JP5340121B2 - Audio signal playback device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an audio signal reproducing apparatus capable of obtaining a sufficient sense of low-pitched sound even when sound volume setting of the reproducing apparatus is small amount of sound volume, and obtaining a fixed sense of low-pitched sound regardless of sound volume. <P>SOLUTION: A low-pitched sound component extracting section 2 extracts a low-pitched sound component signal from an input signal, a high harmonic wave generating section 3 generates a high harmonic wave component signal from the low-pitched sound component signal and an adder 5 adds the high harmonic wave component signal and the input signal, thereby a sufficient sense of low-pitched sound can be obtained even when sound volume setting of a reproducing apparatus is small amount of sound volume. Furthermore, a gain control section 8 calculates a gain value corresponding to a lowest resonance frequency and set volume of a speaker based on an equal-loudness curve and a high harmonic wave gain adjusting section 4 uses the gain value to perform gain adjustment of the high harmonic wave component signal, thereby a fixed sense of low-pitched sound can be obtained regardless of sound volume. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an audio signal reproducing apparatus that enhances the low-frequency feeling of an audio signal.

  In recent years, since the casing of a liquid crystal television is thinned, a speaker built in the casing is also downsized. When reproducing an audio signal using such a small speaker, it is difficult to obtain a sufficient low-frequency sound. As a technique for obtaining a sufficient low-frequency feeling even with a small speaker, there is a technique for creating a low-pitched sound in a pseudo manner using the psychoacoustic feature “Missing fundamental”. Here, “missing fundamental” is a feature that gives an illusion that when a listener hears sound of two or more frequencies at the same time, the difference sound is heard.

  An audio signal processing device using this “Missing fundamental” is proposed in Patent Document 1, for example. In this audio signal processing apparatus, a low frequency component is extracted from the audio signal, a harmonic component signal is generated from the low frequency component, and then the harmonic component signal is added to the audio signal from which the low frequency component has been cut to obtain an output signal. Accordingly, even if the output signal does not include a bass component that is difficult to be reproduced by a small speaker, an illusion can be given when the bass component is heard by the harmonic component signal generated from the bass component.

  Further, in this audio signal processing device, the amplitude value of the output signal is compared with a threshold value, and when it is equal to or larger than the threshold value, the gain value to be multiplied by the harmonic component is reduced, and when it is smaller than the threshold value, the gain value is increased. Take control. Thus, clipping of the output signal is suppressed on the playback device side including a small speaker, an amplifier, and the like.

JP 2009-44268 A (FIG. 1)

In general, the sensitivity of human auditory sensation varies depending on the frequency band. In particular, the sensitivity of bass sounds is low, and the lower the volume, the more difficult it is to hear bass sounds. For this reason, when an audio signal is reproduced at a low volume, it is heard with less power.
The audio signal processing device according to Patent Document 1 has a function of changing the gain value of the generated harmonic component signal according to the amplitude value of the input audio signal, but the gain is changed according to the volume of the playback device. Therefore, there is a problem that the lower the sound volume, the lower the perception of bass due to the above-mentioned human auditory characteristics. In addition, there is a problem that the low-frequency sound obtained varies depending on the sound volume.

  The present invention has been made to solve the above-described problems, and provides a sufficient low-frequency feeling even when the volume setting of the playback device is low, and a constant low-frequency feeling is obtained regardless of the volume. It is an object of the present invention to provide an audio signal reproducing apparatus obtained.

  An audio signal reproduction device according to the present invention includes a bass component extraction unit that extracts a bass component signal from an input signal, a harmonic generation unit that generates a harmonic component signal from the bass component signal extracted by the bass component extraction unit, A harmonic gain adjustment unit that adjusts the gain of the harmonic component signal generated by the wave generation unit, and the harmonic component signal that has been gain-adjusted by the harmonic gain adjustment unit and the input signal are added to generate an effect-added signal. Generated by the harmonic generation unit according to the volume gain adjustment unit for adjusting the gain of the effect applying signal generated by the adder, speaker information representing the characteristics of the speaker, and the set volume of the speaker. A gain control unit that calculates a gain value to be multiplied by the harmonic component signal and outputs the gain value to the harmonic gain adjustment unit, and a gain value that is multiplied by the effect applying signal generated by the adder according to the set volume Calculated, in which and a volume control unit for outputting to the volume gain adjustment unit.

