Extracting a carrier-independent version of the syllabic message: The principles

• Published in: The Journal of the Acoustical Society of America 2005-04, Vol.117 (4_Supplement), p.2373-2373
• Main Authors: Patterson, Roy D., Walters, Thomas C., Irino, Toshio
• Format: Article
• Language: English
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.4785617

At the heart of each syllable of speech is a vowel; the wave consists of a stream of glottal pulses, each with a resonance attached. The vowel contains three important components of the information in the larger communication: the glottal pulse rate (the pitch), the resonance shape (the message), and the resonance scale (the vocal tract length). Recent experiments on the perception of vowels show that variability in glottal pulse rate and vocal tract length has surprisingly little effect on the humans ability to recognise the vowel or discriminate speaker size, despite the variability it imparts to the spectra of these sounds. We appear to have an automatic normalization process to scale vowels and extract the message independent of the carrier. Many animal calls are like syllables in form and duration, and normalization is essential here as well if animals are to correctly identify the species of the sender and not be confused by changes in pulse rate and resonance scale that simply indicate a size difference. This talk describes how neural firing patterns produced by vowels and animal calls could be normalized to produce a carrier independent version of the message of the syllable. [Work supported by UK MRC.]