Method and device for spectral expansion for an audio signal

Patent metadata

Field	Value
Publication number	US-10043534-B2
Application number	US-201414578700-A
Country	US
Kind code	B2
Filing date	Dec 22, 2014
Priority date	Dec 23, 2013
Publication date	Aug 7, 2018
Grant date	Aug 7, 2018

Abstract

A method and device for automatically increasing the spectral bandwidth of an audio signal including generating a “mapping” (or “prediction”) matrix based on the analysis of a reference wideband signal and a reference narrowband signal, the mapping matrix being a transformation matrix to predict high frequency energy from a low frequency energy envelope, generating an energy envelope analysis of an input narrowband audio signal, generating a resynthesized noise signal by processing a random noise signal with the mapping matrix and the envelope analysis, high-pass filtering the resynthesized noise signal, and summing the high-pass filtered resynthesized noise signal with the original an input narrowband audio signal. Other embodiments are disclosed.

First claim

What is claimed is:

1. A method for automatically expanding the spectral bandwidth of an audio signal comprising:
generating a mapping matrix based on an analysis of a reference wideband signal and a reference narrowband signal, the mapping matrix being a transformation matrix to predict high frequency energy from a lower frequency energy envelope, where the mapping matrix is generated without using a linear predictive coefficient (LPC) method, wherein the mapping matrix is generated based, in part, on using a dB domain for performing a linear prediction;
generating an energy envelope analysis of an input narrowband audio signal;
generating a resynthesized noise signal by processing a random noise signal with the mapping matrix and the energy envelope analysis;
high-pass filtering the resynthesized noise signal;
generating an output audio signal by summing the high-pass filtered resynthesized noise signal with the input narrowband audio signal; and
generating an audible output from a speaker using the output audio signal.

2. The method of claim 1 , wherein the reference wideband and reference narrowband signals are made from a simultaneous recording of a sentence made with an ambient microphone and an ear canal microphone located in an earphone.

3. The method of claim 1 , where the input narrowband audio signal is taken from an ear-canal microphone located in an earphone.

4. The method of claim 1 , where the input narrowband audio signal is taken from a received speech audio signal in a speech telecommunications system.

5. The method of claim 1 , where the summed signal is directed to a speech telecommunications system.

6. The method of claim 1 , where the summed signal is directed to a voice controlled device.

7. The method of claim 1 , where the mapping matrix is generated from a least squares fit analysis of the reference wideband and reference narrowband signals.

8. The method of claim 1 , where the mapping matrix is generated by a linear regression model, where the input reference wideband signals and reference narrowband signals are first converted to a frequency domain representation, and secondly each frequency band envelope is converted to a dB domain representation.

9. A non-transitory computer readable medium containing instructions for spectral enhancement, the execution of the instructions by a processor of a computer system causing the processor to perform operations comprising:
generating a mapping matrix based on an analysis of a reference wideband signal and a reference narrowband signal, the mapping matrix being a transformation matrix to predict high frequency energy from a lower frequency energy envelope, where the mapping matrix is generated without using a linear predictive coefficient (LPC) method, wherein the mapping matrix is generated based, in part, on using a dB domain for performing a linear prediction;
generating an energy envelope analysis of an input narrowband audio signal;
generating a resynthesized noise signal by processing a random noise signal with the mapping matrix and the energy envelope analysis;
high-pass filtering the resynthesized noise signal;
generating an output audio signal by summing the high-pass filtered resynthesized noise signal with the input narrowband audio signal; and
generating an audible output from a speaker and using the output audio signal.

Assignees

• Personics Holdings Llc
• Staton Techiya Llc

Inventors

• Usher John
• Ellis Dan

Classifications

• G10L21/038 Primary

  using band spreading techniques · CPC title