  According to the present invention, a harmonic component signal is generated from the bass component signal extracted from the input signal, and the harmonic component signal is multiplied by the gain value corresponding to the speaker information and the set volume, and the gain-adjusted harmonic is generated. Since the effect signal is generated by adding the component signal and the input signal, even when the volume setting of the playback device is low, a sufficient bass feeling can be obtained with the harmonic component signal, and the harmonics It is possible to provide an audio signal reproducing apparatus that can obtain a constant low-frequency feeling regardless of the volume by adjusting the gain of the component signal.

1 is a block diagram showing a configuration of an audio signal reproduction device according to Embodiment 1 of the present invention. 3 is a flowchart showing an operation of the audio signal reproduction device shown in FIG. 1. It is a graph explaining the gain value setting method of the gain control part 8 shown in FIG. 1, and shows the case where the volume is lowered. It is a graph explaining the gain value setting method of the gain control part 8 shown in FIG. 1, and shows the case where a volume is raised. It is a graph explaining the gain value setting method of the gain control part 8 shown in FIG. 1, and shows the relationship between a volume fluctuation | variation and a gain value. It is a graph explaining the gain value setting method of the gain control part 8 in the audio signal reproducing | regenerating apparatus concerning Embodiment 2 of this invention, and shows the case where a volume is small. It is a graph explaining the gain value setting method of the gain control part 8 in the audio signal reproducing | regenerating apparatus concerning Embodiment 2 of this invention, and shows the case where a volume is large. It is a figure which shows an example of the speaker information which the speaker information storage part 1 of the audio signal reproduction apparatus which concerns on Embodiment 3 of this invention stores. It is a block diagram which shows the structure of the audio signal reproducing | regenerating apparatus based on Embodiment 4 of this invention. 10 is a flowchart showing an operation of the audio signal reproduction device shown in FIG. 9.

Embodiment 1 FIG.
The audio signal reproduction device shown in FIG. 1 uses an audio signal as an input signal to generate an output signal that has been subjected to processing described later, and outputs it to a speaker (not shown) for reproduction. This audio signal reproduction apparatus includes a speaker information storage unit 1 that stores information on the lowest resonance frequency f ₀ of the speaker as speaker information, a bass component extraction unit 2 that extracts a bass component signal from an input signal, and an extracted bass component signal A harmonic generation unit 3 that generates a higher harmonic component signal, a harmonic gain adjustment unit 4 that is a multiplier that adjusts the gain of the harmonic component signal, and a gain-adjusted harmonic component signal and an input signal are added. An adder 5 that generates an effect applying signal, a volume gain adjusting unit 6 that is a multiplier that multiplies the effect applying signal by a gain corresponding to the set volume, and a set volume value that the speaker reproduces is received and stored as volume information. A volume information storage unit 7 and a volume control unit 9 that calculates a gain multiplied by the volume gain adjustment unit 6 based on the speaker information and the volume information are configured.

Next, details of each unit will be described according to the flowchart of the audio signal reproducing device shown in FIG. When the audio signal reproduction device starts operation, the speaker information storage unit 1 stores in advance the lowest resonance frequency f ₀ of the speaker as speaker information, and the speaker information is stored in the bass component extraction unit 2 and the speaker information as necessary. Output to the gain controller 8. The volume information storage unit 7 accepts the set volume value and stores it as volume information, and outputs the volume information to the gain control unit 8 and the volume control unit 9 as necessary.

In step ST1, when an input signal is input, the bass component extraction unit 2 acquires speaker information from the speaker information storage unit 1, and inputs a bass component signal including a bass component having a frequency equal to or lower than the lowest resonance frequency f _{0 of the} speaker. And output to the harmonic generation unit 3.
For example, if the lowest resonance frequency _{f 0} of the speaker is 100Hz, the bass component signal consisting of bass components 100Hz is generated.

