SPEECH SIGNAL PROCESSING RESPONSIVE TO LOW NOISE LEVELS
A method of speech recognition in a vehicle. Audio including noise and a speech signal representative of an utterance from a user is received via a microphone, and a signal-to-noise ratio (SNR) for the received audio is calculated using a processor. It is determined whether the calculated SNR is greater than a predetermined SNR. If so, then a noise distribution is identified for addition to the received audio, and noise corresponding to the identified noise distribution is injected into the received audio to produce noise-injected audio including the speech signal.
1 . A method of speech recognition in a vehicle, the method comprising the steps of:
(a) receiving, via a microphone, audio including noise and a speech signal representative of an utterance from a user;
(b) calculating, via a processor, a signal-to-noise ratio (SNR) for the received audio;
(c) determining whether the calculated SNR is greater than a predetermined SNR and, if so, then;
(d) identifying a noise distribution for addition to the received audio; and
(e) injecting into the received audio, noise corresponding to the identified noise distribution to produce noise-injected audio including the speech signal.
2 . The method of claim 1 , further comprising the step of:
(f) pre-processing the noise-injected audio to generate acoustic feature vectors.
3 . The method of claim 2 , further comprising the step of:
(g) decoding the generated acoustic feature vectors to produce hypotheses for the user utterance in the speech signal.
4 . The method of claim 3 , further comprising the step of:
(h) post-processing the hypotheses to identify the utterance.
5 . The method of claim 1 , wherein the identified noise distribution corresponds to the vehicle category of the vehicle.
6 . The method of claim 5 , wherein the identified noise distribution corresponds to the make and model of the vehicle.
7 . The method of claim 1 , wherein the predetermined SNR is vehicle-specific.
8 . The method of claim 7 , wherein the vehicle-specific predetermined SNR is based on a correlation of SNR and speech recognition performance in the vehicle during development of an ASR system for the vehicle.
9 . The method of claim 8 , wherein the identified noise distribution corresponds to the correlation of SNR and speech recognition performance.
10 . A computer program product embodied in a computer readable medium and including instructions usable by a computer processor of a speech processing system to cause the system to implement steps of a method according to claim 1 .
11 . A method of speech recognition in a vehicle, the method comprising the steps of:
(a) receiving, via a microphone, audio including noise and a speech signal representative of an utterance from a user;
(b) calculating, via a processor, a signal-to-noise ratio (SNR) for the received audio;
(c) determining whether the calculated SNR is greater than a vehicle-specific predetermined SNR and, if so, then;
(d) identifying a vehicle-specific noise distribution for addition to the received audio;
(e) injecting into the received audio, noise corresponding to the identified noise distribution to produce noise-injected audio including the speech signal;
(f) pre-processing the noise-injected audio to generate acoustic feature vectors;
(g) decoding the generated acoustic feature vectors to produce hypotheses for the user utterance in the speech signal; and
(h) post-processing the hypotheses to identify the utterance.
12 . The method of claim 11 , wherein the vehicle-specific predetermined SNR is based on a correlation of SNR and speech recognition performance in the vehicle during development of an ASR system for the vehicle.
13 . The method of claim 12 , wherein the identified noise distribution corresponds to the correlation of SNR and speech recognition performance.
14 . The method of claim 11 , wherein the identified noise distribution includes at least one of a uniform, normal, or gaussian distribution.
15 . A computer program product embodied in a computer readable medium and including instructions usable by a computer processor of a speech processing system to cause the system to implement steps of a method according to claim 11 .