JP2005323156A - Acoustic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize an acoustic control damaging no feeling of power of music centering around a low range while reducing a feeling of strain in a high range from a middle range. <P>SOLUTION: A pulse-width converter 201 is mounted between an amplifier 102 having a clip detecting function and an integrator 103 integrating a clip detecting output and outputting a clip level at a voltage level. The reaction of a limiter 101 is reduced and a sound volume is not much lowered in a low sound component. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an acoustic device that reduces distortion at high volume.

  As shown in FIG. 5, the conventional acoustic apparatus includes an amplifier 102 having a clip detection function, an integrator 103 that integrates the clip detection output and outputs the clip level as a voltage level, and sets the voltage level in advance. A threshold comparator 104 that outputs an output in comparison with a certain threshold, and a limiter 101 that adjusts the output level (volume) of the audio signal from the sound source 105 according to the output from the threshold comparator 104 (for example, , See Patent Document 1).

  In this acoustic apparatus, the output clip is detected by the amplifier 102, a limiter is applied to the audio signal (the audio signal is attenuated), and distortion of the audio output from the speaker 106 at the time of high volume is reduced. .

Japanese Patent Laid-Open No. 03-030506

  However, in a conventional acoustic device, if the limiter is applied by detecting a signal component (clip) exceeding the clip level over the entire audible frequency band, if the music being listened is centered on the bass (low frequency range), There was a problem that the volume was too low and the original power feeling was insufficient.

  The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide an acoustic device and an acoustic control program that can reduce the sense of distortion without impairing the sense of power.

  The acoustic device of the present invention includes a clip detection unit that detects a clip of an audio signal waveform and outputs a signal, a conversion unit that converts the clip detection output signal, a limiter unit that adjusts a volume of the audio signal, And a control unit that restricts the operation of the limiter unit based on the output signal of the conversion unit. With this configuration, the limiter effect can have frequency characteristics.

  In the acoustic device of the present invention, the conversion means is a pulse width converter that converts an output signal width of the clip detection means, and the control unit integrates an output signal of the pulse width converter, and the integration Comparing means for comparing and outputting the output level of the means and a preset level is adopted. With this configuration, it is possible to give a frequency characteristic to the limiter effect by using an amplifier having a general pulse output type clip detection function.

  In the acoustic apparatus of the present invention, the pulse width conversion means is configured to convert a signal width of a frequency lower than a predetermined audio frequency. With this configuration, the effect of the limiter can be reduced in the low frequency range, while the conventional limiter effect can be obtained in the high frequency range.

  Furthermore, the acoustic control program of the present invention is obtained by a clip detection procedure for detecting a clip of an audio signal waveform and outputting a signal to a computer, a conversion procedure for converting the clip detection output signal, and the conversion procedure. And a limiter procedure for adjusting the volume of the audio signal based on the output signal. As a result, acoustic control in consideration of the voice frequency band can be easily realized on software.

  According to the present invention, by providing clip detection means of the audio signal waveform, a converter that changes the clip detection signal according to the audio frequency, and a limiter that adjusts the volume according to the level of the clip detection signal, A frequency characteristic can be given to the limiter effect. Further, by providing the limiter effect with frequency characteristics, it is possible to adjust the excess or deficiency of the sound field in the environment where the acoustic device is placed.

  Hereinafter, an audio device according to an embodiment of the present invention will be described with reference to the drawings. The configuration of the acoustic device according to the embodiment of the present invention is shown in FIG. This audio apparatus includes an amplifier 102 having a clip detection function, an integrator 103 that integrates clip detection outputs and outputs the clip level as a voltage level, and a predetermined voltage level that is set in advance as a threshold value. A threshold value comparator 104 that outputs the result of comparison and a limiter 101 that adjusts the output level of the audio signal from the sound source 105 in accordance with the output from the threshold value comparator 104. Further, a pulse width converter 201 is provided between the amplifier 102 and the integrator 103. In FIG. 1, the same components as those shown in FIG.

  As shown in FIG. 2, the pulse width converter 201 includes a mono multivibrator 301, an inverter 302, and an adder 303. Among these, the mono multivibrator 301 holds a high level signal of the clip pulse signal input from the amplifier 102 in accordance with the time constant set in the mono multivibrator 301.

  Inverter 302 inverts the signal output from mono multivibrator 301. The adder 303 functions to add the clip pulse signal from the amplifier 102 and the inverted signal from the inverter 302 and output the result to the integrator 103.

