JP2000270392A - Sound quality adjustment device - Google Patents

Abstract

(57) Abstract: An object of the present invention is to provide a sound quality adjustment device capable of adjusting sound quality matching human hearing characteristics by using an equalizer constituted by a critical band. SOLUTION: A band noise and a sine wave having a frequency bandwidth input by an input means 7 are generated by a noise generation means 3 and a sine wave generation means 4 by a control means 5. The listener listens to the loudness of the two sounds and finds a frequency band in which the band noise sounds larger. This frequency band becomes the critical bandwidth, which is set by the critical bandwidth setting means 8 in the equalizer 2 for sound quality adjustment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound quality adjusting device capable of adjusting sound quality matched to human hearing characteristics.

[0002]

2. Description of the Related Art A conventional sound quality adjusting device will be described with reference to FIG.

In FIG. 5, reference numeral 51 denotes a CD player;
Is an equalizer for adjusting sound quality, 53 is an amplifier, and 54 is a speaker.

An audio signal reproduced by a CD player 51 is input to an equalizer 52 for adjusting sound quality. In the equalizer, the gain of each frequency band of the audio signal is controlled, and the audio signal is reproduced from the speaker 54 through the amplifier 53.

[0005] Here, the frequency band controlled by the equalizer is generally one octave interval such as 125, 250, 500, 1K, 2KHz or a finer 1/3 octave interval. The equalizer includes digital equalizers (IIR filters and FIR filters) and analog equalizers.

The listener can realize his / her favorite sound quality by adjusting the gain of each frequency band as shown in FIG. 6, for example.

[0007]

By the way, human hearing has a plurality of band-pass filters called critical bands, and it is said that sound is integrated and heard within this critical band (auditory and psychoacoustic, corona). Company). Therefore, in an equalizer configured with a bandwidth smaller than the critical bandwidth, even if adjacent bands are controlled, there is almost no change in sound quality. That is, the hardware configuration is overspec. Conversely, in an equalizer configured with a bandwidth wider than the critical bandwidth, a plurality of critical bands are controlled at the same time, making it difficult to finely adjust sound quality.

Therefore, in an equalizer configured with a bandwidth different from the critical bandwidth of humans, there is a problem in that it is impossible to adjust the sound quality to match the sense of hearing, or it is overspecified in hardware, making adjustment difficult. Was.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a sound quality adjusting device which can measure a critical bandwidth of an individual and adjust the sound quality in accordance with the audibility by using an equalizer constituted by the bandwidth.

[0010]

In order to solve the above-mentioned problems, an invention according to claim 1 of the present application provides an equalizer divided into a plurality of frequency bands for adjusting the sound quality of an input audio signal, and a band noise. , A critical bandwidth measuring means for measuring a critical bandwidth of a listener, an input means for inputting a frequency bandwidth of band noise generated by the critical bandwidth measuring means, and a measurement by the critical bandwidth measuring means. And a critical bandwidth setting means for setting the critical bandwidth to the equalizer.

[0011] The invention of claim 3 of the present application is an equalizer divided into a plurality of frequency bands for adjusting the sound quality of an input audio signal, signal level detection means for detecting the level of each critical band of the audio signal, A microphone that collects background noise at the listening location, and a noise level detection unit that detects a level of each of the critical bands of the collected background noise,
Comparing means for comparing the level of each critical band detected by the signal level detecting means and the background noise level detecting means; an equalizer controlling means for controlling characteristics of the equalizer based on a comparison result of the comparing means; Critical bandwidth measuring means for generating noise to measure the critical bandwidth of the listener, input means for inputting the frequency bandwidth of the band noise generated by the critical bandwidth measuring means, and the critical bandwidth measuring means The apparatus further comprises a critical bandwidth setting means for setting the measured critical bandwidth to the equalizer, the signal level detecting means, and the background noise level detecting means.

