Apparatus and method for determining the beginning and the end of a speech utterance

Claim 2

Apparatus for determining a boundary of an applied speech utterance comprising: means for adaptive encoding said applied speech utterance to develop coded output signals; means for developing a signal representative of the energy of said coded output signals; and means for comparing said representative signal with a predetermined threshold signal.

Claim 3

The apparatus defined in claim 1 wherein said signal representative of the energy of said cOded output signals is representative of the adaptation activity of said means for adaptive encoding.

Claim 4

The apparatus defined in claim 1 wherein said threshold signal is representative of an energy level intermediate the energy of background silence and the average energy of said speech utterance.

Claim 5

Apparatus for determining a boundary of an applied speech utterance comprising: means for adaptive differential pulse code modulating said applied speech utterance to develop digitally coded output signals; means for developing a signal representative of the energy of said coded output signals; and means for comparing said representative signal with a predetermined digital threshold signal.

Claim 6

Apparatus for determining a boundary of an applied speech utterance comprising: means for adaptive differential pulse code modulating said applied speech utterance to develop digitally coded output signals; means for developing a signal representative of the energy of said coded output signals; and means for comparing said representative signal with a predetermined digital threshold signal.

Claim 7

The apparatus defined in claim 4 wherein said signal representative of the energy of said coded output signals is defined as the sum of the squares of a predetermined number of said digitally coded output signals.

Claim 8

The apparatus defined in claim 4 wherein said digital threshold signal is representative of an energy level intermediate the energy of background silence and the average energy of said speech utterance.

Claim 9

Apparatus for detecting the beginning of a speech utterance, including an adaptive differential pulse code modulation circuit responsive to said speech utterance, comprising: means responsive to the digitally coded output signals of said modulation circuit for developing a digital signal representative of the energy of said coded output signals; and means responsive to said representative signal for developing an output signal when said representative signal is greater than, for a predetermined interval of time, an applied digital threshold signal, said output signal indicative of the beginning of said speech utterance.

Claim 10

Apparatus for detecting the beginning of a speech utterance, including an adaptive differential pulse code modulation circuit responsive to said speech utterance, comprising: means responsive to the digitally coded output signals of said modulation circuit for developing a digital signal representative of the energy of said coded output signals; and means responsive to said representative signal for developing an output signal when said representative signal is greater than, for a predetermined interval of time, an applied digital threshold signal, said output signal indicative of the beginning of said speech utterance.

Claim 11

The apparatus defined in claim 7 wherein said signal representative of the energy of said coded output signals is defined as the sum of the squares of a predetermined number of said digitally coded output signals.

Claim 12

The apparatus defined in claim 7 wherein said digital threshold signal is representative of an energy level intermediate the energy of background silence and the average energy of said speech utterance.

Claim 13

The apparatus defined in claim 7 wherein said means for developing a signal representative of the energy of said digitally coded output signals comprises: first means for doubling each digitally coded output signal of said modulation circuit; second means for subtracting from each of said doubled coded output signals a predetermined digital reference signal; third means for squaring each output signal of said second means; fourth means for sequentially storing a predetermined number of said squared signals; fifth means for subtracting from the most recently stored squared signal in said fourth means the oldest stored squared signal in said fourth means; sixth means for adding the output signal of said fifth means and an applied signal to develop a signal representative of the energy of said coded output signals; and seventh means for applying said representative signal to said sixth means after a predetermined interval of time has elapsed.

Claim 14

Apparatus for determining the beginning of a speech signal, including an adaptive differential pulse code modulation circuit responsive to said speech signal, comprising: means responsive to the output signals of said modulation circuit for developing a signal representative of the energy of said output signals; and means responsive to said representative signal for developing an indicator signal when said representative signal is greater than, for a predetermined interval of time, an applied threshold signal, said indicator signal indicative of the beginning of said speech signal.

Claim 15

Apparatus for determining the beginning of a speech signal, including an adaptive differential pulse code modulation circuit responsive to said speech signal, comprising: means responsive to the output signals of said modulation circuit for developing a signal representative of the energy of said output signals; and means responsive to said representative signal for developing an indicator signal when said representative signal is greater than, for a predetermined interval of time, an applied threshold signal, said indicator signal indicative of the beginning of said speech signal.

