Acoustic analyses of eight different languages/dialects had revealed a language universal: Three spectral factors consistently appeared in analyses of power fluctuations of spoken sentences divided by critical-band filters into narrow frequency bands. Examining linguistic implications of these factors seems important to understand how speech sounds carry linguistic information. Here we show the three general categories of the English phonemes, i.e., vowels, sonorant consonants, and obstruents, to be discriminable in the Cartesian space constructed by these factors: A factor related to frequency components above 3,300 Hz was associated only with obstruents (e.g.,/k/or/z/), and another factor related to frequency components around 1,100 Hz only with vowels (e.g.,/a/or/i/) and sonorant consonants (e.g.,/w/,/r/, or/m/). The latter factor highly correlated with the hypothetical concept of sonority or aperture in phonology. These factors turned out to connect the linguistic and acoustic aspects of speech sounds systematically.
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