JP2006093767A - Amplifier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an amplifier capable of correcting a frequency characteristic of a received audio signal so that a sound field with a surround effect can be reproduced, while keeping the features of the frequency characteristics for the received audio signal, without adjusting a frequency band of the received audio signal into predetermined frequency characteristics by automatic acoustic characteristic adjusting function. <P>SOLUTION: The amplifier includes an adjustment section for adjusting the frequency characteristics of the audio signal outputted from a speaker into a predetermined frequency characteristics; a filter section for correcting the frequency characteristics of the audio signal; an analysis section for analyzing the frequency characteristics of the audio signal; a storage section for storing the analyzed frequency characteristics; a weighting processing section for applying weighting to the frequency characteristics stored in the storage section; a calculation section for calculating the average frequency characteristics of the frequency characteristics that have been subjected to weighting; and a coefficient setting section for setting the filter coefficient of the filter section, on the basis of the predetermined frequency characteristics and the average frequency characteristics. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an amplifying apparatus capable of amplifying and outputting an audio signal and adjusting an acoustic characteristic of an audio signal output from a connected speaker.

  As a recording medium on which a multi-channel audio signal is recorded, there is a DVD (Digital Versatile Disc). The multi-channel audio signal read from the DVD by the playback device is input to an amplification device (for example, an AV (Audio Visual) amplifier). This amplifying device converts an input multi-channel audio signal into an audio signal for each channel, amplifies the converted audio signal, and outputs the amplified audio signal to a plurality of speakers. The multi-channel audio signal output from the amplifying apparatus can reproduce a sound field having a surround effect by being output from a plurality of speakers.

  In order to reproduce a sound field having a surround effect, it is necessary to set values of various parameters related to acoustic characteristics such as sound pressure level and frequency characteristics of an audio signal output from each speaker to appropriate values in an amplifier. There is. Generally, the user manually sets the values of these parameters, but there is an amplifying apparatus having an automatic acoustic characteristic adjustment function capable of automatically setting the values of these parameters.

  Amplifying devices with automatic acoustic characteristic adjustment function output test signals from each speaker, collect the test signals output from each speaker by a microphone installed at the listening position and connected to the amplifying device. Measure the frequency characteristics, sound pressure level, etc. of the test signal. The amplifying apparatus adjusts the measured frequency characteristics, sound pressure level, and the like so as to coincide with the frequency characteristics, sound pressure level, and the like set in advance in the amplifying apparatus (see, for example, Patent Document 1).

  An amplifying apparatus having an automatic acoustic characteristic adjustment function as disclosed in Patent Document 1 uses, for example, white noise or pink noise as a test signal, and the frequency characteristics of the test signal output from the speaker are, for example, all frequencies. Adjust the frequency characteristics of the band to be flat.

JP 2002-354599 A

  Some audio signals recorded on a recording medium have their frequency characteristics intentionally corrected in the process of producing the audio signal. For example, there is an audio signal that has been corrected to emphasize the high frequency band of the audio signal or corrected to emphasize the frequency band of the vocal sound. When such a corrected audio signal is input to an amplifying apparatus having an automatic acoustic characteristic adjusting function, the amplifying apparatus has a frequency characteristic of the entire frequency band even for an audio signal whose frequency characteristic is intentionally corrected. Adjustment is made so as to obtain a predetermined frequency characteristic. For this reason, an amplification device having a conventional automatic acoustic characteristic adjustment function reproduces a sound field having a surround effect when, for example, an audio signal in which the frequency band of a vocal sound is emphasized is adjusted to a predetermined frequency characteristic. However, since the frequency band of the vocal sound is attenuated, a problem arises that it becomes difficult for the listener to hear the vocal sound.

  In addition, an amplifying apparatus having an automatic acoustic characteristic adjustment function is an audio signal in a frequency band where the signal level is low (for example, a frequency band where the signal level is extremely low and close to the noise level, or a frequency band where there is no signal component of the audio signal). Is input so that the frequency components of these frequency bands are also adjusted to have a predetermined frequency characteristic, so that only the noise level is amplified in these frequency bands. For this reason, the conventional amplification device having the automatic acoustic characteristic adjustment function can reproduce a sound field having a surround effect, but the amplified noise is output from the speaker together with the audio signal. This causes a problem of deterioration.

