Acoustic device and method of reproducing acoustic signal

Patent metadata

Field	Value
Publication number	US-9294059-B2
Application number	US-201113695360-A
Country	US
Kind code	B2
Filing date	Apr 19, 2011
Priority date	Apr 27, 2010
Publication date	Mar 22, 2016
Grant date	Mar 22, 2016

Abstract

An acoustic device, which reproduces an acoustic signal of one acoustic source selected from a plurality of acoustic sources. A first averaging unit averages signal levels of the acoustic signal for a first time period to obtain a first average signal. A second averaging unit averages the signal levels for a second time period shorter than the first time period to obtain a second average signal. A selecting unit selects either the first average signal or the second average signal as one signal having a signal level higher than the other. A gain decreasing unit decreases a gain of the acoustic signal according to the signal level of the one signal if the signal level of the one signal is higher than a threshold value determined according to the one acoustic source. A correcting unit corrects the signal levels of the acoustic signal according to the gain.

First claim

The invention claimed is:

1. An acoustic device configured to reproduce an acoustic signal of one acoustic source which is selected from a plurality of acoustic sources, the acoustic device comprising:
a first averaging unit configured to average signal levels of the acoustic signal for a first calculation time period;
a second averaging unit configured to average the signal levels of the acoustic signal for a second calculation time period which is shorter than the first calculation time period;
a selecting unit configured to select one signal from among signals output from the first averaging unit and the second averaging unit, the one signal having a signal level higher than the other;
a determining unit configured to determine whether the signal level of the selected one signal is higher than a threshold value which is determined according to the one acoustic source;
a gain decreasing unit configured to decrease a gain of the acoustic signal according to the signal level of the one signal, in a case where the signal level of the selected one signal is higher than the threshold value;
a correcting unit configured to correct a signal level of the acoustic signal according to the gain; and
a threshold value updating unit configured to update the threshold value so as to be the same value as the signal level of the selected one signal, in a case where the signal level of the selected one signal is higher than the threshold value.

2. The acoustic device according to claim 1 , wherein the threshold value updating unit updates the threshold value so as to be the same value as a peak signal level of the selected one signal.

3. The acoustic device according to claim 1 , further comprising:
a switching unit configured to switch the acoustic source from among the plurality of acoustic sources, according to an operation of a user; and
a threshold value setting unit configured to set, in response to switching of the acoustic source, an initial value of the threshold value according to the acoustic source after the switching, based on a signal level of a signal which is selected by the selecting unit after the switching.

4. The acoustic device according to claim 1 , wherein the threshold value is initialized at a switching timing from the one acoustic source to another acoustic source.

5. A method of controlling a gain for reproducing an acoustic signal of one acoustic source which is selected from a plurality of acoustic sources, the method comprising:
(a) averaging signal levels of the acoustic signal for a first calculation time period;
(b) averaging the signal levels of the acoustic signal for a second calculation time period which is shorter than the first calculation time period;
(c) selecting one signal from among signals output from the step (a) and the step (b), the one signal having a signal level higher than the other;
(d) determining whether the signal level of the selected one signal is higher than a threshold value which is determined according to the one acoustic signal;
(e) decreasing a gain of the acoustic signal according to the signal level of the one signal, in a case where the signal level of the selected one signal is higher than the threshold value;
(f) correcting a signal level of the acoustic signal according to the gain; and
updating the threshold value so as to be the same value as the signal level of the selected one signal, in a case where the signal level of the selected one signal is higher than the threshold value.

6. The acoustic device according to claim 5 , wherein the threshold value is initialized at a switching timing from the one acoustic source to another acoustic source.

Assignees

• Kubo Masahiko
• Tomita Yuji
• Maeda Masanobu
• Akai Nahoko
• Fujitsu Ten Ltd

Inventors

• Kubo Masahiko
• Tomita Yuji
• Maeda Masanobu
• Akai Nahoko

Classifications

• H03G3/20 Primary

  Automatic control ({H03G3/005 takes precedence;} combined with volume compression or expansion H03G7/00) · CPC title

• H03G5/165

  Equalizers; Volume or gain control in limited frequency bands · CPC title

• H04R2430/01

  Aspects of volume control, not necessarily automatic, in sound systems · CPC title

• H04R2499/13

  Acoustic transducers and sound field adaptation in vehicles · CPC title

• H04R27/00

  Public address systems (circuits for preventing acoustic reaction H04R3/02; circuits for distributing signals to loudspeakers H04R3/12; {monitoring or testing arrangements for public address systems H04R29/007}; amplifiers H03F) · CPC title