  In step ST <b> 2, the harmonic generation unit 3 generates a harmonic component signal based on the bass component signal of the bass component extraction unit 2 and outputs the harmonic component signal to the harmonic gain adjustment unit 4. The harmonic generation method of the harmonic generation unit 3 may be any method that generates a harmonic component signal that follows the power of the bass component signal. Waveform modifications such as peak hold, full-wave rectification, and half-wave rectification are possible. This is the generation method used.

In step ST3, the harmonic gain adjustment unit 4 confirms whether the set volume has been changed based on the volume information in the volume information storage unit 7.
When the set volume has not been changed (step ST3 “NO”), the harmonic gain adjustment unit 4 uses the gain value output from the gain control unit 8 as the harmonic component signal of the harmonic generation unit 3 in step ST4. The harmonic component signal multiplied and gain-adjusted is output to the adder 5. In subsequent step ST <b> 5, the adder 5 adds the harmonic component signal gain-adjusted by the harmonic gain adjustment unit 4 to the input signal to generate an effect imparting signal, and outputs the signal to the volume gain adjustment unit 6. In subsequent step ST6, the sound volume gain adjusting unit 6 multiplies the effect applying signal of the adder 5 by the gain value output from the sound volume controlling unit 9, and outputs the gain adjusted effect applying signal as an output signal.

Next, a case where the set volume is changed will be described (step ST3 “YES”).
Gain controller 8 in step ST7 is, the speaker information from the speaker information storage unit 1, respectively obtains the volume information from the volume information storage unit 7, the harmonic gain adjusting unit 4 on the basis of the volume setting and the lowest resonance frequency f ₀ Then, a gain value for multiplying the harmonic component signal is calculated and output to the harmonic gain adjustment unit 4. In subsequent step ST4, the harmonic gain adjustment unit 4 multiplies the harmonic component signal by the newly calculated gain value.

The gain value that the harmonic gain adjustment unit 4 multiplies the harmonic component signal is set to a value that always provides a constant low tone even when the set volume is changed. Hereinafter, a specific setting method will be described based on the equal loudness curve shown in FIG. In the graph of FIG. 3, the vertical axis indicates the sound pressure level [dB], and the horizontal axis indicates the frequency [Hz]. In this example, the sound pressure level of 60 phones is set as the reference volume, the solid line is an equal loudness curve at the reference volume, the broken line is a curve obtained by translating the equal loudness curve by −20 dB, and the alternate long and short dash line is the set volume from the reference volume to 20 dB. A lowered equal loudness curve is shown. Here, in order to lower the set sound volume by 20 dB from the reference sound volume, if the sound pressure level of the equal loudness curve shown by a solid line is adjusted by -20 dB lowering the frequency uniformly and moved downward, the curve shown by a broken line become.
However, as described above, the sensitivity of human hearing varies depending on the frequency band, and in particular, the sensitivity of bass sounds is dull. The lower the volume, the harder it is to hear, so 100 Hz bass sounds as 1 kHz sound. It is perceived that the size is reduced by adding 5.7 dB (that is, 25.7 dB).
Accordingly, it is desirable to adjust the sound pressure level of the bass component based on the equal loudness curve indicated by the alternate long and short dash line, instead of adjusting the sound pressure level uniformly for each frequency so as to obtain the curve indicated by the broken line. Accordingly, when the lowest resonance frequency f ₀ (100 Hz in this case) of the speaker is set as a reference frequency, the gain value multiplied by the harmonic component signal by the harmonic gain adjusting unit 4 from the equal loudness curve is the fluctuation of the reference volume and the set volume. The gain value should be +5.7 dB larger than the volume (−20 dB).

