MAPPING OBSTRUENT SPEECH ENERGY TO LOWER FREQUENCIES

1 . A method of processing a speech signal, comprising the steps of:

(a) receiving an utterance from a user via a microphone that converts the utterance into a speech signal; and

(b) pre-processing the speech signal using a processor, including:

extracting acoustic data from the received speech signal;

determining from the acoustic data whether the utterance includes one or more obstruents;

estimating speech energy from higher frequencies associated with identified obstruents; and

mapping the estimated speech energy to lower frequencies.

2 . The method of claim 1 , wherein the determining step includes using a pattern classifier.

3 . The method of claim 1 , wherein the mapping step includes using an adaptive digital filter.

4 . The method of claim 1 , further comprising the step of (c) decoding the mapped speech energy to produce a plurality of hypotheses for the received utterance in an attempt to recognize the utterance.

5 . The method of claim 1 , further comprising the step of (c) transmitting the mapped speech energy to another user.

6 . A method of processing a speech signal, comprising the steps of:

(a) receiving an utterance from a user via a microphone that converts the utterance into a speech signal; and

(b) pre-processing the speech signal using a processor, including:

extracting acoustic data from the received speech signal;

using a subword pattern classifier to determine from the acoustic data whether the utterance includes one or more obstruents;

estimating speech energy from higher frequencies associated with identified obstruents; and

using an adaptive digital filter to map the estimated speech energy to lower frequencies.

7 . The method of claim 6 , further comprising the step of (c) decoding the mapped speech energy to produce a plurality of hypotheses for the received utterance in an attempt to recognize the utterance.

8 . The method of claim 6 , further comprising the step of (c) transmitting the mapped speech energy to another user.

9 . A computer program product including instructions on a computer readable medium and executable by a computer processor of a speech recognition system to cause the system to implement steps comprising:

(a) receiving an utterance from a user via a microphone that converts the utterance into a speech signal; and

(b) pre-processing the speech signal using a processor, including:

extracting acoustic data from the received speech signal;

determining from the acoustic data whether the utterance includes one or more obstruents;

estimating speech energy from higher frequencies associated with identified obstruents; and

mapping the estimated speech energy to lower frequencies.