Asymmetries in consonant confusion

Abstract

Both historical sound change and laboratory confusion studies show strong asymmetries of consonant confusions. Historically [ki] commonly changes to [t∫i] (e.g., English chill, cognates with cool), but not the reverse. Similarly, Winitiz et al. [J. Acoust. Soc. Am. 51, 1309–1317 (1972)] in a consonant confusion study, found [ki] confused with [ti] more often than the reverse. It is hypothesized that such asymmetries arise when two sounds are acoustically similar except for one or more differentiating cues, which cues are subject to a highly directional perceptual error. For example, if soundx possesses a cue that y lacks, listeners are more likely to miss that cue than introduce it spuriously. /k/ and /t/ before /i/ have similar formant transitions but differ in their burst spectra: /k/ has a sharp mid-frequency peak that /t/ lacks. Listeners are more likely to miss the spectral peak for /k/ than introduce it in the burst of /t/. These consonant confusion studies of Italian syllables support this hypothesis: Italian listeners confused /ki/ with /ti/ with increasing asymmetry when the S/N ratio increased (where noise masks the burst more than the formant transitions) and when the burst was excised completely. Implications for phonetic theory and speech technology will be discussed.