Apparatus and methods for speech analysis
First Claim
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1. Apparatus for speech analysis comprising:
- an analogue to digital converter connected to receive a speech signal to be analyzed,filter means coupled to an output of said analogue to digital converter, for filtering said output to provide a plurality of signals, representative of power intensities in a plurality of frequency ranges in the audio frequency band,median-filtering means, coupled to said filter means, for repeatedly processing a group of successive samples in each said frequency range by multiplying the samples in each said group by respective coefficients and summing the resultants, andsmoothing means for repeatedly processing a group of successive outputs of the median-filtering means in said each frequency range by selecting one output according to relative magnitudes thereof.
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Abstract
Input signals representative of speech are unreliable as inputs for speech recognition if processed conventionally by, among other processes, filtering into separate frequency bands. Further processing according to the invention takes the output from a filter bank and after operations of rectification and integration provides a process of median filtering and smoothing which significantly reduces the sampling rate of the filtered signals while retaining the important acoustic features of the input speech.
22 Citations
8 Claims
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1. Apparatus for speech analysis comprising:
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an analogue to digital converter connected to receive a speech signal to be analyzed, filter means coupled to an output of said analogue to digital converter, for filtering said output to provide a plurality of signals, representative of power intensities in a plurality of frequency ranges in the audio frequency band, median-filtering means, coupled to said filter means, for repeatedly processing a group of successive samples in each said frequency range by multiplying the samples in each said group by respective coefficients and summing the resultants, and smoothing means for repeatedly processing a group of successive outputs of the median-filtering means in said each frequency range by selecting one output according to relative magnitudes thereof. - View Dependent Claims (2, 3, 4, 6, 7)
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5. A method of spectrum analysis comprising the steps of
converting an analogue signal, having a spectrum to be investigated, to digital form, filtering the digital signal to provide signals representative of power intensities in a plurality of frequency ranges in said spectrum, repeatedly processing a group of successive samples in each said frequency range by multiplying the samples in each group by a respective coefficient and summing the resultants, and repeatedly processing a group of successive summed resultants in each range by selecting one output according to relative magnitudes.
Specification
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Current AssigneeBritish Technology Group Ltd.
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Original AssigneeNational Research Development Corporation
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InventorsHolmes, John N.
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Primary Examiner(s)Wong, Peter S.
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Assistant Examiner(s)VOELTZ, EMANUEL T
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Application NumberUS06/927,721Time in Patent Office844 DaysField of Search381/31-33, 381/41-50, 381/29-30, 381/36-40, 381/51, 364/513.5, 364/724, 333/165-167, 370/70, 370/123, 375/26, 375/34US Class Current704/220CPC Class CodesG10L 19/02 using spectral analysis, e....