The inventions of claims 2 and 4 of the present application are claims 1 and 3
Wherein the critical bandwidth measuring means includes a noise generating means for generating band noise for measuring a critical bandwidth, a sine wave generating means for generating a sine wave, and a frequency bandwidth input by the input means. Control means for controlling the noise generating means so as to generate band noise and controlling the sine wave generating means so as to generate a sine wave of a center frequency of the frequency bandwidth, and the band noise and the sine wave Is provided.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

(Embodiment 1) FIG. 1 is a configuration diagram of a first embodiment. In FIG. 1, 1 is an audio signal input means for inputting an audio signal, 2 is an equalizer divided into a plurality of frequency bands for adjusting the sound quality of the input audio signal, and 3 is a band noise for measuring a critical band. A noise generating means for generating a sine wave; a sine wave generating means for generating a sine wave; and a control means for controlling the noise generating means so as to generate a band noise having a frequency bandwidth inputted by the input means. Control means for controlling the sine wave generating means so as to generate a sine wave having the center frequency of, and measuring a critical bandwidth; 6, a switch for switching between band noise and a sine wave; Input means 8 for inputting the frequency bandwidth of the band noise to be adjusted, and a threshold for setting the critical bandwidth measured by the control means 5 to the equalizer 2. Frequency width setting means,
9 is a switch for switching between the audio signal and the signal from the critical bandwidth measuring means 12, 10 is an amplifier, 11 is a speaker, and 12 is a critical bandwidth measuring means. The critical bandwidth measuring means 12 includes a noise generating means 3, a sine wave generating means 4, a control means 5, and a switch 6.

First, the listener sets the switch 9 to b to generate a test signal for measuring the critical bandwidth. When the frequency bandwidth f is input by the input means 7, the control means 5 controls the noise generation means 3 to reproduce the band noise of the same bandwidth. At the same time, a sine wave corresponding to the center frequency of the band noise is generated from the sine wave generation means 4.

First, a method of measuring the critical bandwidth when the lowest frequency is f1 will be described. Assuming that the lowest frequency is f1 and the frequency bandwidth is .f, band noise from f1 to f1 + .f is generated from the noise generating means 3. And at the same time,
A sine wave having a frequency f0 represented by the equation (1) is generated from the sine wave generating means 4. This f0 corresponds to the center frequency of the band noise.

F0 = 10 (log (f1) + log (f1 + Δf)) / 2 (1) FIG. 2 shows a band noise having a minimum frequency f1 and a frequency bandwidth Δf, and a band noise having a frequency f0. FIG. 4 is a frequency characteristic diagram showing a relationship with a sine wave. Reference numeral 21 denotes band noise when the frequency band is narrow, 22 denotes an intermediate case, and 23 denotes a wide case.
24 is a sine wave. The three types of band noise and the sine wave are controlled by the control means 5 so that they are always reproduced at the same sound pressure level. In this case, the sound pressure level is
Therefore, it is preferable to use a speaker having relatively flat characteristics. Further, in order to eliminate the influence of the sound pressure frequency characteristics, it is preferable that the inverse characteristics of the sound pressure frequency characteristics of the speaker 11 be convolved with band noise or a sine wave by signal processing in advance. Furthermore, since headphones have relatively flat sound pressure frequency characteristics, the effects of sound pressure frequency characteristics and background noise can be reduced by using headphones instead of speakers.

Switching between the noise a and the sine wave b by the switch 6 and comparing the band noise with the loudness of the sine wave,
When the frequency band of the band noise is narrow, the band noise and the sine wave sound almost the same size, but when the frequency band is wider than a certain frequency bandwidth, the band noise sounds larger. The frequency bandwidth at this time is the critical bandwidth. For example, in FIG. 2, in the case of 21 and 22, the band noise and the sine wave have the same sound volume, but in the case of 23, the band noise sounds louder.

The listener compares and determines the loudness of the sound with respect to the frequency band inputted by the input means 7 while switching the band noise and the sine wave by the switch 6. If the loudness is the same, the frequency band is expanded by the input means 7,
Compare the loudness again. Then, the critical bandwidth is measured while gradually increasing the frequency of the sine wave to a frequency bandwidth at which the loudness of the band noise increases.

The frequency bandwidth input by the input means 7 starts from a narrow bandwidth, for example, 10 Hz, and is set at intervals of 10 Hz or 20 Hz.
Hz, 30 Hz, etc.
If the input means 7 is set in advance by a method of expanding the ratio of 3 times or 0.4 times equally, the operation becomes simple for the listener. This method can be realized in the form of a rotary volume or a slide volume with divided contacts, a changeover switch, a plurality of buttons for increasing or decreasing the bandwidth, and the like.

Further, a method in which the listener directly inputs a numerical value of an arbitrary frequency bandwidth may be used. In this case, the operation becomes complicated, but an accurate measurement of the critical bandwidth can be performed. This method can be realized in the form of a rotary volume or a slide volume of a continuous contact, a numeric key used on a computer keyboard, or a display for displaying a numerical value.

