shown in the block diagram of FIG. Reproduction characteristics.
{The device that measured the characteristics of Fig. 12 and the device that measured the characteristics of Fig. 13 are of different types}, {Accuracy due to the five correction filters} and {the measurement system's peculiarity This indicates that the strong characteristic of the original wrinkle has been greatly corrected as indicated by the characteristic 071 in FIG. 13 or 06 in FIG.

Fig. 13 shows the test results of the earphone production process used in the measurement example.
071 is the frequency characteristic.
Generally, since it is measured according to a standardized industrial standard, it may be considered that it represents an intrinsic characteristic of the earphone.
The inspection results in the production process do not necessarily represent the absolute characteristics of the earphones, and the characteristics of 071 should be read as insufficient accuracy in the acoustic coupling system of the measuring instrument in the range of 5000 Hz or higher. Can do.
It is a practical technique to design the calculation process of the {earphone reproduction characteristic calculation procedure} so that the result of {earphone reproduction characteristic calculation procedure}, that is, the frequency characteristic 04 of FIG. 9 approaches the frequency characteristic 071 of FIG. .

FIG. 14 is an actual measurement example of frequency characteristics comparing the electric impedance of the earphone and the impedance of the pure resistance. 08 is the frequency characteristic of the voltage across the pure resistor due to constant current white noise, and 09 is the frequency characteristic of the voltage at the earphone terminal due to constant current white noise. Both are flat in the acoustic frequency band, and the electrical impedance of the earphone can be calculated as a pure resistance.
Therefore, it is data that supports the fact that the error calculation which is a practical problem is not generated in the method of actual measurement calculation by regarding the lead wire of the earphone and the voice coil of the earphone of claim 2 and claim 3 as a pure resistance.

Claim 1 relates to a basic method of the present invention, and is based on a combination of the following methods.
Use {joint attachment}.
The left and right earphones are joined with {joint attachment}.
Sound signal is detected by playing {measurement signal} from one side and microphone as the other side.
Corrects the voltage drop at the part of the earphone lead wire sharing the ground wire.
Correct the transfer characteristics of {joint attachment}.
Correction of transfer characteristics where left and right earphones are used for playback and detection.
Correction of measured earphone characteristics to {expected earphone reproduction characteristics}

Claim 2 is one embodiment of the {voltage drop correction calculation procedure} described in claim 1 and relates to a specific method that can be applied when the microphone input of the portable terminal is monaural. Depending on the combination.
Play {measurement signal} from {playback earphone}.
Measure {terminal detection signal} of {detection side earphone} with monaural microphone input.
{Coupling characteristic} is calculated from time-series code data of {measurement signal} and {terminal detection signal} time-series encoded data

Claim 3 is an embodiment of the {voltage drop correction calculation procedure} described in claim 1 and relates to a specific method that can be applied when the microphone input of the portable terminal is stereo. Depending on the combination.
Play {measurement signal} from {playback earphone}.
Measure {terminal detection signal} of {detection side earphone} on the R side of stereo microphone input.
Measure the divided signal of {measurement signal} on the L side of the stereo microphone input.
The {coupling characteristic} is calculated from the time-series encoded data of the signal obtained by dividing the earphone terminal signal of {measurement signal} and the time-series encoded data of {terminal detection signal}.

Claim 4 relates to an embodiment of {combination attachment characteristic correction calculation} described in claim 1.

Claim 5 relates to an embodiment of the {earphone correction filter} described in claim 1.

Claim 6 relates to a practical example of a tube used in the {joint attachment} described in claim 1.

Claim 7 relates to a tool necessary for measuring the inherent characteristics of the required earphone when implementing claim 1.

An eighth aspect of the present invention relates to an application program for causing the method for measuring the reproduction characteristics of the earphone described in the first to fourth aspects to function on the OS of the portable terminal.

Claim 9 is an application in which the method for correcting the measured reproduction characteristic unique to the earphone described in claim 1 and claim 5 to {expected earphone reproduction characteristic} is operated on the OS of the portable terminal. Regarding the program.

{Measurement signal} Mainly white noise in acoustic frequency band {Earphone specific characteristic} Earphone reproduction characteristic by a measuring device conforming to a specific industrial standard {Combined attachment} Tube for acoustic coupling of left and right earphones {Playback earphone} Signal} reproducing earphone {detecting earphone} earphone instead of microphone {actual acoustic coupling signal} {detecting earphone} voice coil electromotive force {terminal detection signal} earphone terminal electromotive force {voltage drop signal} earphone Voltage drop at ground common part of lead wire {acoustic coupling signal} {terminal detection signal}-{voltage drop signal}
{Voltage Drop Correction Calculation Procedure} {Terminal Detection Signal}-{Voltage Drop Signal} Calculation Procedure {Coupling Characteristics} For the frequency of {acoustic coupling signal} due to reproduction of white noise
Strength characteristics {Bonding attachment characteristics correction calculation procedure}
Calculation procedure for correcting transfer characteristics of {joint attachment} from {joint characteristic} {right and left earphone joint characteristic} {combination attachment characteristic correction computation procedure} calculation result {left and right earphone joint characteristic correction computation procedure}
The left and right earphones are acoustically coupled from {the left and right earphone coupling characteristics}
To correct the peculiarity of the method of measuring the earphone playback characteristics
Calculation procedure {Earphone regeneration characteristics before correction}
{Right and left earphone coupling characteristic correction calculation procedure} calculation result {earphone correction filter}
{Earphone correction characteristics before correction} Filter to correct the expected reproduction characteristics {Earphone correction filter parameter group}
Parameter group for determining the characteristics of {earphone correction filter} {correction parameter determination function}
{Earphone correction filter parameter group} parameter group
Control function to be determined {Earphone regeneration characteristics after correction}
Of earphones corrected by {Earphone correction filter}
Reproduction characteristics {Expected earphone reproduction characteristics}
The target playback characteristics of the earphones that want to correct the sound quality {EQ simulator} Simulate the characteristics of the actual {earphone correction filter}
The parameter determined by {EQ simulator}
Transfer to the actual {Earphone correction filter}.