Claim 16

Apparatus for detecting the end of a speech utterance, including an adaptive differential pulse code modulation circuit responsive to said speech utterance, comprising: means responsive to the digitally coded output signals of said modulation circuit for developing a digital signal representative of the energy of said coded output signals; and means responsive to said representative signal for developing an output signal when said representative signal is less than, for a predetermined interval of time, an applied digital threshold signal, said output signal indicative of the end of said speech utterance.

Claim 17

Apparatus for detecting the end of a speech utterance, including an adaptive differential pulse code modulation circuit responsive to said speech utterance, comprising: means responsive to the digitally coded output signals of said modulation circuit for developing a digital signal representative of the energy of said coded output signals; and means responsive to said representative signal for developing an output signal when said representative signal is less than, for a predetermined interval of time, an applied digital threshold signal, said output signal indicative of the end of said speech utterance.

Claim 18

The apparatus defined in claim 12 wherein said signal representative of the energy of said coded output signals is defined as the sum of the squares of a predetermined number of said digitally coded output signals.

Claim 19

The apparatus defined in claim 12 wherein said digital threshold signal is representative of an energy level intermediate the energy of background silence and the average energy of said speech utterance.

Claim 20

The apparatus defined in claim 12 wherein said means for developing a signal representative of the energy of said digitally coded output signals comprises: first means for doubling each digitally coded output signal of said modulation circuit; second means for subtracting from each of said doubled coded output signals a predetermined digital reference signal; third means for squaring each output signal of said second means; fourth means for sequentially storing a predetermined number of said squared signals; fifth means for subtracting from the most recently stored squared signal in said fourth means the oldest stored squared signal in said fourth means; sixth means for adding the output signal of said fifth means and an applied signal to develop a signal representative of the energy of said coded output signals; and seventh means for applying said representative signal to said sixth means after a predetermined interval of time has elapsed.

Claim 21

Apparatus for determining the end of a speech signal, including an adaptive differential pulse code modulation circuit responsive to said speech signal, comprising: means responsive to the output signals of said modulation circuit for developing a signal representative of the energy of said output signals; and means responsive to said representative signal for developing an indicator signal when said representative signal is less than, for a predetermined interval of time, an applied threshold signal, said indicator signal indicative of the end of said speech signal.

Claim 22

Apparatus for determining the end of a speech signal, including an adaptive differential pulse code modulation circuit responsive to said speech signal, comprising: means responsive to the output signals of said modulation circuit for developing a signal representative of the energy of said output signals; and means responsive to said representative signal for developing an indicator signal when said representative signal is less than, for a predetermined interval of time, an applied threshold signal, said indicator signal indicative of the end of said speech signal.

Claim 23

Apparatus for detecting the boundaries of a speech utterance, including an adaptive differential pulse code modulation circuit responsive to said speech utterance, comprising: code word energy means responsive to the digitally coded output signals of said modulation circuit for developing a digital signal representative of the energy of said coded output signals; comparator means for comparing said digital representative signal with an applied digital threshold signal; and means responsive to said comparator means for developing a signal indicative of the beginning of said speech utterance when said representative signal is greater than, for a first predetermined interval of time, said threshold signal, and for developing a signal indicative of the end of said speech utterance when said representative signal is less than, for a second predetermined interval of time, said threshold signal.

Claim 24

Apparatus for detecting the boundaries of a speech utterance, including an adaptive differential pulse code modulation circuit responsive to said speech utterance, comprising: code word energy means responsive to the digitally coded output signals of said modulation circuit for developing a digital signal representative of the energy of said coded output signals; comparator means for comparing said digital representative signal with an applied digital threshold signal; and means responsive to said comparator means for developing a signal indicative of the beginning of said speech utterance when said representative signal is greater than, for a first predetermined interval of time, said threshold signal, and for developing a signal indicative of the end of said speech utterance when said representative signal is less than, for a second predetermined interval of time, said threshold signal.

Claim 25

Apparatus for determining the boundaries of a speech signal, including an adaptive differential pulse code modulation circuit responsive to said speech signal, comprising: code word energy means responsive to the output signals of said modulation circuit for developing a signal representative of the energy of said output signals; comparator means for comparing said representative signal with an applied threshold signal; and means responsive to said comparator means for developing a signal indicative of the beginning of said speech signal when said representative signal is greater than, for a first predetermined interval of time, said threshold signal, and for developing A signal indicative of the end of said speech signal when said representative signal is less than, for a second predetermined interval of time, said threshold signal.