Next, a gain value setting method when the set volume is raised from the reference volume will be described based on the equal loudness curve shown in FIG. In the graph of FIG. 4, the vertical axis represents the sound pressure level (dB) and the horizontal axis represents the frequency (Hz). In this example as well, the sound pressure level of 60 phones is set as the reference volume, the solid line is an equal loudness curve at the reference volume, the broken line is a curve obtained by translating the equal loudness curve by +20 dB, and the alternate long and short dash line is the set volume increased by 20 dB from the reference volume. Shows an equal loudness curve.
When the set sound volume is uniformly increased by 20 dB from the reference sound volume, it is perceived that the low frequency of 100 Hz is increased by 6.2 dB (ie, increased by 26.2 dB) compared to the sound of 1 kHz. Therefore, assuming that the lowest resonance frequency f ₀ (100 Hz in this case) of the speaker is the reference frequency, the gain value multiplied by the harmonic component signal by the harmonic gain adjustment unit 4 from the equal loudness curve is the fluctuation volume of the reference volume and the set volume. A gain value smaller than (+20 dB) by −6.2 dB is preferable.

  As described with reference to FIGS. 3 and 4, the gain control unit 8 sets an arbitrary volume as a reference volume in advance, and when the set volume is smaller than the reference volume, the reference volume and the change volume of the set volume are set. A larger gain value is obtained. On the other hand, if the set sound volume is larger than the reference sound volume, a gain value smaller than the fluctuation sound volume is obtained.

Further, the gain control unit 8 may use a method other than the above-described gain value setting method. The graph of FIG. 5 is a graph summarizing the relationship between the change volume (set volume−reference volume) and the gain value when the set volume is changed from the reference volume, the vertical axis is gain [dB], and the horizontal axis is variable. Indicates volume [dB]. In FIG. 5, the dotted line indicates a broken line of the reading values of the fluctuation sound volume and the gain value, the alternate long and short dash line indicates a straight line obtained by approximating the read value with a linear function, and the solid line indicates a curve obtained by approximating the read value with a quartic function. The order of function approximation may be selected arbitrarily in accordance with the design specifications of the audio signal reproduction device. The following formulas (1) and (2) show examples of functions calculated by performing polynomial approximation by the least square method for the case of the linear function and the quartic function. However, since there is no gain fluctuation when there is no volume fluctuation from the reference volume, the constant term of the approximate polynomial is set to zero.
G = −0.2750v (1)
G = -1.993 × 10 ⁻⁶ v ⁴ −3.2547 × 10 ⁻⁵ v ³
+ 0.00125426v ² -0.27538v (2)
Here, G is a gain value [dB], and v is a fluctuation volume [dB] from the reference volume.

  In this example, a polynomial is used for function approximation, but the present invention is not limited to this, and a radial basis function or the like may be used.

As described with reference to FIG. 5, the gain control unit 8 has information on a function that approximates the relationship between the change volume and the gain value when the set volume is changed from the reference volume, according to the change volume. The gain value is calculated from the function.
It should be noted that the gain control unit 8 has a plurality of functions, and selects a fourth-order approximation function when the fluctuation volume from the reference volume is smaller than −30 dB, and selects a first-order approximation function when it is larger. The gain value may be calculated by changing the function according to the fluctuation volume from the volume.

In step ST8, the volume control unit 9 acquires volume information from the volume information storage unit 7, calculates a gain value for multiplying the effect applying signal by the volume gain adjustment unit 6 based on the set volume, and adjusts the volume gain. Output to unit 6. Unlike the gain control unit 8 that calculates the gain value based on the equal loudness curve, the volume control unit 9 calculates the gain value only from the set volume of the playback device and outputs a bass component having the lowest resonance frequency f ₀ or less. Gain adjustment is performed uniformly for all the frequency bands including it. The volume control unit 9 prepares a gain value corresponding to the set volume of the playback device stored in the volume information storage unit 7 as a preset table and sets the gain value in the volume control unit 9. A gain value corresponding to (volume information) may be selected from this table.
In subsequent step ST6, the sound volume gain adjustment unit 6 multiplies the effect applying signal by the newly calculated gain value.
The audio signal reproduction device generates an output signal by repeating the above series of processing.