01 Measurement example of {measurement signal} earphone terminal
02 Measurement example of {terminal detection signal} when there is a shared ground line
03 Measurement example of {terminal detection signal} when there is no shared ground line
04 Calculation result of correcting voltage drop of shared ground line for 02 signal
05 04 Calculation result of correcting characteristic of {joint attachment} for 04 signal
06 05 Calculation result of square root of intensity on each frequency axis
07 Measured values of test earphones corrected to {expected earphone reproduction characteristics} by {earphone correction filter}
071 Reproduction characteristics calculation results of the test earphones measured in the production process of the test earphones
08 Example of voltage measurement across a pure resistor due to constant current white noise
09 Voltage measurement example of earphone terminal by constant current white noise
1 {Playback earphone}
2 {Detection earphone}
3 {joint attachment}
4 {Measurement signal}
5 Playback sound transmission path
6 Electromotive force of {detection earphone}
7 3-terminal earphone plug
8 Branch point from shared ground line to left and right
9 Shared ground wire part
10 Three-terminal plug ground contact
11 Lead wire of playback side earphone
12 Contact part of playback side earphone with 3 terminal plug
21 {Detection earphone} lead wire
22 Contact part of {Detection side earphone} of 3 terminal plug
31 {Combination attachment}
71 Connection between the earphone plug and the mobile device jack
72 Mobile phone jack
91 Shared ground line
101 Playback earphone piece
111 Ground lead wire for playback earphone
112 Playing earphone hot lead wire
201 Earphone piece on the detection side
211 Ground lead wire of detecting earphone
212 Hot ear lead wire of detecting earphone

GND Ground terminal
L Plug or jack left terminal
R Plug or jack right terminal
MIC Microphone jack
WHITE-NOISE
White noise generator
D <-A Analog-to-digital converter
D-> A Digital-analog converter
Fi (t) {Time measurement encoded data}
Time-series encoded data of Fec (t) {terminal detection signal}
DELAY time difference
s time difference
k Coefficient for calculating the electromotive force corresponding to the voltage drop of the shared ground line of the earphone
{k, s} -CONTROL
Adjustment function of coefficient k and time difference s
DIFF1 subtraction function
FFT fast Fourier transform
COMP-DATA
Parameters that correct the special characteristics of {joint attachment} and {joint characteristics} that are measured by acoustically coupling the left and right earphones
MODIFY
Function to correct FFT output with COMP-DATA correction parameter
SQR Square root function
EARPHONE-CHARA.
Characteristics of the test earphones obtained as a result of correcting the voltage drop and the special characteristics of the measurement method from the {terminal detection signal}
eq1, eq2, eq3, eq4, eq5
Each secondary filter
DIFF2 subtraction function
EQ1, EQ2, EQ3, EQ4, EQ5
{EQ simulator} corresponding to eq1, eq2, eq3, eq4, eq5
REFFERENCE
Frequency characteristics {Expected earphone reproduction characteristics} pattern
EQ-CONTROL
5 filter parameter control function that minimizes DIFF2 subtraction result
The unique playback characteristics of earphones determined by PARAMETER-SET EQ-CONTROL

In the following text, including the following description and claims, the following terms are defined:
The terms defined in the claims are the same in the specification.
In the following description, the symbol {} is used mainly for the description term in order to define the description more accurately so that the scope of interpretation does not vary, and the description in {} is the description outside {}. Shall have priority over.

Reproduction characteristics measurement of earphones Reproduction characteristic correction of earphones {Mobile terminal} with a music reproduction function called a portable personal computer or a smart phone has a powerful calculation processing function, a large amount of memory and an acoustic signal input / output function, or a microphone Input function}, which are sufficient functions for measuring the reproduction characteristics of the earphone.
Acoustic signal processing Smartphone music player signal processing mechanism Least squares fast Fourier transform

First, the sound quality of each type of earphone on the market is significantly different.
Second, many users do not know what the absolute standard sound quality is.
Third, the user can correct the reproduction characteristics of the earphones {subjective, individual auditory characteristics, unique sound quality for each song, and an authorized method that does not depend on the earphone wearing state} There is no.
Fourth, each type of music player has a characteristic sound quality selection function, and it is difficult for many users to intentionally select an expected sound quality.

First, the sound outlets of the pair of left and right earphones are acoustically coupled so that one side functions for reproducing the {measurement signal} and the other functions for detection as a microphone.
{Measurement signal} is reproduced from the {portable terminal}, input to the terminal of one earphone, and the electromotive force generated at the terminal of the other earphone is captured.
Second, the voltage drop of the lead wire shared by the left and right earphones is corrected, and the {coupling characteristics} of {detection-side earphones} are calculated purely due to acoustic coupling.
Thirdly, the correction of the specificity of {acoustic attachment} in {coupling characteristics} and the method of using left and right earphones for reproduction and detection are added.
Based on the above results, the reproduction characteristics specific to each earphone are calculated.
Fourth, a parameter group of a filter that approximates the inherent reproduction characteristic of the measured earphone to {expected earphone reproduction characteristic} is obtained.
Fifth, by embedding the obtained parameter group in the filter for actual operation, a filter that corrects the peculiarity of a specific earphone to {expected earphone reproduction characteristics} is configured.
Sixth, player playback data is input to the filter group, and a playback signal having a sound quality approximate to {expected earphone playback characteristics} is obtained from the output of the filter group.
Seventh, the playback function, microphone function, calculation function, and display function of the portable terminal are used.

First, the reproduction sound quality can be corrected so that {the sound quality of the earphones owned by each user} can be reproduced with a certain level of sound quality by each user's own hands.
Second, the sound quality of the earphones corrected so as to achieve the sound quality of {expected earphone reproduction characteristics} facilitates selection of the sound quality preferred by each user based on a certain level of sound quality.

These are explanatory drawings of one Example of the acoustic coupling of an earphone on either side. These are explanatory drawings of one Example of the acoustic coupling of an earphone on either side. These are explanatory drawings of one Example of the acoustic coupling of an earphone on either side. FIG. 4 is an explanatory diagram when the left and right earphone lead wires share a part of the ground line. These are explanatory drawings of the example of a connection of an earphone which is possible when the portable terminal device has left and right earphone outputs and one microphone input terminal. These are explanatory drawing of the example of a connection of an earphone possible when a portable terminal device has a right and left sound output and a right and left microphone input terminal. These are explanatory drawing of an example of {structure and process} which measures and calculates the reproduction characteristic of an earphone. These are explanatory drawing of an example of {structure and process} which measures and calculates the reproduction characteristic of an earphone. Is based on the measurement result of the reproduction characteristics of the earphone, {an example of how to determine the parameter of the filter} for correcting to the target characteristic, and {the filter having the determined parameter, Explanatory drawing of {structure and process} of an example of a method for correcting the characteristics. Shows an example of acoustic coupling measurement and correction of voltage drop for an earphone with a strong habit of reproduction characteristics. These are characteristic examples for each process from calculating the earphone coupling characteristics to calculating the earphone reproduction characteristics. Is a reproduction characteristic obtained by converting the obtained earphone characteristic into {expected earphone reproduction characteristic}. Is the inspection data of the earphone production process used in the measurement example. Is a comparison of {pure resistance} and {impedance characteristics of earphones including lead wires}

{Application program of portable terminal device for measuring earphone characteristics}, {Coupling attachment}, and {Connection adapter for measurement}.

Supply {Application Program}, {Combination Attachment} and {Measurement Connection Adapter} to the consumer market as products.

FIG. 1 is an explanatory diagram of an embodiment of acoustic coupling of left and right earphones.
The state where the left and right earphones are acoustically coupled with the earpiece of a general earphone removed is shown.
1 is {playback earphone}, 2 is {detection earphone}, 3 is {joint attachment},
4 is a {measurement signal}, 5 is a path through which the reproduction sound of the {playback earphone} is transmitted to the {detection earphone}, and 6 is an electromotive force of the detection earphone.