  The present invention has been made to solve the above-described problem, and the input audio signal is not adjusted to a predetermined frequency characteristic by the automatic acoustic characteristic adjustment function. It is an object of the present invention to provide an amplifying apparatus capable of correcting the frequency characteristics of an input audio signal so that a sound field having a surround effect can be reproduced while maintaining the characteristics of the frequency characteristics.

  In order to solve the above-described problem, the invention according to claim 1 of the present application is an amplification device including an input unit that inputs an audio signal and an amplification unit that amplifies the audio signal input from the input unit. An adjustment unit that adjusts the frequency characteristics of audio signals output from a plurality of speakers connected to the amplifying apparatus to a predetermined frequency characteristic, and the frequency characteristics of the audio signals input from the input unit according to a filter coefficient A filter unit that corrects and outputs to the amplification unit, an analysis unit that analyzes a frequency characteristic of an audio signal input from the input unit, a storage unit that stores a plurality of frequency characteristics analyzed by the analysis unit, and the storage A weighting processing unit for weighting a plurality of frequency characteristics stored in the unit, and a plurality of frequency characteristics weighted by the weighting processing unit. A calculation unit that calculates a frequency characteristic; and a coefficient setting unit that sets a filter coefficient of the filter unit from a predetermined frequency characteristic adjusted by the adjustment unit and an average frequency characteristic calculated by the calculation unit. It is characterized by.

  In addition, in the invention according to claim 2 of the present application, in the amplification device according to claim 1, the coefficient setting unit has a frequency characteristic of a frequency band in which a signal level of an audio signal is equal to or higher than a predetermined level as the filter unit. Is characterized in that the filter coefficient is set so as to correct.

  According to a third aspect of the present invention, in the amplification device according to the first or second aspect, an audio signal output from the input unit to the filter unit until the coefficient setting unit sets a filter coefficient. A delay unit for delaying is provided.

  According to the amplifying device of the present invention, the frequency band of the input audio signal is not adjusted to the predetermined frequency characteristic by the automatic acoustic characteristic adjustment function, while maintaining the characteristics of the frequency characteristic of the input audio signal, It is possible to provide an amplifying apparatus that corrects the frequency characteristics of an input audio signal so that a sound field having a surround effect can be reproduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of an amplifying apparatus according to an embodiment of the present invention. In FIG. 1, 1 is an audio signal input unit, 2 is a signal processing unit, 3 is an audio signal output unit, 4 is an operation unit, 5 is a control unit, 6 is a test signal generation unit, 7 is a test signal input unit, and 8 is Indicates a microphone. The amplifying apparatus of the present embodiment includes an automatic acoustic characteristic adjustment function that automatically sets various parameter values relating to acoustic characteristics such as sound pressure level and frequency characteristics of audio signals output from each speaker to appropriate values. Yes.

  An audio signal input unit 1 shown in FIG. 1 inputs a multi-channel digital audio signal output from a playback device such as a DVD player. The signal processing unit 2 decodes the digital audio signal input from the audio signal input unit 1, performs signal processing such as adjustment of frequency characteristics and addition of a sound field effect, and separates the digital audio signal for each channel. When the input digital audio signal is a 5.1 channel digital audio signal, the signal processing unit 2 converts the 5.1 channel digital audio signal into an FL (Front Left) channel, an FR (Front Right) channel, and a C channel. (Center) channel, SL (Surround Left) channel, SR (Surround Right) channel and SW (Sub Woofer) channel digital audio signals are separated.

  When the signal processing unit 2 performs automatic adjustment of the acoustic characteristics of the audio signal, when the test signal collected by the microphone 8 is input from the test signal input unit 7, the audio output from each speaker Measure acoustic characteristics such as sound pressure level and frequency characteristics of the signal. The signal processing unit 2 adjusts the values of various parameters related to acoustic characteristics to appropriate values according to the measurement results.

