A modulation-demodulation model of speech communication
Nobuaki Minematsu · 2010
Perceptual invariance against a large amount of acoustic variability in speech has been a long-discussed question in speech science and engineering [1] and it is still an open question [2,3].Recently, we proposed a candidate answer to it based on mathematically-guaranteed relational invariance [4, 5].Here, completely transform-invariant features, f -divergences, are extracted from speech dynamics of an utterance and they are used to represent that utterance.In this paper, this representation is interpreted from a viewpoint of telecommunications and evolutionary anthropology.Speech production is often regarded as a process of modulating the baseline timbre of a speaker's voices by manipulating the vocal organs, i.e., spectrum modulation.Then, extraction of the linguistic content from an utterance can be viewed as a process of spectrum demodulation.This modulation-demodulation model of speech communication has a good link to known morphological and cognitive differences between humans and apes.The model also claims that a linguistic content is transmitted mainly by supra-segmental features.