{Combination Attachment} has a role of acoustically coupling the left and right earphones.
The reproduced sound from the {reproducing earphone} is transmitted to the diaphragm of the {detecting earphone} via the sound outlets of both earphones. The vibration of the diaphragm generates an electromotive force. The relationship of the electromotive force to the {measurement signal} depends on the conversion characteristics of the earphone. Although it is a rough tendency, the electromotive force obtained by acoustically coupling the left and right of the earphone, that is, {actual acoustic coupling signal}, is proportional to the square of the reproduction characteristic of the earphone. Therefore, by adding a correction that {obtained {relation of {acoustic coupling signal} to {measurement signal}}, that is, a square root of intensity for each frequency of {coupling characteristic}, reproduction characteristics of an actual earphone are added. A measurement result close to can be obtained.

A specific calculation formula for correction has a characteristic unique to each measurement system, and it is the essence of the present invention to apply correction to the specific characteristic. Since the detailed definition of each unique property is not the essence of the present invention, a description thereof will be omitted.

There are the following two largest factors to be corrected with respect to {acoustic coupling detection signal}.
First, since the same earphone is used synergistically on the playback side and the detection side in the measurement system,
The square of the characteristic of the earphone is reflected in the measurement result.
Second, the size and shape of the coupling attachment.

FIG. 2 is an explanatory diagram of an embodiment of acoustic coupling of left and right earphones.
A state in which the left and right earphones are acoustically coupled in a state where the earpieces of general earphones are attached is shown.
The same number as FIG. 1 is the same function. 101 and 201 are left and right earpieces, respectively, and 31 is a joint attachment.
The factor to be corrected for {terminal detection signal} is the same as in FIG.

FIG. 3 is an explanatory diagram of an embodiment of acoustic coupling of the left and right earphones.
A state in which the left and right earphones are acoustically coupled in a state where the earpieces of general earphones are attached is shown.
3, the same number as FIG. 1 and the same number as FIG. 2 have the same functions. 32 is {{sound absorbing piece}} inserted in the tube of {{connection attachment}}. Inside the {joint attachment}, acoustic energy is transmitted from one to the other, but the reflection of sound waves occurs depending on the material and shape dimensions. The reflection of the sound wave affects the measurement result {coupling characteristic}, and causes an error. Even in the actual use state where the earphone is worn on the ear, there is some reflection of sound waves in the transmission path, and the details of the characteristics are complicated. It is also affected by the type of earphone and the insertion state of the earphone. It is not easy to finely correct the influence of such reflected waves, and it is not a factor that greatly affects the overall sound quality. However, it is desirable that reflection is suppressed in the sense of reducing measurement errors. As shown in FIG. 3, providing an appropriate sound absorbing material inside the coupling tube is a simple and effective means.
The above corresponds to claim 6.

FIG. 4 is an explanatory diagram when a part of the ground line of the left and right earphones is shared.
The same number as FIG. 1 is the same function.
11 and 21 are branched left and right earphone leads, 7 is the body part of the earphone plug, 10 is the ground terminal of the earphone plug, 12 and 22 are the hot sides of the left and right earphone terminals, and 8 is the left and right earphones, respectively. The branch point of the common part of the ground lead wire, 9 is the part sharing the ground line of the left and right earphones. Most earphone plugs on the market have three terminals with a common ground. The length of the portion sharing the left and right ground lines also varies depending on the type of earphone. Some types do not have a shared portion of the ground line. In general, since the left and right ground lines are shared in the wiring inside the earphone plug and the portable terminal, strictly speaking, it is considered that there is a shared part of the ground lines of all the earphones.

In the shared portion of the ground line, a voltage drop due to the current flowing through the {playback earphone} occurs. The voltage drop in the shared part of the ground line is added to the electromotive force due to the pure acoustic coupling of the detecting earphone. Since the electromotive force of the detection-side earphone is small, the voltage drop at the shared portion of the ground line greatly affects the measurement error, so it needs to be precisely removed.

FIG. 5 is an explanatory diagram of the connection between the earphone jack and the earphone plug when the portable terminal has left and right sound outputs and one microphone input terminal.
1 and 4 are the same functions. GND is ground, L is left side, R is right side, MIC is microphone input, 7 is earphone plug, 71 is relay connection for measurement between earphone plug and earphone jack, 72 is earphone jack, 91 is sharing the left and right ground lines Parts 10, 10, and 22 are the earphone plug ground terminal, left terminal, and right terminal, 111 and 211 are the parts where the ground wires are branched and connected to the ground terminals of the left and right earphones, and 112 and 212 are each It is a lead wire on the hot side of the left and right earphones.
71 relays the connection of the earphone jack of the portable terminal from the earphone plug. It has a role for connection conversion that converts the connection of the terminal to measure the characteristics of the earphone.

The GND of the portable terminal is connected to the shared GND terminal of the earphone.
The L side of the mobile terminal is connected to the L side hot terminal of the earphone, and supplies {measuring signal} to the {playback side earphone}.
The wiring is changed so that the MIC input of the portable terminal is connected to the R side hot terminal of the earphone, and the electromotive force of the {detection earphone} becomes the MIC input.
In the shared ground line portion 91, a voltage drop occurs due to the current flowing through the {playback earphone}, and is added to the electromotive force generated by the right earphone due to the voltage drop, and measured at the right earphone terminal {terminal detection signal} Become.

FIG. 6 is an explanatory diagram of connection of earphones when the portable terminal has left and right sound outputs and left and right microphone input terminals.
The same reference numerals as those in FIG. 5 in FIG. 6 denote the same functions. The internal wiring of the connection conversion plug jack 71 is different from that shown in FIG. Reference numerals 711 and 712 denote resistors for dividing the measurement signal. The divided {measurement signal} is connected to the L side of the sound input terminal of the portable terminal. The R side is connected to the {detection side earphone} as in FIG. By this method, the voltage proportional to {measurement signal} and {terminal detection signal} generated by {measurement signal} are not affected by the time delay of the digital signal processing system and the degradation of the characteristics of the analog system, Both will be measured under the same conditions. However, depending on the device, the function of converting to the left and right digital codes may have a time difference corresponding to a half cycle of sampling. Therefore, as described in claim 3, Hxmin (t) must be verified by trying a time difference of a half cycle of sampling.

