Asymmetries in consonant confusion

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.