Method and System for Masking Speech
First Claim
1. A method of producing a substantially unintelligible, obfuscated speech signal from intelligible speech, comprising the steps of:
- obtaining a speech signal representing a speech stream;
temporally partitioning said speech signal into a plurality of segments, said segments occurring in an initial order within said speech signal;
selecting a plurality of selected segments from among said segments; and
assembling said selected segments, in an order different than said initial order, to produce said obfuscated speech signal;
wherein said segments represent phonemes within said speech stream;
wherein said temporally partitioning step comprises the steps of;
squaring said speech signal;
calculating a short time average of said speech signal over a short time scale;
calculating a medium time average of said speech signal over a medium time scale;
calculating a difference between said short time average and said medium time average; and
detecting zero crossings in said difference;
wherein said zero crossings delineate said segments.
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Accused Products
Abstract
A simple and efficient method for producing an obfuscated speech signal which may be used to mask a stream of speech, is disclosed. A speech signal representing the speech stream to be masked is obtained. The speech signal is then temporally partitioned into segments, preferably corresponding to phonemes within the speech stream. The segments are then stored in a memory, and some or all of the segments are subsequently selected, retrieved, and assembled into an obfuscated speech signal representing an unintelligible speech stream that, when combined with the speech signal or reproduced and combined with the speech stream, provides a masking effect. While the presently preferred embodiment finds application most readily in an open plan office, embodiments suitable for use in restaurants, classrooms, and in telecommunications systems are also disclosed.
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Citations
14 Claims
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1. A method of producing a substantially unintelligible, obfuscated speech signal from intelligible speech, comprising the steps of:
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obtaining a speech signal representing a speech stream;
temporally partitioning said speech signal into a plurality of segments, said segments occurring in an initial order within said speech signal;
selecting a plurality of selected segments from among said segments; and
assembling said selected segments, in an order different than said initial order, to produce said obfuscated speech signal;
wherein said segments represent phonemes within said speech stream;
wherein said temporally partitioning step comprises the steps of;
squaring said speech signal;
calculating a short time average of said speech signal over a short time scale;
calculating a medium time average of said speech signal over a medium time scale;
calculating a difference between said short time average and said medium time average; and
detecting zero crossings in said difference;
wherein said zero crossings delineate said segments. - View Dependent Claims (2, 3)
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4. A method of producing a substantially unintelligible, obfuscated speech signal from intelligible speech, comprising the steps of:
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obtaining a speech signal representing a speech stream;
temporally partitioning said speech signal into a plurality of segments, said segments occurring in an initial order within said speech signal;
selecting a plurality of selected segments from among said segments; and
assembling said selected segments, in an order different than said initial order, to produce said obfuscated speech signal;
further comprising the step, immediately following said temporally partitioning step, of;
storing said segments in a memory; and
further comprising the step, immediately following said selecting step, of;
retrieving said selected segments from said memory;
wherein said storing step comprises the steps of;
squaring said speech signal;
calculating a long time average of said speech signal over a long time scale;
determining when said long time average is above a first threshold and when said long time average is below a second threshold;
halting said storing of said segments in said memory when said long time average is below said second threshold; and
resuming said storing of said segments in said memory when said long time average is above said first threshold. - View Dependent Claims (5)
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6. A method of producing a substantially unintelligible, obfuscated speech signal from intelligible speech, comprising the steps of:
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obtaining a speech signal representing a speech stream;
temporally partitioning said speech signal into a plurality of segments, said segments occurring in an initial order within said speech signal;
selecting a plurality of selected segments from among said segments; and
assembling said selected segments, in an order different than said initial order, to produce said obfuscated speech signal;
further comprising the step, immediately following said temporally partitioning step, of;
storing said segments in a memory; and
further comprising the step, immediately following said selecting step, of;
retrieving said selected segments from said memory;
wherein said retrieving step comprises the steps of;
squaring said speech signal;
calculating a long time average of said speech signal over a long time scale;
determining when said long time average is above a first threshold and when said long time average is below a second threshold;
halting said retrieving of said segments from said memory when said long time average is below said second threshold; and
resuming said retrieving of said segments from said memory when said long time average is above said first threshold. - View Dependent Claims (7)
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8. An apparatus for producing a substantially unintelligible, obfuscated speech signal from intelligible speech, comprising:
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a module for obtaining a speech signal representing a speech stream;
a module for temporally partitioning said speech signal into a plurality of segments, said segments occurring in an initial order within said speech signal;
a module for selecting a plurality of selected segments from among said segments; and
a module for assembling said selected segments, in an order different than said initial order, to produce said obfuscated speech signal;
wherein said module for temporally partitioning further comprises;
a module for squaring said speech signal;
a module for calculating a short time average of said speech signal over a short time scale;
a module for calculating a medium time average of said speech signal over a medium time scale;
a module for calculating a difference between said short time average and said medium time average; and
a module for detecting zero crossings in said difference;
wherein said zero crossings delineate said segments. - View Dependent Claims (9, 10)
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11. An apparatus for producing a substantially unintelligible, obfuscated speech signal from intelligible speech, comprising:
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a module for obtaining a speech signal representing a speech stream;
a module for temporally partitioning said speech signal into a plurality of segments, said segments occurring in an initial order within said speech signal;
a module for selecting a plurality of selected segments from among said segments;
a module for assembling said selected segments, in an order different than said initial order, to produce said obfuscated speech signal;
a memory for storing said segments; and
a module for retrieving said selected segments from said memory;
wherein said memory comprises;
a module for squaring said speech signal;
a module for calculating a long time average of said speech signal over a long time scale;
a module for determining when said long time average is above a first threshold and when said long time average is below a second threshold;
a module for halting said storing of said segments in said memory when said long time average is below said second threshold; and
a module for resuming said storing of said segments in said memory when said long time average is above said first threshold. - View Dependent Claims (12)
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13. An apparatus for producing a substantially unintelligible, obfuscated speech signal from intelligible speech, comprising:
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a module for obtaining a speech signal representing a speech stream;
a module for temporally partitioning said speech signal into a plurality of segments, said segments occurring in an initial order within said speech signal;
a module for selecting a plurality of selected segments from among said segments;
a module for assembling said selected segments, in an order different than said initial order, to produce said obfuscated speech signal;
a memory for storing said segments; and
a module for retrieving said selected segments from said memory;
wherein said module for retrieving comprises;
a module for squaring said speech signal;
a module for calculating a long time average of said speech signal over a long time scale;
a module for determining when said long time average is above a first threshold and when said long time average is below a second threshold;
a module for halting said retrieving of said segments from said memory when said long time average is below said second threshold; and
a module for resuming said retrieving of said segments from said memory when said long time average is above said first threshold. - View Dependent Claims (14)
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Specification