FIG. 7 is an explanatory diagram of the structure and process for measuring and calculating the reproduction characteristics of the earphone.
The present invention is applied to a portable terminal having a monaural microphone input terminal as shown in FIG.
The mobile phone which is used to correct the {voltage drop of the ground line of the earphone described in claim 2} and {transfer characteristic of the coupling attachment} and {speciality by using the left and right earphones on the reproduction side and the detection side}. A block diagram of the structure and process of an application program that functions on the OS of the terminal is shown.
In the portable terminal, the time series code data to be reproduced is transferred to the output function in the acoustic signal reproduction process, and an indefinite delay of about 100 msec to 3 sec occurs. It is necessary to calculate Hxmin (t) by trying the time difference.
In Fig. 7, since Fi (t) is time-series encoded data, there is an uncertain time difference from 100msec to 3sec with Fec (t). Buffer memory is required.
If the time difference between the two recorded signals to be compared for the calculation of the {combining characteristics} is long, it takes a few seconds, and it is influenced by the size of the data buffer memory that depends on the operating status of the mobile terminal, the model, and the playback music. Since the delay time is greatly influenced, it takes time to specify the time difference s according to claim 3. However, since the measurement time is faster than human movement, there is no problem in practical use.

The same reference numerals as those in FIG. 5 in FIG.
Fi (t) is time-series encoded data in which white noise that is {measurement signal} is recorded,
Fec (t) is time-series encoded data in which {terminal detection signal} is recorded,
DELAY is a read relative address corresponding to the time of the time-series encoded data corresponding to the time difference s according to claim 2. The time difference of half the sampling period, which is the smallest unit of s, is obtained from the previous and subsequent data.
k is the proportionality factor,
{k, s} CONTROL is a function that determines kmin and smin that satisfy Hxmin (t) described in claim 2 by operating k and s, s is in the range of 0.1 to 3 seconds,
DIFF1 is a function for generating the difference signal Fec (t) −k * Fi (ts) described in claim 2;
FFT is a fast Fourier transform function for finding {coupling characteristics}
COMP-DATA is a correction characteristic of {specificity of {joint attachment} and {speciality of transfer characteristic of using left and right earphones for reproduction and detection}, as described in claim 4;
MODIFY receives COMP-DATA and corrects the intensity for each frequency in {coupling characteristics}
SQR is a function for obtaining the square root of the intensities corresponding to the respective frequency characteristics output from MODFY, FFT, COMP-DATA, MODIFY, SQR corresponds to {binding attachment correction characteristic calculation process} description in claim 4 .
EARPHONE-CHARA is {earphone characteristics before correction}.
D-> A is the digital-analog converter
D <-A is the analog-digital converter

FIG. 8 is an explanatory diagram of the structure and process for measuring and calculating the reproduction characteristics of the earphone.
The present invention can be applied to a portable terminal having a stereo microphone input terminal as shown in FIG.
The correction of {the voltage drop of the ground line of the earphone described in claim 3}, {the transfer characteristic of the {connection attachment}} and {the speciality by using the left and right earphones on the reproduction side and the detection side} is applied. A block diagram of the structure and process of an application program functioning on the OS of the mobile terminal is shown.
{Coupling characteristics} Since the time difference between two recording signals to be compared for calculation is at most half the sampling period, the calculation time of the voltage drop at the common part of the ground line of the earphone is short.
Since the conditions for generating the two data to be compared are aligned, the influence of the error of the analog system inside the terminal is extremely small compared to FIG.

The same numbers in FIG. 8 as those in FIGS. 6 and 7 have the same functions.
WHITE-NOISE is {noise signal} white noise data,
Fi (t) is time-series encoded data that records a signal obtained by dividing the voltage of the earphone terminal of {playback earphone},
Fec (t) is time-series encoded data in which {terminal detection signal} is recorded,
DELAY is a read relative address of time-series encoded data corresponding to the time difference s according to claim 3. The time difference of half the sampling period is obtained from the previous and next data.

FIG. 9 is an explanatory diagram of the structure and process of an embodiment for correcting the reproduction characteristics of the earphones measured and calculated to the desired reproduction characteristics.
FIG. 9 shows an example of a correction method using a filter corresponding to claim 4, but the type and specific configuration of {correction filter} are not the essence of the present invention.

FIG. 9A is a block for reproducing sound as a player. An example of the structure and process of a function in which five secondary filters correct the earphone-specific reproduction characteristics to {expected earphone reproduction characteristics}. Indicates.
MUSIC-DATA is the music data to play,
Each of eq1, eq2, eq3, eq4, and eq5 is a secondary filter, and the parameters that determine the characteristics of each filter are determined by the block shown in FIG. 9B.
PARAMETER-SET is a parameter group that determines the characteristics of each filter.
Each of eq1, eq2, eq3, eq4, and eq5 is responsible for the variation range of the characteristics of {super bass, mid bass, mid treble, treble, super treble}. The variation range is an example, and the variation range is not the essence of the present invention.
The output of eq5 is time-series encoded data obtained by correcting the peculiarity of the reproduction characteristic inherent to the earphone to the intended reproduction characteristic.
OUTPUT is a function to reproduce time-series encoded data in real time,
EARPHONE is an earphone,
SOUND is the playback sound.

In the description of FIG. 9, the number of filters is five. However, in general, the characteristics specific to the earphone are affected by the environment in which they are used, and are quite complicated at a fine level. Correction of these fine characteristics is not an important factor for normal listening. The difference in sound quality can be evaluated by dividing it into the above five bands, or at most seven bands. The number of filters is not the essence of the present invention. The number of earphones is generally an arbitrary plural number, but practically, at least three and at most seven function sufficiently in practical use.
The sound quality of the playback sound SOUND is the sound quality corrected so that the special characteristics of the earphones are brought closer to the {expected earphone playback characteristics} by eq1, eq2, eq3, eq4, eq5.
There is a problem as to whether the sound quality corrected to {expected earphone reproduction characteristics} matches the user's preference. It is not the essence of the invention of the present invention that the output of eq5 is an earphone output or that the user can select a desired sound quality to the output of eq5.

FIG. 9B is an explanatory diagram of the structure and process of the function for determining the parameter group of the filter group from eq1 to eq5 in FIG. 9A and obtaining the correction characteristic of the earphone.
EARPHONE-CHAR. Is an intensity characteristic with respect to the frequency of a specific earphone obtained by the function shown in the embodiment of FIG. This characteristic is a two-dimensional pattern of intensity with respect to frequency, which is input to EQ1.
Let {EQ simulator} be a function for correcting a filter with a pattern of intensity characteristics with respect to frequency instead of signal processing.
EQ1, EQ2, EQ3, EQ4, and EQ5 are {EQ simulators} each having a limitation on the variable range of parameters for correcting the special characteristics of {joint attachment}.
Five {EQ simulator} corresponds to the five filter of FIG. 9 (a), the variable range of the respective {EQ simulator} is the same as the variation range of each filter of FIG. 9 (a).
The output of EQ5 is obtained by correcting EARPHONE-CHAR. By connecting 5 EQ simulators in series.
REFFERENCE is the {expected earphone reproduction characteristic} described in claim 1.
The definition of the characteristic of {expected earphone reproduction characteristic} is not the essence of the present invention.
DIFF2 is a comparison function between {EQ5 output and REFFERENCE}. The comparison result is the degree of difference in the intensity for each frequency in all frequency bands.
EQ-CONTROL adjusts and determines the parameter group of five {EQ simulator} to minimize the degree of difference between {EQ5 output and REFFERENCE}. The parameter group can be expressed by three parameters: center frequency, Q value, and gain of each {EQ simulator}.
The parameter group determined by EQ control is transferred to PARAMETAER-SET as the parameters of equalizers eq1 to eq5 that control the actual signal processing in Fig. 9 (a).

