1960 年 16 巻 4 号 p. 283-285
A new method of pitch extraction using a digital computer, which is faster than the existing methods, has been proposed. "Locally almost periodic function" is adopted as the mathematical model for voiced speech wave, and the pitch frequency is defined as its "local peridicity". The existence and non-existence of the pitch, i. e. , "local periodicity", and its transition are determined by evaluating the newly defined measure of distance in time domain which is invariant under amplitude and other transformations. Possible application of this method might be for automatic speech recognition, a computer simulated vocoder system and general speech researches. This is a part of research efforts made under the Laboratory's research project "LOGOS".