As described above, according to the first embodiment, the audio signal reproduction device is configured to extract the harmonic component signal from the bass component extraction unit 2 that extracts the bass component signal from the input signal and the bass component signal extracted by the bass component extraction unit 2. A harmonic generation unit 3 to be generated, a harmonic gain adjustment unit 4 that performs gain adjustment of the harmonic component signal generated by the harmonic generation unit 3, and a harmonic component signal that has been gain-adjusted by the harmonic gain adjustment unit 4; An adder 5 for adding an input signal to generate an effect applying signal, a volume gain adjusting unit 6 for adjusting the gain of the effect applying signal generated by the adder 5, and a minimum resonance frequency f ₀ representing the characteristics of the speaker. A speaker information storage unit 1 that stores the speaker information, a volume information storage unit 7 that acquires the set volume of the speaker as volume information, and a harmonic component signal that is multiplied according to the speaker information and the volume information A gain control unit 8 that calculates a gain value to be output and outputs the gain value to the harmonic gain adjustment unit 4; and a volume control unit that calculates a gain value to be multiplied by the effect applying signal according to the volume information and outputs the gain value to the volume gain adjustment unit 6 9 and so on. For this reason, since the effect component signal is generated by adding the harmonic component signal of the bass component signal obtained by extracting the bass component having the lowest resonance frequency f ₀ or less of the speaker from the input signal to the input signal, the speaker generates the lowest resonance frequency f. _Even if it is difficult to reproduce a bass sound of ₀ or less, a low-pitched feeling can be obtained in a pseudo manner by the harmonic component.

Further, according to the first embodiment, the gain control unit 8 sets the predetermined volume as the reference volume, and when the set volume is larger than the reference volume, the gain is set to be smaller than the fluctuation volume from the reference volume to the set volume. Thus, when the set volume is lower than this reference volume, the lowest resonance frequency is based on the equal loudness curve of the reference volume and each set volume so that the gain is larger than the fluctuation volume from the reference volume to the set volume. and configured to calculate a gain value at f _0. Further, this relationship is approximated by a function, and the function is set in the gain control unit 8 in advance. For this reason, even when the set volume is changed by changing the gain value by which the gain control unit 8 multiplies the harmonic component signal according to the fluctuation volume from the reference volume based on the equal loudness curve. A low-pitched feeling can be obtained, and even if the set volume is small, the low-pitched feeling is not diluted. Further, since the gain value of the harmonic component signal is reduced when the set volume is high, it is possible to prevent deterioration in the quality of the reproduced sound due to clipping of the output signal by the speaker.

Embodiment 2. FIG.
The audio signal reproducing apparatus according to the second embodiment has the same configuration as that shown in FIG. 1 and the operation thereof is also the same as that shown in the flowchart of FIG. Embodiment 2 will be described.

  When the adder 5 adds the input signal and the gain-adjusted harmonic component signal in step ST5, if the input signal is small, the ratio of the harmonic component signal is larger than the input signal. May increase the sense of distortion, and sound quality may deteriorate. Therefore, in order to prevent this, when the gain control unit 8 calculates a gain value to multiply the high-frequency component signal (step ST7), if the calculated gain value exceeds an arbitrary threshold value, this threshold value is set to the gain value. To.

The graph of FIG. 6 is a graph summarizing the relationship between the change volume (set volume−reference volume) and the gain value when the set volume is changed from the reference volume. The vertical axis represents the gain [dB] and the horizontal axis represents the fluctuation. Indicates volume [dB]. A dotted line indicates a broken line of the reading values of the fluctuation sound volume and the gain value, and a solid line indicates a broken line obtained by combining a straight line obtained by approximating the reading value with a linear function and a threshold of +8 dB.
The gain control unit 8 has linear function information and threshold value information as shown in FIG. 6, and when the set sound volume is large and the gain value calculated from the linear function does not exceed the threshold value, the gain value is increased. On the other hand, when the set sound volume is small and the gain value calculated from the linear function exceeds the threshold value, the threshold value is output to the harmonic gain adjustment unit 4.

  In addition, when the input signal and the harmonic component signal whose gain has been adjusted are added, if the set volume of the playback device is large, the output signal played back by the speaker may be distorted. Therefore, in order to prevent sound quality deterioration due to distortion, the output signal reproduced from the speaker is collected using a microphone or the like, and the distortion rate with the input signal is measured, and the gain control unit 8 responds to the distortion rate. Change the gain value. The change point for changing the gain value is that the output signal is clipped when the set sound volume is increased, and the distortion rate suddenly increases. Therefore, the change point may be changed according to the characteristics of the speaker. Then, when the gain control unit 8 calculates a gain value to be multiplied by the high frequency component signal (step ST7), the gain control unit 8 sets the gain value to a smaller value or 0 at the change point.

The graph of FIG. 7 is a graph for explaining a gain value setting method when the distortion rate suddenly increases when the set volume is changed from the reference volume when the changed volume (set volume−reference volume) is +10 dB. The vertical axis represents gain [dB], and the horizontal axis represents variable volume [dB]. A dotted line indicates a broken line of the reading values of the fluctuation sound volume and the gain value, and a solid line indicates a straight line obtained by approximating the reading values by a linear function. In this example, assuming that the output signal is clipped and the distortion rate suddenly increases when the fluctuation volume becomes +10 dB, +10 dB is set as the change point. Therefore, the gain value indicated by the solid line is 0 dB (A in FIG. 7) or smaller value (B in FIG. 7) if it is larger than +10 dB, and approximates a function with a linear function if it is smaller than +10 dB. The value follows the straight line.
The gain control unit 8 has linear function information as shown in FIG. 7, information on a change point corresponding to the characteristics of the speaker, and information on a gain value when the fluctuation volume is larger than the change point. When the control unit 8 calculates a gain value to multiply the high-frequency component signal (step ST7), if the set volume is small and the variable volume is smaller than the change point, the gain value is calculated from a linear function. When the volume is large and the fluctuation volume is larger than the change point, a gain value smaller than the gain value calculated from the linear function is calculated, or 0 is selected and output to the harmonic gain adjustment unit 4 .

In the illustrated example, the threshold value is combined with the method of calculating the gain value from the straight line approximated by the linear function in the gain value setting method described in the first embodiment. However, the present invention is not limited to this. Instead, the configuration may be such that the threshold is combined with the other gain value setting method described in the first embodiment.
Moreover, the structure which combines the gain value setting method demonstrated using FIG.6 and FIG.7 may be sufficient.

  As described above, according to the second embodiment, the gain control unit 8 outputs the threshold value to the harmonic gain adjustment unit 4 instead of the gain value when the calculated gain value exceeds the predetermined threshold value. Configured. For this reason, when the set volume is low, the gain value of the harmonic component signal can be made constant, so when adding the harmonic component signal to the input signal, the ratio of the harmonic component signal is suppressed to a constant amount, and a low-pitched feel is achieved. While obtaining, it can weaken the sense of distortion and prevent deterioration of sound quality.

  Further, according to the second embodiment, the gain control unit 8 is configured to adjust the calculated gain value according to the speaker characteristics. For this reason, when the set sound volume is high, the gain value of the harmonic component signal can be reduced. Therefore, when the harmonic component signal is added to the input signal, the sound quality deterioration of the reproduced sound due to clipping of the output signal by the speaker is prevented. be able to.

Embodiment 3 FIG.
The audio signal reproducing apparatus according to the third embodiment has the same configuration as that shown in FIG. 1 and the operation thereof is the same as that shown in the flowchart of FIG. A third embodiment will be described.

In this audio signal reproducing apparatus, the speaker information storage unit 1 stores the minimum resonance frequency f ₀ of a plurality of speakers as shown in FIG. 8 as speaker information in a table. However, it is not necessary for all the plurality of speakers to be connected to the audio signal reproducing device, and speaker information of speakers that may be connected may be set in advance. The speaker information storage unit 1 outputs the speaker information of the speaker, that is, the speaker identification index and the lowest resonance frequency f ₀ to the bass component extraction unit 2 and the gain control unit 8 according to the speaker to be connected.

In step ST1, the bass component extraction unit 2 acquires the speaker information of the speaker from the speaker information storage unit 1 according to the speaker to be connected, and the bass component signal including the bass component having the lowest resonance frequency f ₀ or less for each speaker. Is extracted from the input signal and output to the harmonic generation unit 3.