Although it is theoretically possible to obtain an accurate correction characteristic by multiplying {expected earphone reproduction characteristic} by {reciprocal of measured reproduction characteristic of earphone}, in general, as a filter for actual operation, Since the scale is large and there are instability factors in the calculation process and there is no solution, it is necessary to deal with the judgment function and is not practical. The method of FIG. 9 is a simple and practical method.

FIG. 10 is a measurement example of acoustic coupling of an earphone having a wrinkle strong in reproduction characteristics.
This is a characteristic of an actual measurement value as a result of actual operation of {Voltage drop correction calculation step} of claim 3.
The horizontal axis represents frequency, and the vertical axis represents signal or coupling strength at each frequency. The intensity of the vertical axis of each graph is not clearly defined as 0 dB, but is an expression value that does not correct the absolute scale in each process of measurement results and calculation results, and evaluates the relative relationship between characteristics It is a characteristic to do.

01 is {measurement signal},
02 is an actual measurement example of the {terminal detection signal} of the test earphone by acoustic coupling when there is a voltage drop of the shared ground line,
03 is an example of actual measurement of {terminal detection signal} of the test earphone when there is no shared ground line,
04 is an actual measurement example of the {coupling characteristic} of the test earphone by acoustic coupling when automatic correction of the voltage drop of the shared ground line is applied by the method described in claim 3. However, since the resolution of the time difference is used as the sampling period, an error corresponding to a half period is included.
05 is a frequency characteristic with the transfer characteristic of {joint attachment} corrected for 04,

The slight difference between 03 and 04 below 8kHz arises from the measurement error and can be ignored in the light of correction of the characteristic of the earphone, which is the essence of the present invention.
The difference of around 10dB between 8 and 03 between 03 and 04 is generated from the measurement system. This is due to the measurement by a consumer use notebook PC not designed as a measuring instrument, and is mainly an error due to {a phase difference of half the sampling period that occurs when the left and right signals are digitally converted}.
In this frequency band, the difference between the standard measuring instrument and the actual use state is large, and the variation in characteristics depending on the wearing state of the earphone is very large, so that the correction based on the measurement result is less important.
For the above reasons, it can be determined that the measurement result of {coupling characteristics} by the method of claim 3 is practically sufficient.

FIG. 11 shows the characteristics for each process from the measurement result of the coupling characteristics of the left and right earphones to the calculation of the reproduction characteristics of the earphones.
It is an actual measurement value as a result of actually operating the {square root calculation step} described in claim 4.
04, the voltage drop of the shares of the ground lines from the detection side {terminal detection signal} a frequency characteristic of the automatic correction signal is the same as 04 in FIG. 10.
05 is the frequency characteristic of the signal corrected for the transfer characteristic of {joint attachment} relative to 04,
06 is the square root of the intensity on each frequency axis of 05.
The frequency characteristics of the signal obtained by {determining the square root of the intensity on each frequency} of the measured value of {coupling characteristics} are approximated to the characteristics of the factory ear inspection of the earphones to be tested. The measurement result of the earphone characteristic calculated by one example of {Earphone reproduction characteristic calculation process} of correcting the output characteristic} is shown.

FIG. 12 shows reproduction characteristics obtained by converting the characteristics of the obtained earphones into {expected earphone reproduction characteristics}.
Reference numeral 07 denotes reproduction characteristics of the test earphone using white noise as an input and the output of the {correction filter} in which the {correction parameter group} of the test earphone is embedded as a reproduction signal.
FIG. 6 is a connection diagram showing measurement and calculation according to the embodiment shown in the block diagram of FIG. 8, and calculation and correction of the reproduction characteristics of the test earphone with the five secondary filters shown in the block diagram of FIG. Reproduction characteristics.
{The device that measured the characteristics of Fig. 12 and the device that measured the characteristics of Fig. 13 are of different types}, {Accuracy due to the five correction filters} and {the measurement system's peculiarity This indicates that the strong characteristic of the original wrinkle has been greatly corrected as indicated by the characteristic 071 in FIG. 13 or 06 in FIG.

Fig. 13 shows the test results of the earphone production process used in the measurement example.
071 is the frequency characteristic.
Generally, since it is measured according to a standardized industrial standard, it may be considered that it represents an intrinsic characteristic of the earphone.
The inspection results in the production process do not necessarily represent the absolute characteristics of the earphones, and the characteristics of 071 should be read as insufficient accuracy in the acoustic coupling system of the measuring instrument in the range of 5000 Hz or higher. Can do.
{Earphones reproduction characteristic calculation process} results, i.e. so that the frequency characteristic 04 of FIG. 9 approaches the frequency characteristic 071 of FIG. 11, to design the calculated stroke of {earphones reproduction characteristic calculation step} is a practical approach .

FIG. 14 is an actual measurement example of frequency characteristics comparing the electric impedance of the earphone and the impedance of the pure resistance. 08 is the frequency characteristic of the voltage across the pure resistor due to constant current white noise, and 09 is the frequency characteristic of the voltage at the earphone terminal due to constant current white noise. Both are flat in the acoustic frequency band, and the electrical impedance of the earphone can be calculated as a pure resistance.
Therefore, it is data that supports the fact that the error calculation which is a practical problem is not generated in the method of actual measurement calculation by regarding the lead wire of the earphone and the voice coil of the earphone of claim 2 and claim 3 as a pure resistance.
11, 12, and 14 show the measurement results when the measurement signal is white noise, but the case where the measurement signal is based on a sine wave sweep also has a one-to-one correspondence with the case where the measurement signal is based on white noise.

Claim 1 relates to a basic method of the present invention, and is based on a combination of the following methods.
Use {joint attachment}.
The left and right earphones are joined with {joint attachment}.
Sound signal is detected by playing {measurement signal} from one side and microphone as the other side.
Corrects the voltage drop at the part of the earphone lead wire sharing the ground wire.
Correct the transfer characteristics of {joint attachment}.
Correction of transfer characteristics where left and right earphones are used for playback and detection.
Correction of measured earphone characteristics to {expected earphone reproduction characteristics}

Claim 2 is an embodiment of the {voltage drop correction calculation process} described in claim 1 and relates to a specific method that can be applied when the microphone input of the portable terminal is monaural. Depending on the combination.
Play {measurement signal} from {playback earphone}.
Measure {terminal detection signal} of {detection side earphone} with monaural microphone input.
{Coupling characteristic} is calculated from time-series code data of {measurement signal} and {terminal detection signal} time-series encoded data

Claim 3 is an embodiment of the {voltage drop correction calculation process} described in claim 1 and relates to a specific method that can be applied when the microphone input of the portable terminal is stereo. Depending on the combination.
Play {measurement signal} from {playback earphone}.
Measure {terminal detection signal} of {detection side earphone} on the R side of stereo microphone input.
Measure the divided signal of {measurement signal} on the L side of the stereo microphone input.
The {coupling characteristic} is calculated from the time-series encoded data of the signal obtained by dividing the earphone terminal signal of {measurement signal} and the time-series encoded data of {terminal detection signal}.

Claim 4 relates to an embodiment of {combination attachment characteristic correction calculation} described in claim 1.

Claim 5 relates to an embodiment of the {earphone correction filter} described in claim 1.

Claim 6 relates to a practical example of a tube used in the {joint attachment} described in claim 1.

Claim 7 relates to a tool necessary for measuring the inherent characteristics of the required earphone when implementing claim 1.

An eighth aspect of the present invention relates to an application program for causing the method for measuring the reproduction characteristics of the earphone described in the first to fourth aspects to function on the OS of the portable terminal.

Claim 9 is an application in which the method for correcting the measured reproduction characteristic unique to the earphone described in claim 1 and claim 5 to {expected earphone reproduction characteristic} is operated on the OS of the portable terminal. Regarding the program.

{Measurement signal} Mainly white noise in acoustic frequency band {Earphone specific characteristic} Earphone reproduction characteristic by a measuring device conforming to a specific industrial standard {Combined attachment} Tube for acoustic coupling of left and right earphones {Playback earphone} Signal} reproducing earphone {detecting earphone} earphone instead of microphone {actual acoustic coupling signal} {detecting earphone} voice coil electromotive force {terminal detection signal} earphone terminal electromotive force {voltage drop signal} earphone Voltage drop at ground common part of lead wire {acoustic coupling signal} {terminal detection signal}-{voltage drop signal}
{Voltage drop correction calculation process} {Terminal detection signal}-{Voltage drop signal} calculation procedure {Coupling characteristic}
Strength characteristics {Bonding attachment characteristics correction calculation process}
Calculation procedure {correction process for correcting left and right earphone connection characteristics} calculation process {correction process for correcting right and left earphone connection characteristics }
The left and right earphones are acoustically coupled from {the left and right earphone coupling characteristics}
To correct the peculiarity of the method of measuring the earphone playback characteristics
Calculation procedure {Earphone regeneration characteristics before correction}
{Right and left earphone coupling characteristic correction calculation process} calculation result {earphone correction filter}
{Earphone correction characteristics before correction} Filter to correct the expected reproduction characteristics {Earphone correction filter parameter group}
Parameter group for determining the characteristics of {earphone correction filter} {correction parameter determination function}
{Earphone correction filter parameter group} parameter group
Control function to be determined {Earphone regeneration characteristics after correction}
Of earphones corrected by {Earphone correction filter}
Reproduction characteristics {Expected earphone reproduction characteristics}
The target playback characteristics of the earphones that want to correct the sound quality {EQ simulator} Simulate the characteristics of the actual {earphone correction filter}
The parameter determined by {EQ simulator}
Transfer to the actual {Earphone correction filter}.

01 Measurement example of {measurement signal} earphone terminal
02 Measurement example of {terminal detection signal} when there is a shared ground line
03 Measurement example of {terminal detection signal} when there is no shared ground line
04 Calculation result of correcting voltage drop of shared ground line for 02 signal
05 04 Calculation result of correcting characteristic of {joint attachment} for 04 signal
06 05 Calculation result of square root of intensity on each frequency axis
07 Measured values of test earphones corrected to {expected earphone reproduction characteristics} by {earphone correction filter}
071 Reproduction characteristics calculation results of the test earphones measured in the production process of the test earphones
08 Example of voltage measurement across a pure resistor due to constant current white noise
09 Voltage measurement example of earphone terminal by constant current white noise
1 {Playback earphone}
2 {Detection earphone}
3 {joint attachment}
4 {Measurement signal}
5 Playback sound transmission path
6 Electromotive force of {detection earphone}
7 3-terminal earphone plug
8 Branch point from shared ground line to left and right
9 Shared ground wire part
10 Three-terminal plug ground contact
11 Lead wire of playback side earphone
12 Contact part of playback side earphone with 3 terminal plug
21 {Detection earphone} lead wire
22 Contact part of {Detection side earphone} of 3 terminal plug
31 {Combination attachment}
71 Connection between the earphone plug and the mobile device jack
72 Mobile phone jack
91 Shared ground line
101 Playback earphone piece
111 Ground lead wire for playback earphone
112 Playing earphone hot lead wire
201 Earphone piece on the detection side
211 Ground lead wire of detecting earphone
212 Hot ear lead wire of detecting earphone

GND Ground terminal
L Plug or jack left terminal
R Plug or jack right terminal
MIC Microphone jack
WHITE-NOISE
White noise generator
D <-A Analog-to-digital converter
D-> A Digital-analog converter
Fi (t) {Time measurement encoded data}
Time-series encoded data of Fec (t) {terminal detection signal}
DELAY time difference
s time difference
k Coefficient for calculating the electromotive force corresponding to the voltage drop of the shared ground line of the earphone
{k, s} -CONTROL
Adjustment function of coefficient k and time difference s
DIFF1 subtraction function
FFT fast Fourier transform
COMP-DATA
Parameters that correct the special characteristics of {joint attachment} and {joint characteristics} that are measured by acoustically coupling the left and right earphones
MODIFY
Function to correct FFT output with COMP-DATA correction parameter
SQR Square root function
EARPHONE-CHARA.
Characteristics of the test earphones obtained as a result of correcting the voltage drop and the special characteristics of the measurement method from the {terminal detection signal}
eq1, eq2, eq3, eq4, eq5
Each secondary filter
DIFF2 subtraction function
EQ1, EQ2, EQ3, EQ4, EQ5
{EQ simulator} corresponding to eq1, eq2, eq3, eq4, eq5
REFFERENCE
Frequency characteristics {Expected earphone reproduction characteristics} pattern
EQ-CONTROL
5 filter parameter control function that minimizes DIFF2 subtraction result
The unique playback characteristics of earphones determined by PARAMETER-SET EQ-CONTROL

Claims (9)

