JP3569175B2 - Frequency resolution measurement device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a frequency resolution measuring device that measures the frequency resolution of hearing.
[0002]
[Prior art]
Currently, the most frequently performed hearing characteristics tests for hearing-impaired persons are a hearing test (measurement of an audiogram) and a speech intelligibility test. In the hearing test, the frequency characteristics of the minimum audible threshold of the hearing-impaired person can be known, and in the speech intelligibility test, the hearing ability of the hearing-impaired person can be known.
However, since hearing characteristics of a hearing-impaired person vary from person to person, it is considered that only these two methods can grasp only one end of the complicated hearing characteristics.
[0003]
Generally, it is said that a hearing-impaired person has reduced frequency resolution in addition to reduced hearing ability and reduced ability to hear words. Here, the frequency resolution is the ability to distinguish two sounds having different frequencies. A normal hearing person can distinguish between two sounds whose frequencies are close to each other, for example, 1 kHz and 1.2 kHz, but a hearing-impaired person whose frequency resolution is reduced cannot distinguish these two sounds.
[0004]
When the degree of the decrease in the frequency resolution increases, the ability to hear words decreases, and the ability to discriminate speech under noise decreases. Knowing the degree of the decrease in the frequency resolution is very useful in diagnosing hearing loss, grasping the hearing characteristics of a hearing-impaired person, fitting a hearing aid, and the like.
[0005]
Conventionally, an auditory function testing device described in Japanese Patent No. 2723780 is known as this type of device. The auditory function testing apparatus includes a signal generation unit that generates a test sound including two types of notch noise and a detection sound by changing a ratio of a sound pressure of the detection sound to a sound pressure of the notch noise, and a test sound to the subject. Test sound output means for outputting, detection threshold detection means for detecting a detection threshold of a detection sound under the load condition of each of two types of notch noise of the subject, and two detection thresholds detected by the detection threshold detection means Calculation means for calculating the difference between the two.
[0006]
[Problems to be solved by the invention]
However, although this auditory function test apparatus can measure whether or not the frequency resolution is reduced in a relatively short time, there is a problem that it is often impossible to measure when the subject is a hearing-impaired person. Was. That is, the hearing function testing apparatus detects the minimum audible threshold of the signal sound after superimposing noise on the signal sound such as a pure tone.
However, the minimum audible threshold is naturally higher in a hearing-impaired person than in a normal hearing person, and furthermore, if notch noise is superimposed, the signal sound detection level threshold further increases. In addition, if the frequency resolution of the hearing-impaired person is deteriorated, the effect of the notch noise is greater than that of a normal hearing person. In many cases, the signal tone could not be detected (measurement impossible / scale out) even when the maximum output level was reached.
[0007]
The present invention has been made in view of such a problem with the conventional technology, and has as its object to measure the frequency resolution of hearing in a short time, and when the subject is a hearing-impaired person. It is intended to propose a frequency resolution measuring device which is hard to be unmeasurable.
[0008]
[Means for Solving the Problems]
In order to solve the above problem, the invention according to claim 1 adds a noise having a predetermined notch width generated from white noise set to a limit masking level to a detection sound having a frequency and a sound pressure level set to predetermined values. An addition unit that outputs the test sound output by the addition unit to the subject; a notch width setting unit that forms a notch having a desired notch width in the notch noise; A notch width display unit that displays a limit notch width at which the detected sound can be recognized is provided, and the subject can recognize the detected sound from the test sound while presenting the test sound to the subject and increasing the notch width of the notch noise. This is to obtain a limit notch width.
[0009]
Invention adds to the detected sound set frequency and sound pressure level to a predetermined value, test sound by adding the noise with a predetermined notch width generated from the white noise set a limit masking level according to claim 2 Unit, a receiver that presents the test sound output by the adding unit to the subject, a notch width setting unit that forms a notch of a desired notch width in the notch noise, and the subject can recognize the detection sound from the test sound. A notch width display unit that displays the limit notch width, and obtains a limit notch width at which the subject can recognize the detection sound from the test sound while presenting the test sound to the subject and increasing the notch width of the notch noise. It is.
