Characteristics of electronic circuit for examining variations in vocal excitation for diagnostic purposes and in speech recognition for determiniog voice patterns and pitch changes are described. Operation of the circuit is discussed and circuit diagram is provided

Babcock, M. L.

Cohen, J.

English

NASA Technical Reports Server

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October 1972	 B72-10652 
NASA TECH BRIEF 
NASA Headquarters	 W 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Speech Therapy and Voice Recognition Instrument 
The instrument shown by the block diagram auto-
matically extracts the time between glottal pulses (present 
during the voiced portions of speech) from the complex 
time-pressure waveform of natural speech, and auto-
matically separates the voiced and nonvoiced portions of 
speech. The system should prove useful in speech path-
ology, for examining variations in vocal excitation for 
diagnostic purposes, and in speech recognition, for deter-
mining voice patterns and pitch changes. 
The signal input is either a speech waveform or the 
derivative of the waveform, taken usually from a micro-
phone output. A threshold device senses the waveform at 
a value approximately 309/o either above or below the
average value, and produces a time marker when a 
negative-going transition occurs through the defined 
threshold. The time between consecutive time markers is 
measured, and an algorithm is applied to these intervals. 
The first time interval between the time markers is 
compared to a reference "stop number" of approximately 
3-ms duration. If the interval is greater than the stop 
number, the interval is defined as an output and is 
processed accordingly. If it is less than the stop number, 
the first interval is added to the second interval to form a 
continuing sum. The second interval is then compared to 
the stop number; if it is greater than the stop number, the 
sum is recorded as output. If it is less, the continuing sum 
is added to the third interval, and so on. 
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(continued overleaf) 
This document was prepared under the sponsorship of the National 	 Government assumes any liability resulting ti the use of the 
Aeronautics and Space Administration. Neither the United States	 information contained in this document, or warrants that such use 
Government not' any person acting on behalf of the United States 	 will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19720000651 2020-03-17T03:41:23+00:00Z
Each time an output occurs, the continuing sum is 
reset to zero, and the algorithm is repeated. The output is 
a series of times which are direct measurements of 
intergiottal intervals. Because of the sampling method, 
nonvoice portions of speech result in large time intervals 
which are easily distinguished from the glottal intervals. 
The electronic system is readily implemented with 
standard digital circuitry. The output may be recorded on 
a variety of visual devices such as a cathode ray 
oscilloscope for average values, while pictures of high-
persistence displays may be used to define exact interval 
times.
Note: 
Requests for further information may be directed to: 
Technology Utilization Officer 
Code KT 
NASA Headquarters 
Washington, D. C. 20546 
Reference: B72.10652 
Patent status: 
NASA has decided not to apply for a patent. 
Source: J. Cohen and M. L. Babcock of
University of fflinois 
under contract to
NASA Headquarters
(HQN- 10628) 
B72-10652	 Category 05


Speech therapy and voice recognition instrument

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