In the following description, the symbol {} is used mainly for the description term in order to define the description more accurately so that the scope of interpretation does not vary, and the description in {} is the description outside {}. Shall have priority over
{Measurement signal} is an acoustic frequency band white noise or sine wave sweep signal,
Intensity is the magnitude of a signal or characteristic or gain that corresponds to an rms or average or maximum value,
{Earphone specific characteristic} is the frequency characteristic of the acoustic output with respect to the electrical input, measured by a measuring device in which the characteristic of the earphone conforms to a specific industrial standard,
The symbols +-* are the operators for addition, subtraction, multiplication of the left and right terms,
The range of sound reproduction with respect to characteristics, signals and functions shall be an effective range for practical sound signals,
An electronic device with a sound input / output function, such as a computer, a mobile phone, or a smartphone, is called a “portable terminal”.
The function that acoustically couples the sound outlets of the left and right earphones is {joint attachment},
The {joint attachment} has a structure in which both ends of the tubular pipe are connected to the sound outlet of the earphone, and the distance between both ends of the sound outlet of the left and right earphones is 5 cm or less.
The first feature is the use of {joint attachment}
It is assumed that the signal for measuring the characteristics of the earphone is {measurement signal}
In addition to obtaining a sound output by adding {measuring signal} to either one of the left and right earphone terminals, the electromotive force generated in the other one of the earphones by the acoustic coupling via the {coupling attachment} Detecting from the terminal is the second feature,
The earphone on the playback side of {measurement signal} is {playback earphone},
The earphone on the detection side of the electromotive force is {detection side earphone}
The electromotive force generated in the voice coil of the {detection side earphone} is {actual acoustic coupling signal},
The electromotive force detected at the earphone terminal of the {detection side earphone} is {terminal detection signal},
{Voltage drop signal} is a voltage drop in the shared part of the ground line of the left and right earphones included in {terminal detection signal},
The signal obtained by subtracting {voltage drop signal} from {terminal detection signal} is {acoustic coupling signal}, and {actual acoustic coupling signal} and {acoustic coupling signal} match within an error range that can be practically used. Use the fact that
The calculation process for deriving {acoustic coupling signal} from {terminal detection signal} is {voltage drop correction calculation procedure},
It has a third feature of having {voltage drop correction calculation procedure}
{Generally, the inverse of Fourier-transformed {measurement signal} is multiplied by Fourier-transformed {acoustic coupling signal}} or {practically {transformed with {measurement signal} as a reference { Acoustic coupling signal} property} to {coupling property}
{Coupling characteristic} is expressed as an intensity characteristic with respect to frequency.
By correcting the inherent transfer characteristic of {bond attachment} from {bond characteristic} obtained by using a specific {bond attachment}, the calculation process for calculating the bond characteristic of the earphone is performed by calculating {bond attachment characteristic correction calculation}. Procedure}
It has a fourth feature that it has {joint attachment characteristic correction calculation procedure}
The intensity characteristic with respect to the frequency of the signal obtained through the {bonding attachment characteristic correction calculation procedure} is {right and left earphone coupling characteristic},
{Right and left earphone coupling characteristics} is expressed as a pattern of intensity with respect to frequency.
{Calculation process for correcting the speciality of acoustic coupling of the left and right earphones with {joint attachment} with respect to {left and right earphone coupling characteristics}} is {left and right earphone coupling characteristic correction calculation procedure}, Having a procedure} is a fifth feature,
The characteristic of the intensity with respect to the frequency of the reproduction characteristic peculiar to the earphone obtained through the {right and left earphone coupling characteristic correction calculation procedure} is {earphone correction characteristic before correction},
Expected earphone playback characteristics to be {expected earphone playback characteristics}
A filter group consisting of a plurality of filters functioning to approximate {pre-correction earphone reproduction characteristics} of a specific earphone to {expected earphone reproduction characteristics} is referred to as {earphone correction filter},
A plurality of variable parameters that determine the overall characteristics of the {earphone correction filter} are defined as {earphone correction filter parameter group},
The characteristic obtained by multiplying the intensity for each frequency of the characteristics of both the {earphone correction characteristics before correction} and the {earphone correction filter parameter group} determined by {{earphone correction filter parameter group}} is set as {earphone correction characteristics after correction},
The function for determining {earphone correction filter parameter group} of {earphone correction filter} where {{earphone correction characteristics before correction} is converted to {earphone correction characteristics after correction} is {correction parameter determination function}
It has a sixth feature of having {earphone correction filter} and {correction parameter determination function}
For a specific earphone, the {earphone correction filter parameter} functioning with the {earphone correction filter parameter group} determined by the {correction parameter determination function} is incorporated into the signal processing process of the reproduction data of the music to function. And features
Having the first, second, third, fourth, third, fourth, fifth, sixth and seventh features,
The influence of the voltage drop in the common part of the ground line of the left and right earphones,
The specific {joint attachment} corrects the effect of the transfer characteristics due to the acoustic coupling of the left and right earphones, and corrects the obtained earphone characteristics by approximating them to the {expected playback characteristics}. of,
An earphone characteristic correction method for correcting a reproduction characteristic of an earphone so as to approach an expected reproduction characteristic based on a measurement result of a specific reproduction characteristic of the specific earphone. Regarding {voltage drop correction calculation procedure} defined in claim 1,
Let Fi (t) be the time-series encoded data of {measurement signal} where t is time.
The playback signal of Fi (t) is Ei (t),
Playing Ei (t) with {playback earphone} is the eighth feature,
With variable time difference s
Let Fi (t−s) be the time-series encoded data obtained by applying the delay time s to Fi (t).
The minimum resolution of s is half the sampling period of digital encoding,
The means to set the minimum resolution of s to half the sampling period is calculated from data before and after time s.
The value of s is the amount of data sufficient to ensure that the {delay time until the time-series encoded data of the portable terminal is output to the earphone terminal} and the output of {{voltage drop correction calculation procedure}} have a certain level of accuracy. Corresponding time}, and
Ec (t) is the {terminal detection signal} of the {detection earphone}
The digitally encoded Eec (t) is recorded for a specific time and the recorded data is Fec (t).
Let k be an arbitrary proportionality factor,
Let Fec (t) −k * Fi (t−s) be Hx (t),
Let the intensity of Hx (t) be Hx,
The values of k and s that minimize Hx are kmin and smin, respectively.
Let Fex (t) −kmin * Fi (t−smin) be Hxmin (t),
With kmin * Fi (t−smin), it is assumed that the signal component corresponds to the voltage drop in the common part of the left and right lead wires.
The ninth feature is that it has means for obtaining Hxmin (t) by changing the value of k and the value of s.
The tenth characteristic is that the intensity characteristic with respect to the frequency of Hxmin (t) is defined as the {coupling characteristic} defined in claim 1;
Means satisfying the third feature defined in claim 1, that is, means for correcting a measurement error caused by a voltage drop in the common part of the ground line of the left and right earphones has the eighth, ninth and tenth features. However,