[0010]
The invention according to claim 3 is the frequency resolution measuring device according to claim 1 or 2, wherein the sound pressure level of the detected sound is set to a minimum audible threshold of the subject or a sound pressure level obtained by adding a predetermined level to the minimum audible threshold. It is set.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Here, FIG. 1 is a configuration diagram of a frequency resolution measuring apparatus according to the present invention, FIG. 2 is a flowchart similarly, FIG. 3 is a conceptual diagram of a test sound, and FIG. 4 is a physical model representing human auditory frequency resolution. FIG.
[0012]
As shown in FIG. 1, the frequency resolution measuring device according to the present invention includes a noise generation unit 1, a noise level setting unit 2, a notch width setting unit 3, a detected sound signal generation unit 4, a detected sound signal level setting unit 5, an addition. It comprises a unit 6, a receiver 7, a notch width display unit 8, and the like.
The noise generator 1 has a function of outputting a noise signal, for example, a white noise signal.
[0013]
The noise level setting unit 2 has a function of setting the level of the noise signal output by the noise generation unit 1 to a calibrated level and displaying the level of the sound pressure output by the handset 7. Here, the calibrated level refers to the level of a signal that attaches an acoustic load such as a coupler to the receiver 7 and generates a desired sound pressure on the acoustic load. For example, when the calibration level is set so that the display becomes Ln [dBSPL], the noise level setting unit 2 generates an output level noise such that a sound pressure of Ln [dBSPL] is generated per 1 [Hz] on the acoustic load. Is output.
[0014]
The notch width setting unit 3 has a function of forming a notch having a desired notch width with a desired frequency as a center frequency in a noise signal output from the noise level setting unit 2 and an electric signal indicating a value of the notch width at that time. Is output to the outside.
The detection sound signal generator 4 has a function of outputting a detection sound signal, that is, a sine wave signal of a predetermined frequency.
[0015]
The detection sound signal level setting unit 5 has a function of setting the detection sound signal output by the detection sound signal generation unit 4 to a calibrated level and displaying the level of the sound pressure output by the handset 7. Here, the calibrated level refers to the level of a signal that attaches an acoustic load such as a coupler to the receiver 7 and generates a desired sound pressure on the acoustic load. For example, when the calibration level is set so that the display becomes Ld [dBSPL], the detection sound signal level setting unit 5 outputs a detection sound signal having an output level such that a sound pressure of Ld [dBSPL] is generated in the acoustic load. Output.
[0016]
The addition unit 6 has a function of adding (superimposing) a noise signal output from the notch width setting unit 3 and a sine wave signal (detection sound signal) output from the detection sound signal level setting unit 5 to generate an inspection sound signal. Have.
[0017]
The receiver 7 has a function of performing electroacoustic conversion on the electric signal (test sound signal) output from the adding unit 6 and outputting an acoustic signal based on the electric signal as a test sound.
The notch width display section 8 has a function of displaying the notch width based on an electric signal corresponding to the notch width output from the notch width setting section 3.
[0018]
The operation of the frequency resolution measuring device configured as described above will be described with reference to the flowchart shown in FIG.
First, in step SP1, the operator operates the detection sound signal generation unit 4 to set the frequency of the detection sound signal output from the detection sound signal generation unit 4 to the frequency f at which the frequency resolution is to be measured. At this time, the switch Sw1 is turned off to prevent the noise signal output from the notch width setting unit 3 from being input to the adding unit 6. The switch Sw2 is turned off in order to prevent noise accompanying the adjustment from being output from the receiver 7.
[0019]
Next, in step SP2, the operator operates the detected sound signal level setting unit 5 to set the sound pressure of the detected sound output from the receiver 7 to the minimum audible threshold T [dBSPL] of the subject.
In the case of this embodiment, when setting the sound pressure of the detected sound to the minimum audible threshold value of the subject, a so-called limit method is used. That is, first, the detection sound signal level setting unit 5 is operated to adjust the output of the detection sound signal level setting unit 5 to a sufficiently small value. Thereafter, the switch Sw2 is turned on, and the detection sound is presented to the subject.
[0020]
When the subject signals that the detected sound cannot be heard at this time, the operator operates the detected sound signal level setting unit 5 to slightly increase the detected sound signal level, and again outputs the test sound to the subject. Present. This operation is repeated until a signal indicating that the subject has heard is obtained. When there is a signal indicating that the user has been heard, the step SP2 ends.
