Audio signal noise reduction device and method

• US 20070150261A1
• Filed: 11/27/2006
• Published: 06/28/2007
• Est. Priority Date: 11/28/2005
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Ozawa, Kazuhiko
• Granted Patent: US 7,711,557 B2
• Time in Patent Office: Days
• US Class Current: 704/200.100
• CPC Class Codes: G10L 21/01 Correction of time axis
• CPC Class Codes: G10L 21/0208 Noise filtering
• CPC Class Codes: G10L 21/0232 Processing in the frequency domain
• CPC Class Codes: G10L 21/0264 characterised by the type of parameter measurement, e.g. correlation techniques, zero crossing techniques or predictive techniques

Abstract

An audio signal noise reduction device that includes: input means for making an input of one or more audio signals; timing generation means for generating a gap period in accordance with a generation period of noise coming from a noise generation source included in the audio signal; noise removal means for removing the noise from the audio signal; level envelope detection means for continuously detecting a level envelope of the audio signal; coefficient generation means for generating a coefficient for the level envelope in the gap period in accordance with a signal level provided by the level envelope detection means; interpolation signal generation means; level modulation means for subjecting a signal from the interpolation signal generation means to level modulation using the coefficient generated by the coefficient generation means; mixing means for mixing an output from the noise removal means and an output from the level modulation means; and selection means for outputting a signal from the mixing means in a period corresponding to the gap period, and outputting the audio signal not in the gap period.

Claims

1. An audio signal noise reduction device, comprising:

input means for making an input of one or more audio signals;

timing generation means for generating a gap period in accordance with a generation period of noise coming from a noise generation source included in the audio signal;

noise removal means for removing the noise from the audio signal;

level envelope detection means for continuously detecting a level envelope of the audio signal;

coefficient generation means for generating a coefficient for the level envelope in the gap period in accordance with a signal level provided by the level envelope detection means;

interpolation signal generation means;

level modulation means for subjecting a signal from the interpolation signal generation means to level modulation using the coefficient generated by the coefficient generation means;

mixing means for mixing an output from the noise removal means and an output from the level modulation means; and

selection means for outputting a signal from the mixing means in a period corresponding to the gap period, and not in the gap period, outputting the audio signal.

3. The audio signal noise reduction device according to claim 1 or 2, wherein

the audio signal is captured by a microphone.

4. The audio signal noise reduction device according to claim 1 or 2, wherein

the timing generation means sets, as the noise generation period, a period in which a noise detection signal derived by a sensor is of a predetermined level or more.

5. The audio signal noise reduction device according to claim 1 or 2, wherein

the timing generation means generates the gap period from the noise generation period based on a drive signal that drives the noise generation source.

6. The audio signal noise reduction device according to claim 1 or 2, wherein

the noise removal means is configured by a filter that removes a noise band.

7. The audio signal noise reduction device according to claim 6, wherein

the interpolation signal generation means generates a signal by filtering, via the filter whose pass band is a reject band of the noise removal means, a single or plurality of periodic signals of a predetermined waveform and a predetermined cycle, a random signal being uniform in level over a voice band, or a signal being a mixture of the periodic signal and the random signal at a predetermined ratio.

8. The audio signal noise reduction device according to claim 1 or 2, wherein

the selection means performs cross-fading.

2. An audio signal noise reduction device, comprising:

input means for making an input of one or more audio signals;

timing generation means for generating a gap period in accordance with a generation period of noise coming from a noise generation source included in the audio signal;

noise removal means for removing the noise from the audio signal;

level envelope detection means for continuously detecting a level envelope of the audio signal;

masking amount determination means for determining, in accordance with a signal level provided by the level envelope detection means, a masking level for a human sense of hearing in the gap period;

interpolation signal generation means;

level modulation means for subjecting a signal from the interpolation signal generation means to level modulation using a coefficient generated by the masking amount determination means;

mixing means for mixing an output from the noise removal means and an output from the level modulation means; and

selection means for outputting a signal from the mixing means in a period corresponding to the gap period, and not in the gap period, outputting the audio signal.

9. An audio signal noise reduction device, comprising:

input means for making an input of one or more audio signals;

timing generation means for generating a gap period in accordance with a generation period of noise coming from a noise generation source included in the audio signal;

noise removal means for removing the noise from the audio signal;

level envelope detection means for continuously detecting a level envelope of the audio signal;

first coefficient generation means for generating, in accordance with a signal level provided by the level envelope detection means, a level coefficient for the level envelope in the gap period;

spectrum envelope detection means for continuously detecting a frequency spectrum of the audio signal;

second coefficient generation means for generating a spectrum coefficient in the gap period in accordance with spectrum information provided by the spectrum envelope detection means;

interpolation signal generation means;

level modulation means for subjecting a signal from the interpolation signal generation means to level modulation using the coefficient generated by the first coefficient generation means;

mixing means for mixing an output from the noise removal means and an output from the interpolation signal generation means via the level modulation means and variable filter means that performs frequency modulation using the coefficient generated by the second coefficient generation means; and

selection means for outputting a signal from the mixing means in a period corresponding to the gap period, and not in the gap period, outputting the audio signal.

10. An audio signal noise reduction method, comprising the steps of:

generating a gap period in accordance with a generation period of noise coming from a noise generation source included in one or more incoming audio signals;

detecting continuously a level envelope of the audio signal;

generating a coefficient for the level envelope in accordance with a signal level being a detection result;

generating an interpolation signal, and subjecting the interpolation signal to level modulation using the coefficient;

mixing an output being a result of the level modulation and an output being a result of removing the noise from the audio signal; and

outputting a signal being a mixing result in a period corresponding to the gap period, and not in the gap period, outputting the audio signal as it is.

11. An audio signal noise reduction method, comprising the steps of:

generating a gap period in accordance with a generation period of noise coming from a noise generation source included in one or more incoming audio signals;

detecting continuously a level envelope of the audio signal;

determining, using a signal level being a detection result, a masking level for a human sense of hearing in the gap period;

generating an interpolation signal, and subjecting the interpolation signal to level modulation using a coefficient generated by the masking level determination;

mixing an output being a result of the level modulation and an output being a result of removing the noise from the audio signal; and

outputting a signal being a mixing result in a period corresponding to the gap period, and not in the gap period, outputting the audio signal as it is.

12. An audio signal noise reduction method, comprising the steps of:

generating a gap period in accordance with a generation period of noise coming from a noise generation source included in one or more incoming audio signals;

detecting continuously a level envelope of the audio signal;

generating a level coefficient for the level envelope in accordance with a signal level being a detection result;

detecting continuously a frequency spectrum of the audio signal;

generating a spectrum coefficient in the gap period in accordance with spectrum information being a detection result;

generating an interpolation signal, and subjecting the interpolation signal to level modulation using the level coefficient and to frequency modulation using the spectrum coefficient;

mixing an output being a result of the level modulation and an output being a result of removing the noise from the audio signal; and

outputting a signal being a mixing result in a period corresponding to the gap period, and not in the gap period, outputting the audio signal as it is.