Peak detection when adapting a signal gain based on signal loudness

Patent metadata

Field	Value
Publication number	US-9219455-B2
Application number	US-201313757304-A
Country	US
Kind code	B2
Filing date	Feb 1, 2013
Priority date	Feb 1, 2012
Publication date	Dec 22, 2015
Grant date	Dec 22, 2015

Abstract

Various embodiments relate to a system for adapting a signal gain, which comprises a peak detector configured to receive an audio input signal containing consecutive signal blocks and to dynamically establish a current input signal level of the audio input signal, and a loudness determination unit configured to dynamically determine a perceived loudness of a current signal block of the audio input signal based on a psycho-acoustic model of a human hearing. Furthermore the system comprises a time constant generation unit configured to determine a time constant based on the perceived loudness of the current signal block and the perceived loudness of a preceding signal block, wherein the time constant describing a change of the signal gain. A gain determination unit is configured to determine the signal gain for the current signal block based on the time constant and the current input signal level.

First claim

What is claimed is:

1. A method of adapting a signal gain, the method comprising:
receiving an audio input signal containing consecutive signal blocks;
establishing a current input signal level of the audio input signal;
determining a perceived loudness of a current signal block of the audio input signal based on a psycho-acoustic model of a human hearing using a signal level range of the current signal block of the audio input signal;
determining the signal gain for the current signal block based on a time constant and based on the current input signal level, the time constant describing a change of the signal gain from a signal block to another signal block, wherein the time constant is determined based on the perceived loudness of the current signal block and the perceived loudness of a preceding signal block; and
amplifying the audio input signal with the determined signal gain to obtain an audio output signal.

2. The method according to claim 1 , wherein the signal gain is determined such that an output signal level of the audio output signal is always smaller than a predefined threshold.

3. The method according to claim 1 , further comprising determining the time constants.

4. The method according to claim 3 , wherein a rising time constant is used to obtain an increased signal gain between two consecutive signal blocks of the audio output signal and a falling time constant is used to obtain a decreased signal gain between two consecutive signal blocks of the audio output signal.

5. The method according to claim 4 , wherein the signal gain is determined in such a way that an average output signal level of the audio output signal averaged over a number of signal blocks equals a predefined value.

6. The method according to claim 4 , wherein the signal gain is determined in such a way that an average loudness of the audio output signal averaged over a number of signal blocks equals a predefined value.

7. The method according to claim 1 , wherein the time constants are determined in such a way that a falling time constant allows a larger maximum absolute signal gain change between consecutive signal blocks than a rising time constant.

8. The method according to claim 3 , further comprising establishing an estimated output signal level of the audio output signal based on the current input signal level and the signal gain.

9. The method according to claim 8 , wherein the maximum absolute signal gain change allowable by rising or falling time constants is increased if the estimated output signal level is above a predefined threshold.

10. The method according to claim 3 , further comprising including a delay time into the audio input signal before it is output, wherein the delay time relates to the time needed to determine the signal gain.

11. The method according to claim 10 , wherein each signal block contains a predefined number of digital samples.

12. The method according to claim 3 , wherein the perceived loudness is determined further based on signal statistics of the audio input signal.

13. A system for adapting a signal gain, comprising:
a peak detector configured to receive an audio input signal containing consecutive signal blocks, and to dynamically establish a current input signal level of the audio input signal;
a loudness determination unit configured to dynamically determine a perceived loudness of a current signal block of the audio input signal based on a psycho-acoustic model of a human hearing using a signal level range of the current signal block of the audio input signal;
a time constant generation unit configured to determine a time constant based on the perceived loudness of the current signal block and the perceived loudness of a preceding signal block, the time constant describing a change of the signal gain from a signal block to another signal block;
a gain determination unit, configured to determine the signal gain for the current signal block based on the time constant and based on the current input signal level; and
a gain unit, configured to amplify the audio input signal using the signal gain to obtain an audio output signal.

Assignees

• Harman Becker Automotive Sys

Inventors

• Hess Wolfgang
• Baehren Frank

Classifications

• H03G3/00 Primary

  Gain control in amplifiers or frequency changers · CPC title

• H03G5/005

  of digital signals · CPC title

• H03G9/005

  of digital or coded signals · CPC title

• H03G3/3089 Primary

  Control of digital or coded signals · CPC title

• H03G9/025

  frequency-dependent volume compression or expansion, e.g. multiple-band systems (H03G9/10, H03G9/18 take precedence) · CPC title