In step ST7, the gain control unit 8 acquires the speaker information of the speaker from the speaker information storage unit 1 according to the connected speaker, acquires the volume information from the volume information storage unit 7, and corresponds to the speaker information. Based on the lowest resonance frequency f ₀ of the speaker with the index to be set and the set volume, the gain value for multiplying the harmonic component signal by the harmonic gain adjusting unit 4 is calculated and output to the harmonic gain adjusting unit 4.
Note that the gain value setting method by the gain control unit 8 may be the method described in the first embodiment or a combination of the methods described in the first and second embodiments.

As described above, according to the third embodiment, the speaker information storage unit 1 stores table information including the lowest resonance frequencies f ₀ of a plurality of speakers as speaker information, and the bass component extraction unit 2 stores the information for each speaker. In addition, a frequency band having the lowest resonance frequency f ₀ or less is extracted as a bass component signal. For this reason, a process can be changed appropriately according to a connected speaker, and even if the set sound volume of the playback device fluctuates, a certain low-pitched feeling can be obtained.

Embodiment 4 FIG.
FIG. 9 shows the configuration of the audio signal reproduction apparatus according to the fourth embodiment. The same or corresponding parts as those in FIG. The audio signal reproduction device shown in FIG. 9 newly includes a fundamental frequency detection unit 10 and refers to the lowest resonance frequency f ₀ of the speaker when the gain control unit 8 calculates a gain value to be multiplied by the harmonic component signal. Instead, the fundamental frequency detector 10 refers to the fundamental frequency detected from the bass component signal.

Next, details of the fundamental frequency detector 10 will be described according to the flowchart of the audio signal reproducing device shown in FIG. In FIG. 10, the same or equivalent processes as those in FIG.
The fundamental frequency detector 10 detects a fundamental frequency from the bass component signal extracted by the bass component extractor 2 in step ST1, and obtains a frequency n times the frequency (n is an integer and n ≧ 1). It outputs to the gain control part 8 as frequency information (step ST11).
The fundamental frequency detection method of the fundamental frequency detection unit 10 includes a method using an autocorrelation function, a zero cross point detection of a bass component signal, and a peak value detection, but is not limited thereto, and detects a fundamental frequency. Any method may be used.

If there is a change in the detected fundamental frequency (step ST12 “YES”), the gain control unit 8 outputs the frequency information output from the fundamental frequency detection unit 10 and the volume information acquired from the volume information storage unit 7 in step ST7. Are used to calculate a gain value for multiplying the harmonic component signal by the harmonic gain adjustment unit 4 and output the gain value to the harmonic gain adjustment unit 4.
The gain value setting method by the gain control unit 8 may be the method described in the first embodiment or a combination of the methods described in the first and second embodiments. In the first and second embodiments, the lowest resonance frequency f ₀ is used as the reference frequency when the gain control unit 8 calculates the gain value. However, in the fourth embodiment, the fundamental frequency detection unit 10 outputs the gain value. Let frequency information be a reference frequency.

  As described above, according to the fourth embodiment, the audio signal reproduction device detects a fundamental frequency from the bass component signal extracted by the bass component extraction unit 2, and outputs a frequency n times the fundamental frequency as frequency information. The frequency detector 10 includes a gain controller 8 that multiplies the harmonic component signal generated by the harmonic generator 3 according to the set volume of the speaker and the frequency information output by the fundamental frequency detector 10. The value is calculated and output to the harmonic gain adjustment unit 4. Therefore, not only when the set volume is changed, but every time the fundamental frequency of the bass component signal is detected, the gain value to be multiplied by the harmonic component signal is updated, so that the frequency component included in the bass component signal is updated. A certain low-pitched feeling can be obtained without depending.

  In the first to fourth embodiments, the timing at which the gain control unit 8 and the volume control unit 9 calculate and update each gain value is other than the timing shown in FIGS. 2 and 10 (for example, before the step ST1). They may be designed as appropriate.