When step SP2 ends, the level of the detected sound signal output by the detected sound signal level setting unit 5 is set to the minimum audible threshold T [dBSPL] of the subject.
[0021]
Next, in step SP3, the notch width setting unit 3 is operated to set the notch width of the notch noise output from the noise level setting unit 2 to 0. Thus, the notch width setting unit 3 outputs a white noise signal.
[0022]
Next, in step SP4, the level of the white noise signal output from the noise level setting unit 2 is set to the limit masking level. Here, the limit masking level refers to a limit level at which a sound obtained by adding white noise to a detected sound is presented to the subject, and whether or not the subject can perceive the detected sound.
[0023]
In the case of this embodiment, the limit method is used to set the limit masking level. That is, first, the noise level setting unit 2 is operated to sufficiently reduce the level of the white noise signal output from the noise level setting unit 2. Thereafter, the switch Sw1 and the switch Sw2 are turned on, and the sound obtained by adding the detected sound and the white noise is presented to the subject. The noise level setting unit 2 is operated to increase the level of the white noise signal until the subject cannot perceive the detected sound from the sound obtained by adding the detected sound and the white noise.
[0024]
Next, in step SP5, the notch width setting unit 3 is operated to add a predetermined notch width, for example, a notch having a notch width g = 0.05, to the white noise signal output from the notch width setting unit 3 to generate noise. I do. Here, the notch width g is represented by g = Δf / fc. Here, Δf is the frequency from the noise to the test sound. In addition, fc is the center frequency of the notch, which is made to match the frequency f of the detected sound signal generation unit 4 set in step SP1.
[0025]
FIG. 3 shows the frequency spectrum of the test sound signal obtained in steps SP1 to SP5 up to here, that is, the output signal (detected sound signal + noise signal) of the adder 6.
[0026]
Next, in step SP6, the receiver 7 performs electroacoustic conversion of the test sound signal output by the adder 6, and presents a test sound based on the test sound signal to the subject.
[0027]
Next, in step SP7, it is determined whether or not the subject has heard the detected sound in the test sound. That is, the operator inquires of the subject whether or not he / she has heard the detection sound during the test sound. When the subject cannot perceive that the detection sound is included in the inspection sound, the process proceeds to step SP8, and the notch width g is increased by a predetermined width.
[0028]
Next, the process returns to step SP6 and presents the test sound to the subject. Then, the processing of step SP8, step SP6, and step SP7 is repeated until the subject can perceive that the detection sound includes the detection sound. That is, the limit notch width (limit notch width g ′) for determining whether or not the subject can perceive the detection sound in the test sound is obtained based on the limit method.
[0029]
In step SP7, if the subject can perceive the detection sound during the test sound, the process proceeds to step SP9, where the operator reads the limit notch width g 'displayed by the notch width display unit 9, and if necessary, sets the value to this value. Is recorded, and the frequency resolution measurement ends.
[0030]
As a physical model representing the frequency resolution of human hearing, a filter bank having characteristics as shown in FIG. 4, that is, a filter device that constitutes one bandpass filter by combining a plurality of narrowband filters has been proposed. . In FIG. 4, when the width of the narrow-band filter is large (dotted line), it is a human auditory model with reduced frequency resolution, and when the width is small (solid line), it is a human auditory model with normal frequency resolution. Is represented. The thick solid line indicates the auditory filter that has reacted.
[0031]
The limit notch width g ′ obtained in step SP9 represents the extent of the width expansion of the narrow band filter constituting the human hearing with the center frequency f, that is, the frequency resolution of hearing at the measurement frequency f. It is believed to represent. When the value of the limit notch width g 'is large, it means that the width of the narrow band filter constituting the human hearing is widening, and conversely, it is not wide. Experiments have shown that the critical notch width g 'agrees with a value representing the frequency resolution of hearing with considerable accuracy.
[0032]
In step SP2 of the above-described embodiment, the case where the level T [dBSPL] corresponding to the minimum audible threshold of the subject is used as the detected sound level x [dBSPL], but the present invention is not limited to this. Instead, the level of the detected sound may be slightly increased from the level corresponding to the test subject's minimum audible threshold T [dBSPL], or for example, x = T + 5 [dBSPL].