An earphone characteristic correction method for correcting a reproduction characteristic of an earphone so as to approach an expected reproduction characteristic based on a measurement result of a specific reproduction characteristic of the specific earphone. Regarding {voltage drop correction calculation procedure} defined in claim 1,
Let Fi (t) be the time-series encoded data of {measurement signal} where t is time.
The playback signal of Fi (t) is Ei (t),
The eleventh feature is that Ei (t) is played with the {playback earphone} defined in claim 1;
In order to adapt Ei (t) to the level of the microphone input, Eo (t) is the signal divided by a specific ratio,
Let Eo (t) time-series encoded data be Fi (t),
The twelfth feature is that it has means for obtaining Fi (t),
Let u be the sampling half-cycle for digital encoding from Eo (t) to Fi (t).
Ec (t) is the {terminal detection signal} of the {detection earphone}
{Voltage drop correction calculation procedure} corresponds to the amount of data sufficient to ensure a certain level of accuracy.
The digitally encoded Eec (t) is recorded for a specific time and the recorded data is Fec (t).
Let s be either + u or a value of 0 or -u,
The means to set the minimum resolution of s to half the sampling period is calculated from data before and after time s.
Let k be an arbitrary proportionality factor,
Let Fec (t) −k * Fi (t−s) be Hx (t),
Let the intensity of Hx (t) be Hx,
The values of k and s that minimize Hx are kmin smin, respectively.
Let Fex (t) −kmin * Fi (t−smin) be Hxmin (t),
Suppose that kmin * Fi (t−smin) has a component corresponding to the voltage drop in the shared part of the left and right lead wires,
The thirteenth feature is that it has means for obtaining Hxmin (t) by changing the value of k and the value of s.
According to the fourteenth feature, the intensity characteristic with respect to the frequency of Hxmin (t) is defined as {coupling characteristic} defined in claim 1.
Means satisfying the third feature defined in claim 1, that is, means for correcting a measurement error caused by a voltage drop in the common part of the ground line of the left and right earphones are the eleventh, twelfth, thirteenth and fourteenth features. Where
An earphone characteristic correction method for correcting a reproduction characteristic of an earphone so as to approach an expected reproduction characteristic based on a measurement result of a specific reproduction characteristic of the specific earphone. Regarding the {joint attachment characteristic correction calculation procedure} and {left and right earphone connection calculation procedure} defined in claim 1,
It is assumed that {the specific transfer characteristic of the {connection attachment} to be used} and {the transfer characteristic peculiarity of using the left and right earphones on the reproduction side and the detection side} are known in advance.
The characteristic that corrects the special characteristics of both transfer characteristics together is {joint attachment correction coefficient},
The characteristic obtained by multiplying the strength of {joint attachment correction coefficient} by {joint characteristic} for each frequency, or the characteristic obtained by adding the two in the case where both intensities are logarithmically expressed, is the {characteristic after joint attachment correction}
{{Calculation procedure for finding the square root of intensity at each frequency} of {{characteristic after bond attachment correction}} is {square root calculation procedure}
The {fifteenth pre-correction earphone characteristic calculation procedure} has at least a {square root calculation procedure} as a fifteenth feature,
The fourth feature defined in claim 1, that is, means for correcting both the special feature of {joint attachment} and the special feature of using the left and right earphones for reproduction and detection has the fifteenth feature. ,
An earphone characteristic correction method that corrects an inherent characteristic of the earphone to be close to {expected earphone reproduction characteristic} based on the measurement result of the characteristic characteristic of the earphone. Regarding the {earphone correction filter} defined in claim 1,
{Earphone correction filter} is a series of secondary filters that function in series.
Let each filter be eqi, where i is a number from 1 to m,
Each second-order filter has three parameters Pij, where j is 1, 2, and 3.
The sixteenth feature is that it has a {earphone correction filter} whose characteristics change according to i * j Pij.
{Earphone correction filter} intensity characteristic with respect to frequency is {correction characteristic}
The characteristic obtained by multiplying the intensity of {correction characteristic} and {earphone reproduction characteristic before correction} for each frequency is {earphone reproduction characteristic after correction},
Pmin-ij is a parameter group that determines the overall characteristics of the {earphone correction filter} where the difference between {expected earphone reproduction characteristics} and {correction characteristics} is minimal,
In order to obtain Pmin-ij, for all of Pij, {the function to adjust, verify, and determine} is {correction filter adjustment function},
It has the 17th feature of having {correcting filter adjustment function}
The {earphone correction filter} having the parameter group determined by the {correction filter adjustment function} receives the data of the music to be played by the music player as an input, so that the characteristic reproduction characteristics of the earphones can be {expected earphone reproduction characteristics The time-series encoded data converted into music data corrected to be corrected to the eighteenth feature,
The sixth feature defined in claim 1, that is, means for converting {pre-correction earphone reproduction characteristic} into {post-correction earphone reproduction characteristic} has sixteenth, seventeenth and eighteenth characteristics.
An earphone characteristic correction method for correcting a reproduction characteristic of an earphone so as to approach an expected reproduction characteristic based on a measurement result of a specific reproduction characteristic of the specific earphone. Regarding {joint attachment} as defined in claim 1,
In order to reduce the influence of the reflection of sound waves on the measurement result that occurs inside the {joint attachment}, the sound absorption of the tube that is part of the {joint attachment} structure is inserted. The element that has the effect is the {sound absorbing piece},
It has the nineteenth feature of having {sound absorbing piece}
The means for satisfying the first characteristic defined in claim 1, i.e., an attachment for acoustically coupling the left and right earphones, wherein the {combining attachment} used has the nineteenth characteristic. With regard to means for obtaining {acoustic coupling signal} as defined in claim 1,
Change the wiring from the earphone output terminal that outputs the {measurement signal} of the mobile terminal to the terminal of the {playback side earphone} and the connection from the {detection side earphone} terminal to the microphone input terminal of the mobile terminal Let the tool be {wiring conversion attachment},
The combination of {wiring conversion attachment} and {the {joint attachment} defined in claims 1 and 6} is a 20th feature,
A tool for measuring an inherent reproduction characteristic of an earphone having the twentieth feature as one of means for obtaining an {acoustic coupling signal} as defined in claim 1 The generation of the {measurement signal} defined in claim 1 functions on the OS of the {portable terminal} as a 21st feature,
The {voltage drop correction calculation procedure} defined in claim 2 or claim 3 functions on the OS of {portable terminal} according to the 22nd feature,
As defined in claims 1 and 4,
{Acoustic coupling correction calculation procedure} and {Right and left earphone coupling characteristic correction calculation procedure}
The 23rd feature is that it functions on the OS.
Means for satisfying the second, third, fourth and fifth features defined in claim 1;
Having the 21st, 22nd and 23rd features,
An application program for a portable terminal device having a signal processing procedure for measuring the unique characteristics of the earphone, which is a source of correcting the unique characteristics of the earphone to the expected reproduction characteristics. In order for the {correction filter} having the parameter group determined by the {correction filter adjustment function} defined in claim 5 to function on the OS of the {portable terminal},
It has a function to embed a parameter group determined by {correction filter adjustment function} in {correction filter}, having {correction filter},
The means for satisfying the sixth and seventh characteristics defined in claim 1 has a twenty-fourth characteristic.
An application program for a portable terminal having an acoustic data signal processing procedure for an earphone that corrects the inherent characteristic of the earphone obtained based on the measurement result to be close to the {expected earphone reproduction characteristic}.