With the above operation, if the critical bandwidth when the lowest frequency is f1 is Δf1, then the lowest frequency is f1
The same operation is performed for the case of + Δf1 to measure the critical bandwidth. Then, this operation is repeated from a low band to a high band (for example, an audible frequency band from 20 Hz to 20 KHz), and a critical bandwidth at each lowest frequency is measured.

FIG. 3 shows a critical bandwidth for a hearing person.
(Zwicker "Psychoacoustics", Nishimura Shoten) However, it is thought that the critical bandwidth increases and the frequency resolution decreases in the elderly. Strictly speaking, it is considered that the critical bandwidth is slightly different for each individual even for a hearing person. Therefore, the critical bandwidth needs to be measured and set for each individual.

The critical bandwidth measured by the above operation is set to the equalizer 2 by the critical bandwidth setting means 8. When the switch 9 is set to a, the audio signal input by the audio signal input means 1 is adjusted in sound quality by the equalizer 2 and reproduced from the speaker 11 through the amplifier 10. The listener can freely control the equalizer 2 configured with the critical bandwidth to achieve desired sound quality.

As described above, by measuring the critical bandwidth of each individual and setting it in the equalizer, it is possible to adjust the sound quality that matches the hearing characteristics. Also, when measuring the critical bandwidth, if the frequency bandwidth of the band noise is increased, the sound volume does not suddenly increase from a certain frequency bandwidth but gradually increases, so if the boundary is difficult to understand There is. As in the present case, by comparing the sine wave as a reference with the sine wave as needed, the judgment of the listener can be made easier, and the critical band can be measured accurately.

The equalizer 2 can be realized by analog processing and digital processing in the same manner as a conventional graphic equalizer.

Although the switching between the band noise and the sine wave has been described as being performed by the listener himself, the switching may be performed automatically at certain time intervals.

(Embodiment 2) FIG. 4 is a configuration diagram of a second embodiment. In the first embodiment, good listening is realized regardless of background noise by measuring surrounding environmental noise and background noise and adjusting sound quality according to the situation.

In FIG. 4, reference numeral 41 denotes a microphone for picking up background noise, reference numeral 42 denotes a background noise level detecting means for measuring a sound pressure level of each background noise in each critical band, and reference numeral 43 denotes a sound of each audio signal in each critical band. Input signal level detecting means for measuring the pressure level; 44, a comparing means for comparing the sound pressure level between the background noise level and the input signal level; 45, an equalizer controlling means for controlling the equalizer 2 based on the comparison result of the comparing means. is there.

According to the procedure described in the first embodiment, the critical bandwidth of the listener is measured in advance. Then, the result is set in the equalizer 2, the background noise level detecting means 42, and the input signal level detecting means 43 by the critical bandwidth setting means 8.

The background noise input by the microphone 41 is
The sound pressure level is input to the background noise level detecting means 42 and detected for each critical band. On the other hand, the audio signal input by the audio signal input means 1 is input to the input signal level detection means 43, and the amplification factor of the amplifier 10, the sound pressure frequency characteristic of the speaker 11, and the distance from the speaker 11 to the listening position are also determined. At this time, the sound pressure level in each critical band at the listening position is detected. This level detection is performed at certain time intervals. Normally, detection is performed in units of tens to hundreds of milliseconds, but if background noise and the level fluctuation of the input signal are severe, it is necessary to perform level detection at shorter time intervals, and if there is almost no level fluctuation, Longer time intervals are fine. Then, the level detection results of the background noise level detecting means 42 and the input signal level detecting means 43 are compared with the comparing means 4.
4 is compared. Here, for example, the level difference between the background noise and the input signal is calculated for each critical band. If the input signal level in a certain critical band is lower than the background noise level, the input signal in that band is masked by the background noise, so that the sound quality of the input signal changes or the sound cannot be heard.

Therefore, the equalizer control means 45 controls the equalizer 2 to amplify the input signal level in the target critical band, thereby reducing the influence of masking due to background noise. The amount of amplification needs to be at least the level difference between the background noise and the input signal or more.
For example, when the background noise level is 60 dB and the input signal level is 55 dB, the amplification amount needs to be at least 5 dB or more. The audio signal whose sound quality has been adjusted by the equalizer 2 is passed through an amplifier 10 to a speaker 11.
Will be played back.

As described above, by automatically controlling the equalizer 2 having a critical bandwidth based on the background noise level picked up by the microphone 41 and adjusting the sound quality of the input signal, the background noise Eliminates the effect of masking, and can always listen with good sound quality.

The microphone 41 is preferably installed near the position of the listener.

The sound pressure frequency characteristics and the listening distance of the speaker 11 used for obtaining the sound pressure level of the input signal at the listening position are stored in the input signal detecting means 43 in advance, or the data is directly stored. You can enter it.

[0036]

According to the first aspect of the present invention, by measuring the critical bandwidth of an individual and setting it to an equalizer for adjusting the sound quality, it is possible to adjust the sound quality that matches the hearing characteristics.

According to the second and fourth aspects of the present invention, when measuring the critical bandwidth, the listener can make a judgment by comparing the loudness of the reference sine wave with the loudness of the signal for measurement. This facilitates accurate measurement of critical bandwidth.

According to the third aspect of the present invention, the sound quality of the input signal is adjusted by automatically controlling the equalizer having the critical bandwidth based on the background noise level picked up by the microphone. The effect of masking due to background noise is eliminated, and the input signal can always be heard with good sound quality.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a sound quality adjustment device according to a first embodiment of the present invention.

FIG. 2 is a frequency characteristic diagram of band noise and a sine wave.

FIG. 3 is a diagram illustrating an example of a critical bandwidth.

FIG. 4 is a configuration diagram of a sound quality adjustment device according to a second embodiment of the present invention.

FIG. 5 is a configuration diagram of a conventional sound quality adjustment device.

FIG. 6 is an external view of a conventional sound quality adjusting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Audio signal input means 2 Equalizer 3 Noise generating means 4 Sine wave generating means 5 Control means 6 Switching device 7 Input means 8 Critical bandwidth setting means 9 Switching device 10 Amplifier 11 Speaker 12 Critical bandwidth measuring means 41 Microphone 42 Dark noise level Detecting means 43 input signal level detecting means 44 comparing means 45 equalizer controlling means

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Satoru Ibaraki 1006 Kazuma Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. (72) Inventor Junichi Tagawa 1006 Odaka Kazuma Kadoma, Osaka Pref. Terms (reference) 5D020 CE01 5J030 AA01 AB05 AC01 AC09 AC11 AC16 AC18 AC19 AC22 AC25

Claims (4)

[Claims] 1. An equalizer divided into a plurality of frequency bands for adjusting the sound quality of an input audio signal, a critical bandwidth measuring means for generating band noise and measuring a critical bandwidth of a listener, Input means for inputting the frequency bandwidth of the band noise generated by the bandwidth measuring means, and critical bandwidth setting means for setting the critical bandwidth measured by the critical bandwidth measuring means to the equalizer. Sound quality adjustment device. 2. The critical bandwidth measuring means includes: a noise generating means for generating a band noise for measuring a critical bandwidth; a sine wave generating means for generating a sine wave; and a frequency input by the input means. Control means for controlling the noise generating means so as to generate a band noise of a bandwidth and controlling the sine wave generating means so as to generate a sine wave having a center frequency of the frequency bandwidth; and 2. The sound quality adjusting device according to claim 1, further comprising a switch for selecting a sine wave. 3. An equalizer divided into a plurality of frequency bands for adjusting the sound quality of an input audio signal, signal level detecting means for detecting a level of each critical band of the audio signal, and a background noise at a listening place. A microphone for picking up sound, a noise level detecting means for detecting a level of each critical band of the collected background noise, and a level for each critical band detected by the signal level detecting means and the background noise level detecting means. Comparison means for comparing, the equalizer control means for controlling the characteristics of the equalizer based on the comparison result of the comparison means, and a critical bandwidth measurement means for generating a band noise to measure the critical bandwidth of the listener, Input means for inputting the frequency bandwidth of the band noise generated by the critical bandwidth measuring means, and inputting the critical bandwidth measured by the critical bandwidth measuring means to the equal A sound quality adjusting device comprising a riser, a signal level detecting means, and a critical bandwidth setting means for setting the background noise level detecting means. 4. The critical bandwidth measuring means includes a noise generating means for generating band noise for measuring a critical bandwidth, a sine wave generating means for generating a sine wave, and a frequency input by the input means. Control means for controlling the noise generating means so as to generate a band noise of a bandwidth and controlling the sine wave generating means so as to generate a sine wave having a center frequency of the frequency bandwidth; and 4. The sound quality adjusting device according to claim 3, further comprising a switch for selecting a sine wave.