  The audio signal output unit 3 converts the digital audio signal of each channel output from the signal processing unit 2 into an analog audio signal, amplifies it, and outputs it to a plurality of speakers (not shown) connected to the audio signal output unit 3. The operation unit 4 includes a selection button for selecting the automatic acoustic characteristic adjustment function, a start button for starting the operation of the automatic acoustic characteristic adjustment function, and an operation button for inputting or changing each parameter of the acoustic characteristic. The control unit 5 controls the entire amplifying apparatus of this embodiment. When the automatic acoustic characteristic adjustment function is selected by the selection button of the operation unit 4 and the start button is pressed, the control unit 5 controls the test signal generation unit 6 to generate a test signal. The control unit 5 performs control so that the test signal generated by the test signal generation unit 6 is output from the audio signal output unit 3 through the signal processing unit 2 in a predetermined channel order.

  The test signal generator 6 generates a test signal used for measuring values of various parameters related to the acoustic characteristics during automatic adjustment of the acoustic characteristics. The test signal generated by the test signal generator 6 is output from a plurality of speakers via the signal processor 2 and the audio signal output unit 3. This test signal is white noise, pink noise, or the like.

  The test signal input unit 7 is connected to the microphone 8. The microphone 8 collects the test signal output from the speaker and inputs it to the test signal input unit 7. The test signal input unit 7 converts the input test signal from an analog signal to a digital signal, amplifies it, and inputs it to the signal processing unit 2.

  FIG. 2 is a block diagram illustrating a configuration of the signal processing unit 2. In FIG. 2, 21 is an analysis unit, 22 is a storage unit, 23 is a weighting processing unit, 24 is a calculation unit, 25 is a coefficient setting unit, 26 is a filter unit, 27 is a delay unit, and 28 is an adjustment unit.

First, the automatic acoustic characteristic adjustment function provided in the amplifying apparatus of the present embodiment will be described.
The test signal output from the speaker is collected by the microphone 8. The collected test signal is input to the adjustment unit 28 of the signal processing unit 2 via the test signal input unit 7. The adjustment unit 28 shown in FIG. 2 measures the acoustic characteristics such as the sound pressure level and the frequency characteristic of the test signal of each channel output from each speaker using the input test signal, and according to the measurement result. Adjust the values of various parameters related to acoustic characteristics to appropriate values. The adjustment unit 28 adjusts the frequency characteristic so that the measured frequency characteristic of the test signal of each channel becomes a flat frequency characteristic in the entire frequency band. Data indicating the adjusted frequency characteristics (hereinafter referred to as adjustment data) is input to the coefficient setting unit 25 and stored in a memory (not shown).

Next, in the amplifying apparatus of the present embodiment, description will be given of correcting the frequency characteristics of the digital audio signal input by the signal processing unit 2.
The analysis unit 21 shown in FIG. 2 analyzes the frequency characteristics of the entire frequency band of the digital audio signal every time a predetermined number of sample data of the digital audio signal input from the audio signal input unit 1 is input. For example, the analysis unit 21 analyzes the frequency characteristics of a digital audio signal having a predetermined number of sample data by FFT (Fast Fourier Transform). Data indicating frequency characteristics of a digital audio signal having a predetermined number of sample data analyzed by the analysis unit 21 (hereinafter referred to as frequency characteristic data) is input to the coefficient setting unit 25. The analyzed frequency characteristic data is stored in the storage unit 22. The storage unit 22 stores, for example, a plurality of frequency characteristic data analyzed from a digital audio signal input during a few seconds.

  The weighting processing unit 23 performs processing for weighting a plurality of frequency characteristic data read from the storage unit 22. For example, the weighting processing unit 23 minimizes the ratio of applying the weighting to the frequency characteristic data analyzed from the digital audio signal input several seconds before the present in the plurality of frequency characteristic data stored in the storage unit 22, A process of gradually increasing the weighting ratio for the frequency characteristic data analyzed after the frequency characteristic data is performed to maximize the ratio of weighting the currently analyzed frequency characteristic data.

