Circuit for determining that an audio signal is either speech or non-speech
First Claim
1. A circuit for distinguishing between speech and non-speech signals for judging an input audio signal to be a non-speech signal when a level of the input audio signal is lower than a predetermined level and judging the input audio signal to be a speech signal when the level of the input audio signal is higher than the predetermined level, comprising:
- a comparator for comparing the level of the input audio signal with the predetermined level; and
level changing control means for raising or lowering the predetermined level by a predetermined amount in accordance wit a ratio of a total non-speech time duration of the input audio signal to a time period having a value equal to a predetermined constant.
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Abstract
A threshold level for determining whether an input audio signal is a speech or non-speech signal in a voice operated recorder is changed in accordance with the ratio of the non-speech duration of the input audio signal to a predetermined period of time so as to decrease the influence of ambient noise on the judgement between speech and non-speech signals as made by the voice operated recorder.
31 Citations
11 Claims
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1. A circuit for distinguishing between speech and non-speech signals for judging an input audio signal to be a non-speech signal when a level of the input audio signal is lower than a predetermined level and judging the input audio signal to be a speech signal when the level of the input audio signal is higher than the predetermined level, comprising:
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a comparator for comparing the level of the input audio signal with the predetermined level; and level changing control means for raising or lowering the predetermined level by a predetermined amount in accordance wit a ratio of a total non-speech time duration of the input audio signal to a time period having a value equal to a predetermined constant. - View Dependent Claims (2, 3, 4)
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5. A circuit for distinguishing between speech and non-speech signals for judging an input audio signal to be a non-speech signal when a level of the input audio signal is lower than a predetermined level and judging the input audio signal to be a speech signal when the level of the input audio signal is higher than the predetermined level, comprising:
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a comparator for comparing the level of the input audio signal with the predetermined level; and level changing control means for raising or lowering the predetermined judging level by a predetermined amount in accordance with a ratio of a non-speech time duration of the input audio signal to a predetermined time; wherein said level changing control means comprises; first counter means for counting a total non-speech time duration and producing an output in accordance with an output from said comparator; second counter means for counting the time of the input audio signal and producing an output signal when a predetermined period of time has elapsed; and control signal generating means for outputting a control signal for altering the level of said comparator by a predetermined amount in response to the outputs from said first and second counter means; wherein said control signal generating means comprises; first latch means for latching the output from said first counter means and outputting the latched output depending on whether the total non-speech duration exceeds the predetermined period of time; and second latch means for latching the output from said second counter means and outputting a control signal for altering the judging level of said comparator by the predetermined amount in response to the output from said first latch means; wherein said second latch means comprises a plurality of latch circuits for respectively latching a plurality of outputs from said second counter means.
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6. A circuit for distinguishing between speech and non-speech signals for judging an input audio signal to be a non-speech signal when a level of the input audio signal is lower than a predetermined level and judging the input audio signal to be a speech signal when the level of the input audio signal is higher than the predetermined level, comprising:
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a comparator for comparing the level of the input audio signal with the predetermined level; and level changing control means for raising or lowering a level of the input audio signal input to said comparator by a predetermined amount in accordance with a ratio of a non-speech time duration of the input audio signal to a predetermined time. - View Dependent Claims (7, 8, 9, 10, 11)
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Specification