Claim 26

Apparatus for determining the boundaries of a speech signal, including an adaptive differential pulse code modulation circuit responsive to said speech signal, comprising: code word energy means responsive to the output signals of said modulation circuit for developing a signal representative of the energy of said output signals; comparator means for comparing said representative signal with an applied threshold signal; and means responsive to said comparator means for developing a signal indicative of the beginning of said speech signal when said representative signal is greater than, for a first predetermined interval of time, said threshold signal, and for developing A signal indicative of the end of said speech signal when said representative signal is less than, for a second predetermined interval of time, said threshold signal.

Claim 27

Apparatus for detecting the boundaries of a speech utterance, including an adaptive differential pulse code modulation circuit responsive to said speech utterance, comprising: code word energy means responsive to the digitally coded output signals of said modulation circuit for developing a digital signal representative of the energy of said coded output signals; and means for developing a signal indicative of the beginning of said speech utterance when said representative signal is greater than an applied digital threshold signal for a first predetermined interval of time, and for developing a signal indicative of the end of said speech utterance when said representative signal is less than said applied threshold signal for a second predetermined interval of time.

Claim 28

Apparatus for detecting the boundaries of a speech utterance, including an adaptive differential pulse code modulation circuit responsive to said speech utterance, comprising: code word energy means responsive to the digitally coded output signals of said modulation circuit for developing a digital signal representative of the energy of said coded output signals; and means for developing a signal indicative of the beginning of said speech utterance when said representative signal is greater than an applied digital threshold signal for a first predetermined interval of time, and for developing a signal indicative of the end of said speech utterance when said representative signal is less than said applied threshold signal for a second predetermined interval of time.

Claim 29

The apparatus defined in claim 19 wherein said signal representative of the energy of said coded output signals is defined as the sum of the squares of a predetermined number of said digitally coded output signals.

Claim 30

The apparatus as defined in claim 19 wherein said digital threshold signal is representative of an energy level intermediate the energy of background silence and the average energy of said speech utterance.

Claim 31

The apparatus defined in claim 19 wherein said means for developing a signal representative of the energy of said coded output signals comprises: first means for doubling each digitally coded output signal of said modulation circuit; second means for subtracting from each of said doubled coded output signals a predetermined digital reference signal; third means for squaring each output signal of said second means; fourth means for sequentially storing a predetermined number of said squared signals; fifth means for subtracting from the most recently stored squared signal in said fourth means the oldest stored squared signal in said fourth means; sixth means for adding the output signal of said fifth means and an applied signal to develop a signal representative of the energy of said coded output signals; and seventh means for applying said representative signal to said sixth means after a predetermined interval of time has elapsed.

Claim 32

The apparatus defined in claim 19 wherein said means for developing said indicative signals comprises: digital comparator means responsive to said signal representative of the energy of said coded output signals and to said applied digital threshold signal for developing a signal at a first output terminal when said representative energy signal is greater than said threshold signal and for developing a signal at a second output terminal when said representative energy signal is less than said threshold signal; a bistable circuit having first and second output terminals, and set and reset terminals; a first logic circuit responsive to said comparator first output terminal signal and to the signal at the first output terminal of said bistable circuit; a second logic circuit responsive to said comparator second output terminal signal and to the signal at the second output terminal of said bistable circuit; a third logic circuit responsive to the output signals of said first and second logic circuits; a fourth logic circuit responsive to the output signal of said third logic circuit and to an applied clock signal; a counter circuit, having a plurality of output terminals, responsive to the output signal of said fourth logic circuit; a fifth logic circuit, for developing said signal indicative of the end of said speech utterance, responsive to the signal at the second output terminal of said bistable circuit and to the signal at a preselected one of said plurality of counter circuit output terminals; a sixth logic circuit, for developing said signal indicative of the beginning of said speech utTerance, responsive to the signal at the first output terminal of said bistable circuit first and to the signals at the other of said plurality of counter circuit output terminals; a seventh logic circuit responsive to the output signals of said third, fifth, and sixth logic circuits for developing a control signal for said counter circuit, said control signal returning said counter to a predetermined initial state; and means for connecting the output terminals of said fifth and sixth logic circuits, respectively, to said set and reset terminals of said bistable circuit.

Claim 35

The method defined in claim 24 wherein said signal representative of the energy of said coded output signals is defined as the sum of the squares of a predetermined number of said digitally coded output signals.

Claim 36

The method defined in claim 24 wherein said digital threshold signal is representative of an energy level intermediate the energy of background silence and the average energy of said speech utterance.