  The operation of the acoustic apparatus configured as described above will be described with reference to FIG. FIG. 3 is a timing chart of input signals and output signals of the pulse width converter 201 shown in FIG.

  First, the sound signal output from the sound source 105 is adjusted in volume by the limiter 101, amplified by the amplifier 102, further converted into sound by the speaker 106, and emitted. Here, when the signal amplitude from the sound source 105 becomes large and the output waveform becomes a predetermined clip level (positive or negative), the clip detection output in the amplifier 102 becomes low level (L). FIG. 3 is a timing chart showing such output waveforms, clip levels, and clip detection outputs. In response to this clip detection output, the pulse width converter 201 controls the limiter 101.

  That is, the clip detection output from the amplifier 102 is input to the mono multivibrator 301 and the adder 303. In this clip detection output, a high level (H) indicates that there is no clip, and a low level (L) indicates that there is a clip. The clip pulse signal input to the mono multivibrator 301 is maintained at a high level according to a time constant set in advance in the mono multivibrator 301.

  The output signal of the mono multivibrator 301 is inverted via the inverter 302 and input to the adder 303. In the adder 303, the clip detection output from the amplifier 102 and the signal from the inverter 302 are added and output to the integrator 103.

  FIG. 4 is a timing chart showing the relationship between the input and output of the pulse width converter 201. In the low frequency range, the pulse width converter 201 narrows and outputs the clip pulse width according to the time constant set in the mono multivibrator 301. That is, when a clip is detected in the audio signal in the low frequency range, 1/2 of the period T calculated from the input audio frequency is larger than the pulse width tw set in the mono multivibrator 301. In this case, the output (2) of the mono multivibrator 301 includes a low level. This signal is inverted through the inverter 302 (3) and added to the input signal (1) as a high level by the adder 303. That is, the clip pulse is narrowed and output (4).

  On the other hand, in the high range, the clip pulse only passes. When ½ of the period T calculated from the audio frequency is smaller than the pulse width tw set in the mono multivibrator 301, the output (2) of the mono multivibrator 301 is fixed to a high level and added via the inverter 302. One input of the vessel 303 is fixed at a low level (3). Then, the adder output output (4) is the same as the input waveform (1), that is, the pulse width converter 201 only passes the clip pulse.

  Thus, according to the acoustic device according to the embodiment of the present invention, by providing the pulse width converter 201 having the configuration as shown in FIG. Since the clip pulse is only allowed to pass in the high range, the conventional limiter effect can be obtained.

  In addition, although this configuration can obtain separate limiter effects for the low and high frequencies, it does not require a plurality of low and high frequency loops. Therefore, a general digital signal processor (DSP) or the like can be used for a volume controller including a limiter.

  In the above description, an example in which part or all of the pulse width converter 201, the integrator 103, the threshold comparator 104, and the limiter 101 is configured by individual hardware has been described. It is also possible to realize by software using a DSP or the like.

  The acoustic device of the present invention has an effect that a frequency characteristic can be given to the limiter effect, and is useful as a technique for reducing distortion at a large volume.

The block diagram which shows the audio equipment in embodiment of this invention. The block diagram which shows the internal structure of the pulse width converter in embodiment of this invention in FIG. The timing chart which shows the relationship between amplifier output, a clip level, and a clip detection output. The timing chart which shows the input / output signal of a pulse width converter. It is a block diagram which shows the conventional audio equipment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Limiter 102 Amplifier 103 Integrator 104 Threshold comparator 201 Pulse width converter 301 Mono multivibrator 302 Inverter 303 Adder

Claims (4)

  Based on clip detection means for detecting a clip of an audio signal waveform and outputting the signal, conversion means for converting the clip detection output signal, limiter means for adjusting the volume of the audio signal, and an output signal of the conversion means And a control unit that restricts the operation of the limiter means.   The conversion means is a pulse width converter for converting the output signal width of the clip detection means, and the control unit sets in advance the integration means for integrating the output signal of the pulse width converter, and the output level of the integration means. The acoustic apparatus according to claim 1, further comprising a comparison unit that compares the output level with the output level.   The acoustic apparatus according to claim 2, wherein the pulse width conversion means converts a signal width of a frequency lower than a predetermined audio frequency.   A clip detection procedure for detecting a clip of an audio signal waveform and outputting a signal to a computer, a conversion procedure for converting the clip detection output signal, and a volume of the audio signal based on the output signal obtained by the conversion procedure A sound control program for executing a limiter procedure for adjusting the sound.

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