Method and apparatus for time domain compression and synthesis of unvoiced audible signals
First Claim
1. A method for synthesizing a unit of a time domain information signal substantially lacking periodic characteristics and having a power spectrum substantially invariant over the duration of said unit, said method comprising the steps of:
- storing in memory means a representative small segment of said information signal unit; and
repetitively reproducing at least a portion of said segment a sufficient number of times to reconstruct said information signal unit from said small segment, said reproducing step commencing and terminating with different points in said segment at each repetition thereby to provide a unit substantially free of noticeable periodicity.
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Abstract
Compression and synthesis techniques and related apparatus for time domain signals, particularly signals whose information content resides in the power spectrum such as speech and more particularly signals whose amplitude is aperiodic, such as unvoiced speech sounds. Compression techniques include eliminating serially redundant segments of information. Synthesis, particularly of unvoiced sounds which are sensitive to injected artificial periodicity, involves repeating sequentially portions of the same segmentrepresentative of the source signal, including commencing and terminating at different points each repetition, varying the length of the portion and reproducing the portion forwards and backwards in time. The invention finds application in speech compression and compact speech synthesis devices.
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Citations
12 Claims
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1. A method for synthesizing a unit of a time domain information signal substantially lacking periodic characteristics and having a power spectrum substantially invariant over the duration of said unit, said method comprising the steps of:
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storing in memory means a representative small segment of said information signal unit; and repetitively reproducing at least a portion of said segment a sufficient number of times to reconstruct said information signal unit from said small segment, said reproducing step commencing and terminating with different points in said segment at each repetition thereby to provide a unit substantially free of noticeable periodicity. - View Dependent Claims (2, 3)
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4. A method for synthesizing a unit of a time domain information signal substantially lacking periodic characteristics and having a power spectrum substantially invariant during said time unit of interest wherein said information signal comprises discrete serially-arranged samples in a sequence, said method comprising the steps of storing said samples;
- and iterating repeatedly through said samples commencing and terminating with different samples at each repetition to reconstruct said unit of said information signal from said samples substantially free of noticeable periodicity.
- View Dependent Claims (5, 6)
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7. An apparatus for synthesizing a unit of a time domain information signal substantially lacking periodic characteristics and having a power spectrum substantially invariant during said time unit of interest, said apparatus comprising:
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memory means for storing a representative small segment of said information signal; means coupled to said memory means for generating a reconstructed signal from said information signal segment, said generating means comprising means for repetitively reproducing at least a portion of said signal segment commencing and terminating with different points in said segment at each repetition; and means for limiting said repetitions to a sufficient number of times to reconstruct said unit of said information signal from said small segment. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification