JP2007067628A - Bass-enhanced reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bass-enhanced reproducing device which enables a listener to more clearly recognize the effect of its performance in a super-low frequency range, and is capable of giving a listener various bass effects. <P>SOLUTION: A low-frequency component is taken out from input signals by an LPF 1, and a super-low frequency component whose frequency is half as high as that of the low-frequency component taken out by the LPF 1 is generated by a low-frequency generating unit 2. A harmonic component contained in the generated super-low frequency component is removed by an LPF 3, and the rest of the generated super-low frequency component is adjusted in gain by a gain controller 4 and then inputted into a mixer 6. The low-frequency component used for generating the super-low frequency component is adjusted in gain by a gain controller 5 and then also inputted into the mixer 6 besides the rest of the generated super-low frequency component, and an additive component that is added to the input signals is outputted from the mixer 6. The additive component and the input signals are summed up by a mixer 11 through the intermediary of delay circuits 7 and 9 both capable of controlling a delay time and gain controllers 8 and 10, so that output signals can be obtained whose low-frequency component is enhanced. Various bass effects can be obtained by controlling mixing ratios in the mixers 6 and 11 and delay times in the delay circuits 7 and 9. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

  The present invention relates to a bass-enhanced reproducing apparatus that emphasizes and reproduces a low-frequency component of an input signal such as an audio signal.

Extracts the low frequency component from the audio signal, divides the extracted low frequency component to generate a signal of half the frequency, adds the generated ultra low frequency signal and the original audio signal, and outputs it A low-frequency emphasis device has been proposed (Patent Documents 1 and 2).
FIG. 2 is a block diagram showing an example of the configuration of the proposed low frequency emphasis reproducing apparatus.
The input signal is passed through a first low-pass filter (LPF) 21, a low-frequency component is extracted, and a rectangular wave is generated from the low-frequency component extracted by the rectangular wave generation processing unit 22. Then, the generated rectangular wave is frequency-divided by the frequency dividing unit 23 to generate a low frequency component having a double period (1/2 frequency). The multiplier 25 multiplies the generated low-frequency component waveform by the envelope generated by the envelope generator 24 from the LPF 21. Since the amplitude of the rectangular wave is fixed, the envelope of the signal that has passed through the LPF 21 of the input stage is multiplied.
Then, the output of the multiplier 25 is passed through the second LPF, the harmonics are removed, and the generated low frequency component is input to the addition processing unit 29 via the level adjustment processing unit 27, and the level adjustment processing unit It adds to the input signal supplied via 28.
As described above, the rectangular wave generated from the low frequency component extracted by the LPF is divided to generate a low frequency component having a double period, and added to the input signal to emphasize the low frequency. .
Japanese Patent Laid-Open No. 4-68699 JP-A-4-302205

In the conventional low-frequency emphasis device described above, only the generated double-frequency low-frequency component is added, so the auditory perception (pitch, etc.) of the effect due to the addition of the low-frequency component is clearly clear. Instead, it could be blurry.
In addition, since the relative delay between the generated ultra-low frequency component and the input signal is not taken into consideration, the sound output from the speaker may cause the ultra-low frequency to be delayed, resulting in a sound that is just a feeling.
Accordingly, an object of the present invention is to provide a low-frequency emphasizing reproduction apparatus that can make a listener more clearly recognize the effect of ultra-low frequencies and obtain various bass effects.

In order to achieve the above object, a bass emphasizing / reproducing apparatus of the present invention includes a low-pass filter that extracts a low-frequency component from an input signal, and a half-frequency of the low-frequency component signal extracted by the low-pass filter. A low-frequency generator that generates a low-frequency signal, a first mixer that adds the low-frequency signal generated by the low-frequency generator, and the low-frequency component signal extracted by the low-pass filter, And a second mixer that adds the output signal of the first mixer and the input signal and outputs the added signal.
A first delay circuit that delays an output signal of the first mixer; and a second delay circuit that delays the input signal, wherein the second mixer includes the first delay circuit. The output of the circuit and the output of the second delay circuit are added.
Furthermore, both the first mixer and the second mixer have a variable mixing ratio.
Furthermore, the delay time of the first delay circuit and the delay time of the second delay circuit can be arbitrarily set.

In general, the lower the frequency, the more difficult it is to recognize the pitch and it is difficult to determine clearly. For example, it is difficult to listen to a low-pitched phrase that is played only with a bass, but it is difficult to get a pitch. Becomes easier.
According to the low-frequency emphasizing reproduction apparatus of the present invention, not only the generated ultra-low frequency component but also the auxiliary low-frequency component (one octave above the generated component) is supplementally mixed. It is possible to make the listener recognize the ultra-low frequency component clearly and effectively. As a result, it is possible to produce an effect of a clear, tight, ultra low frequency range.
In addition, the ultra low frequency component often has a certain delay until it reaches the listener's ear by propagating in the air by driving the speaker or passing through the bass reflex port. This may be perceived as a sense of delay in the bass, or slack.
According to the low-frequency emphasis reproducing apparatus of the present invention, since the delay circuit is provided for both the low-frequency component (additional component) to be mixed with the input signal to be mixed, the additional component is slightly delayed in time from the input signal. The delay until reaching the listener's ear can be absorbed here, and a recognition effect of a sharp deep bass that rises quickly can be obtained. On the other hand, for listeners who like a slightly loose bass sound, the effect can be provided by setting a certain amount of delay in the low-frequency component to be added to the input signal.