  In addition, the audio signal reproduction apparatuses according to the first to fourth embodiments include the speaker information storage unit 1, the bass component extraction unit 2, the harmonic generation unit 3, the harmonic gain adjustment unit 4, the adder 5, and the volume gain adjustment unit 6. The volume information storage unit 7, the gain control unit 8, the volume control unit 9, and the fundamental frequency detection unit 10 may each be configured by dedicated hardware. Alternatively, the audio signal reproduction device may be configured by a computer, in which case a program describing the processing contents of the above-described units is stored in the computer memory, and the computer CPU executes the program stored in the memory. To do.

  DESCRIPTION OF SYMBOLS 1 Speaker information storage part, 2 Bass component extraction part, 3 Harmonic generation part, 4 Harmonic gain adjustment part, 5 Adder, 6 Volume gain adjustment part, 7 Volume information storage part, 8 Gain control part, 9 Volume control part 10 Fundamental frequency detector.

Claims (9)

A bass component extraction unit that extracts a bass component signal from the input signal;
A harmonic generation unit that generates a harmonic component signal from the bass component signal extracted by the bass component extraction unit;
A harmonic gain adjustment unit for adjusting the gain of the harmonic component signal generated by the harmonic generation unit;
An adder that adds the harmonic component signal gain-adjusted by the harmonic gain adjustment unit and the input signal to generate an effect-given signal;
A volume gain adjustment unit for adjusting the gain of the effect applying signal generated by the adder;
A gain that multiplies the harmonic component signal generated by the harmonic generation unit according to speaker information that represents the characteristics of the speaker and the set volume of the speaker, and that is output to the harmonic gain adjustment unit A control unit;
An audio signal reproduction apparatus comprising: a volume control unit that calculates a gain value to be multiplied by the effect applying signal generated by the adder according to the set volume and outputs the gain value to the volume gain adjustment unit. The speaker information is the lowest resonance frequency of the speaker,
2. The audio signal reproduction device according to claim 1, wherein the bass component extraction unit extracts a frequency band equal to or lower than the lowest resonance frequency as a bass component signal. The speaker information is table information including the lowest resonance frequencies of a plurality of speakers.
The audio signal reproduction device according to claim 1, wherein the bass component extraction unit extracts a frequency band equal to or lower than the lowest resonance frequency for each speaker as a bass component signal. A fundamental frequency detection unit that detects a fundamental frequency from the bass component signal extracted by the bass component extraction unit and outputs it as frequency information,
The gain control unit calculates a gain value to be multiplied by the harmonic component signal generated by the harmonic generation unit according to the set volume of the speaker and the frequency information output from the fundamental frequency detection unit, and the harmonic gain 4. The audio signal reproduction device according to claim 1, wherein the audio signal reproduction device outputs the signal to an adjustment unit.   The gain control unit uses a predetermined volume as a reference volume, and when the set volume is larger than the reference volume, the set volume is higher than the reference volume so that the gain is smaller than a fluctuation volume from the reference volume to the set volume. When the volume is small, the gain value at the frequency indicated by the speaker information or the frequency information is calculated based on the equal loudness curve of the reference volume and each set volume so that the gain is larger than the fluctuation amount from the reference volume to the set volume. The audio signal reproducing device according to claim 1, wherein the audio signal reproducing device is an audio signal reproducing device.   The gain control unit has a function that approximates the relationship between the fluctuation volume from the reference volume to the set volume and the gain value at the frequency indicated by the speaker information or the frequency information calculated based on the equal loudness curve. 6. The audio signal reproducing apparatus according to claim 5, wherein a gain value is calculated from the audio signal.   7. The audio according to claim 5, wherein, when the calculated gain value exceeds a predetermined threshold value, the gain control unit outputs the threshold value to the harmonic gain adjustment unit instead of the gain value. Signal reproduction device.   8. The audio signal reproduction device according to claim 5, wherein the gain control unit adjusts the calculated gain value according to speaker characteristics.   5. The audio according to claim 4, wherein the fundamental frequency detector detects a fundamental frequency from the bass component signal and outputs a frequency n times the fundamental frequency (n is an integer and n ≧ 1) as frequency information. Signal reproduction device.

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