  The calculating unit 24 calculates average frequency characteristic data (hereinafter referred to as average frequency characteristic data) from the frequency characteristic data weighted by the weighting processing unit 23. The calculated average frequency characteristic data is input to the coefficient setting unit 25. As described above, in the plurality of frequency characteristic data stored in the storage unit 22 by the weighting processing unit 23, the weighting ratio applied to the frequency characteristic data analyzed from the digital audio signal input several seconds before the present is the smallest. Since the weighting ratio applied to the analyzed frequency characteristic data is maximized, the average frequency characteristic data calculated by the calculation unit 24 is close to the frequency characteristic of the digital audio signal currently input. It becomes frequency characteristic data. The average frequency characteristic data is calculated by the calculation unit 24 every time the analysis unit 21 analyzes the frequency characteristic data.

  The coefficient setting unit 25 sets the filter coefficient of the filter unit 27 from the average frequency characteristic data calculated by the calculation unit 24 and the adjustment data input from the adjustment unit 28 and stored in the memory. FIG. 3 is a diagram for explaining the setting of the filter coefficient of the filter unit 26 by the coefficient setting unit 25. The frequency characteristic shown in FIG. 3A is the frequency characteristic indicated by the adjustment data input from the adjustment unit 28. The frequency characteristic shown in FIG. 3B is the frequency characteristic indicated by the average frequency characteristic data input from the calculation unit 24.

  The coefficient setting unit 25 adds the average frequency characteristic data input from the calculation unit 24 and the adjustment data stored in the memory. The frequency characteristic shown in FIG. 3C indicates a frequency characteristic obtained by the coefficient setting unit 25 adding the frequency characteristic shown in FIG. 3A and the average frequency characteristic shown in FIG. The coefficient setting unit 25 sets the filter coefficient of the filter unit 26 so that the frequency characteristic corrected by the filter unit 26 becomes the frequency characteristic shown in FIG. The coefficient setting unit 25 sets the filter coefficient of the filter unit 26 from the average frequency characteristic data and the adjustment data every time the average frequency characteristic data is input from the calculation unit 24.

  The frequency characteristic shown in FIG. 3C for setting the filter coefficient of the filter unit 26 is based on the average frequency characteristic data calculated by the coefficient setting unit 25 by the calculation unit 24 and the frequency characteristic data adjusted by the adjustment unit 28. It is what I have sought. Here, the average frequency characteristic data calculated by the calculation unit 24 is frequency characteristic data close to the frequency characteristic data of the currently input digital audio signal. Further, the frequency characteristic data adjusted by the adjusting unit 28 is frequency characteristic data adjusted so that the frequency characteristic of the audio signal output from the speaker becomes a flat frequency characteristic. Therefore, the frequency characteristic shown in FIG. 3C has the frequency characteristic of the digital audio signal that is currently input, and the frequency characteristic that brings the frequency characteristic of the audio signal output from the speaker close to flat. Therefore, the audio signal output from the speaker is an audio signal that can reproduce a sound field having a surround effect while maintaining the characteristics of the frequency characteristics of the digital audio signal input to the amplifying apparatus of the present embodiment. Become.

  The filter unit 26 corrects the frequency characteristics of the digital audio signal input from the delay unit 27 with the filter coefficient set by the coefficient setting unit 25. The filter unit 26 is a parametric equalizer including a plurality of digital filters, for example. The digital audio signal whose frequency characteristic is corrected by the filter unit 26 is input to the audio signal output unit 3. The delay unit 27 delays the digital audio signal input to the filter unit 26 until the coefficient setting unit 25 sets the filter coefficient of the filter unit 26.

Another embodiment for setting the filter coefficient of the filter unit 26 by the coefficient setting unit 25 will be described.
As described above, the frequency characteristic data analyzed by the analysis unit 21 is input to the coefficient setting unit 25. When the input digital audio signal has a frequency band with a low signal level (for example, a frequency band close to a noise level or a frequency band without a signal component of the audio signal), the coefficient setting unit 25 filters this frequency band. The filter coefficient is set so that the unit 26 does not correct it. For this reason, the coefficient setting unit 25 sets the filter coefficient so as to correct the frequency characteristics in a frequency band in which the signal level of the input digital audio signal is equal to or higher than a predetermined level (for example, −80 dB).