FIG. 1 is a block diagram showing a configuration of an embodiment of a low frequency emphasis reproducing apparatus of the present invention.
In this figure, reference numeral 1 denotes a first low-pass filter (LPF) that extracts a low-frequency component from an input signal such as an audio signal. The cut-off frequency fc of the LPF 1 is, for example, fc = 200 Hz, and a low frequency component of 200 Hz or less is extracted from the input signal.
Reference numeral 2 denotes a low-frequency generator that generates a low-frequency signal (ultra-low frequency component) having a frequency half that of the low-frequency component extracted by the LPF 1. Here, as a simple method for generating the ultra low frequency component, a method of dividing a rectangular wave by general zero cross detection, a method of creating a double period by zero cross detection and waveform folding, etc. are used in the time domain. There is a way to do it. In addition, although the processing load becomes high, a pitch detection is performed in the frequency domain by applying FFT (Fast Fourier Transform), and a signal having a frequency ½ of the detected pitch is generated by a VCO or the like. Also good. In this way, an ultra-low frequency component having a period twice (1 octave lower) is generated from the low frequency component extracted by the LPF 1.
Reference numeral 3 denotes a second low-pass filter (LPF) for removing extra harmonics generated when the ultra-low frequency component is generated in the low frequency generator 2, and for example, fc = 100 Hz.
As a result, the super-low frequency component one octave lower generated based on the low frequency component extracted by the first LPF 1 is output from the second LPF 3.

Reference numeral 4 denotes a gain controller that adjusts the gain of the signal of the very low frequency component output from the second LPF 3. Reference numeral 5 denotes a gain controller that receives the output of the first LPF 1 and adjusts its gain. The gain controllers 4 and 5 are configured so that the user can arbitrarily set the gain.
The output of the gain controller 4 and the output of the gain controller 5 are added by a first mixer (mixer) 6.
In this way, a signal (additional component) to be added to the original input signal is output from the first mixer 6. The additional component includes an ultra-low frequency component generated by the low frequency generation unit 2 and a low-frequency component (low frequency component extracted by the first LPF 1) from which the ultra-low frequency component is generated. Both are included. Further, the mixing ratio (mix balance) can be freely changed by adjusting the gains of the gain controllers 4 and 5.
In this way, not only the generated ultra-low frequency component but also the low-frequency component that generated the ultra-low frequency component is added to the input signal, so that the ultra-low frequency component added to the listener is clearly recognized. It becomes possible. Furthermore, various bass effects can be obtained by adjusting the mix balance. For example, when the original low-frequency component is set to “0” and only the generated ultra-low frequency component is set, the atmosphere becomes heavy with only the ultra-low frequency component added. As the original low-frequency component is increased, the pitch recognition becomes easier, and a heavy drive feeling and groove feeling are felt for phrases moving in the low frequency range.

Reference numeral 7 denotes a first delay circuit that delays an additional component output from the first mixer 6 for a predetermined time, and reference numeral 8 denotes a gain controller to which the output of the first delay circuit 7 is input.
Reference numeral 9 denotes a second delay circuit that delays the input signal for a predetermined time, and reference numeral 10 denotes a gain controller to which the output of the second delay circuit 9 is input.
Here, the delay time in the first delay circuit 7 and the second delay circuit 9 can be arbitrarily set by the user. The gains of the gain controllers 8 and 10 can be arbitrarily set by the user.
The additional component signal delayed from the gain controller 8 for a predetermined time and set to a predetermined level and the input signal delayed from the gain controller 10 for a predetermined time and set to a predetermined level are (Mixer) 11 adds and outputs.
As a result, the second mixer 11 outputs a signal in which the low frequency range is added by adding the additional component (low frequency component + super low frequency component) to the input signal.

Here, by adjusting the gains of the gain controllers 8 and 10, the mixing ratio (mix balance) of the input signal and the additional component can be freely adjusted, and the bass enhancement effect can be adjusted.
Further, by adjusting the delay time of the delay circuits 7 and 8, the relative time difference between the input signal and the additional component can be arbitrarily controlled. For example, if the additional component is set to a delay early (about several tens of ms) with respect to the input signal, a deep bass with a tight feeling is produced. On the other hand, if the additional component is set late, it will be a loose deep bass sound.
In this way, by controlling the mix balance in the first mixer 6 and the second mixer 11 and the delay time in the delay circuits 7 and 9, various bass effects can be obtained.

  In the above description, the cut-off frequency fc of the first LPF 1 is 200 Hz, and the cut-off frequency fc of the second LPF 3 is 100 Hz. Can be set to any value.

It is a block diagram which shows the structure of one Embodiment of the bass emphasis reproducing | regenerating apparatus of this invention. It is a block diagram which shows the structural example of the conventional bass emphasis reproducing | regenerating apparatus.

Explanation of symbols

  1: first low-pass filter, 2: low-frequency generator, 3: second low-pass filter, 4, 5: gain controller, 6: first mixer, 7: first delay circuit, 8, 10: Gain controller, 9: second delay circuit, 11: second mixer

Claims (4)

A low-pass filter that extracts low-frequency components from the input signal;
A low-frequency generation unit that generates a low-frequency signal having a frequency half that of the low-frequency component signal extracted by the low-pass filter;
A first mixer that adds the low-frequency signal generated by the low-frequency generation unit and the low-frequency component signal extracted by the low-pass filter;
A bass-enhanced reproduction apparatus comprising: a second mixer that adds and outputs the output signal of the first mixer and the input signal. A first delay circuit for delaying an output signal of the first mixer;
A second delay circuit for delaying the input signal,
2. The bass-enhanced reproducing apparatus according to claim 1, wherein the second mixer adds the output of the first delay circuit and the output of the second delay circuit.   The bass emphasis reproducing apparatus according to claim 1 or 2, wherein a mixing ratio is variable in both the first mixer and the second mixer.   The bass sound according to any one of claims 1 to 3, wherein a delay time of the first delay circuit and a delay time of the second delay circuit can be arbitrarily set. Emphasis playback device.

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