[0033]
When this measurement is performed with the level of the detected sound set to the minimum audible threshold of the subject, the detected sound signal level becomes the detection limit level, so it can be determined whether or not the detected sound in the test sound can be perceived. Can be very difficult. By making the level of the detected sound somewhat higher than the level corresponding to the test subject's minimum audible threshold, the test subject can easily determine.
[0034]
In the above-described embodiment, the frequency f of the detected sound signal output from the detected sound signal generation unit 4 and the center frequency fc of the notch noise set by the notch width setting unit 3 are matched (f = fc). Although the case has been described, it is not always necessary to make them coincide with each other, as long as the detected sound signal is included within the notch width.
[0035]
Furthermore, in the above-described embodiment, when obtaining the limit notch width g ′ of the subject, the notch width g of the notch noise is first set to be narrow to present the test sound, and the test subject cannot perceive the detection sound from the test sound. In this case, the procedure of gradually increasing the notch width g of the notch noise and presenting the inspection sound again has been described.
However, since the limit notch width g 'may be determined, the notch noise g of the notch noise is set to a large value to present the test sound, and when the subject can perceive the detection sound from the test sound, the notch noise gradually increases. May be reduced.
[0036]
In the above-described embodiment, the case where the limit method is used for setting the level of the detected sound (step SP2) and setting the limit masking level (step SP4) has been described. Alternatively, the setting may be made based on a psychophysical measurement method such as a two-alternative forced choice method in which the sound is selected from any of the test sounds to which the detection sound is not added.
[0037]
Furthermore, in the above-described embodiment, the case where the limit notch width g ′ is obtained by using the limit method has been described. However, the limit notch width g ′ may be obtained based on a psychophysical measurement method such as a two-way compulsory selection method.
[0038]
【The invention's effect】
As described above, according to the first aspect of the invention, the frequency resolution of hearing can be easily measured.
[0039]
According to the invention of claim 2, the frequency resolution of hearing can be easily measured.
[0040]
According to the invention according to claim 3, it is possible to easily determine whether or not the subject has detected the detected sound signal, and the test apparatus cannot measure even a person with a high / severe hearing loss having a high minimum audible threshold. It is possible to measure the frequency resolution of the auditory sense without becoming irrelevant.
[Brief description of the drawings]
1 is a block diagram of a frequency resolution measuring device according to the present invention; FIG. 2 is a flowchart of a frequency resolution measuring device according to the present invention; FIG. 3 is a conceptual diagram of a test sound used in the frequency resolution measuring device according to the present invention; 4) Physical model diagram showing human hearing frequency resolution [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Noise generation part, 2 ... Noise level setting part, 3 ... Notch width setting part, 4 ... Detection sound signal generation part, 5 ... Detection sound signal level setting part, 6 ... Addition part, 7 ... Handset, 8 ... Notch width Display section.

Claims (3)

The detected sound set frequency and sound pressure level to a predetermined value, an adding unit to test sound by adding the noise with a predetermined notch width generated from the white noise set a limit masking level, the adding portion and the output A handset that presents a test sound to be tested to a subject, a notch width setting unit that forms a notch of a desired notch width in the notch noise, and a notch that displays a limit notch width at which the subject can recognize the detected sound from the test sound A frequency resolution measuring device comprising a width display unit, wherein the test sound is presented to the subject to increase the notch width of the notch noise, and the subject obtains a limit notch width at which the test sound can be recognized from the test sound. . The detected sound set frequency and sound pressure level to a predetermined value, an adding unit to test sound by adding the noise with a predetermined notch width generated from the white noise set a limit masking level, the adding portion and the output A handset that presents a test sound to be tested to a subject, a notch width setting unit that forms a notch of a desired notch width in the notch noise, and a notch that displays a limit notch width at which the subject can recognize the detected sound from the test sound A frequency resolution measuring device comprising a width display unit, wherein the test sound is presented to the subject to increase the notch width of the notch noise, and the subject obtains a limit notch width at which the test sound can be recognized from the test sound. . 3. The frequency resolution measuring device according to claim 1, wherein the sound pressure level of the detected sound is set to a minimum audible threshold of the subject or a sound pressure level obtained by adding a predetermined level to the minimum audible threshold.

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