  The amplifying apparatus according to the present embodiment corrects the frequency characteristic data adjusted to a predetermined frequency characteristic by the adjustment unit 28 according to the frequency characteristic data analyzed from the audio signal input by the analysis unit 21 and is corrected. The filter coefficient corresponding to the frequency characteristic data is set in the filter unit 26. For this reason, in the prior art, the input audio signal is always adjusted to a predetermined frequency characteristic. However, in the amplifying apparatus of this embodiment, an automatic acoustic characteristic is selected according to the frequency characteristic of the input audio signal. The predetermined frequency characteristic adjusted by the adjustment function can be corrected. Therefore, even if an audio signal in which the high frequency band is emphasized or an audio signal in which the vocal frequency band is emphasized is input, a sound field having a surround effect can be reproduced with these frequency bands emphasized. Audio signals that can be output can be output.

  Further, the amplifying apparatus of the present embodiment has a frequency band with a low signal level in the input audio signal (for example, a frequency band with an extremely low signal level and a noise level or a frequency band without the signal component of the audio signal). In some cases, the filter coefficient is set so that the filter unit 27 does not correct this frequency band. In the prior art, since the input audio signal is always adjusted to a predetermined frequency characteristic, if the input audio signal has a frequency band in which the signal level of the audio signal component is low or absent, only the noise level is amplified. . However, since the amplification device of the present embodiment does not correct the frequency characteristics of the frequency band where the signal level of the audio signal component is low or absent, amplification of the noise level of this frequency band can be avoided, and a sound field having a surround effect can be avoided. An audio signal that can reproduce the above can be output.

The block diagram which shows the structure of the amplifier which is an Example of this invention. The block diagram which shows the structure of a signal processing part. The figure explaining the setting of the filter coefficient of the filter part by the coefficient setting part 26. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Audio signal input part, 2 ... Signal processing part, 3 ... Audio signal output part, 4 ... Operation part, 5 ... Control part, 6 ... Test signal generation part, 7 ... Test signal input part, 8 ... Microphone, 21 ... Analysis unit, 22 ... storage unit, 23 ... weighting processing unit, 24 ... calculation unit, 25 ... coefficient setting unit, 26 ... filter unit, 27 ... delay unit, 28 ... adjustment unit

Claims (3)

In an amplifying apparatus comprising an input unit for inputting an audio signal and an amplifying unit for amplifying the audio signal input from the input unit,
An adjustment unit that adjusts the frequency characteristics of audio signals output from a plurality of speakers connected to the amplification device to predetermined frequency characteristics;
A filter unit that corrects a frequency characteristic of an audio signal input from the input unit according to a filter coefficient and outputs the corrected signal to the amplifying unit;
An analysis unit for analyzing a frequency characteristic of an audio signal input from the input unit;
A storage unit for storing a plurality of frequency characteristics analyzed by the analysis unit;
A weighting processing unit for weighting a plurality of frequency characteristics stored in the storage unit;
A calculation unit for calculating an average frequency characteristic of a plurality of frequency characteristics weighted by the weighting processing unit;
An amplifying apparatus comprising: a coefficient setting unit that sets a filter coefficient of the filter unit from a predetermined frequency characteristic adjusted by the adjustment unit and an average frequency characteristic calculated by the calculation unit. The amplification device according to claim 1,
The amplification apparatus, wherein the coefficient setting unit sets a filter coefficient so that the filter unit corrects a frequency characteristic of a frequency band in which a signal level of an audio signal is equal to or higher than a predetermined level. In the amplification device according to claim 1 or 2,
An amplifying apparatus comprising: a delay unit that delays an audio signal output from the input unit to the filter unit until the coefficient setting unit sets a filter coefficient.

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