Asymmetries in consonant confusion

Both historical sound change and laboratory confusion studies show strong asymmetries of consonant confusions. In particular, /ki/ commonly changes to /ti/, and /pi/ to /ti/, but not the reverse. It is hypothesized that such asymmetries arise when two sounds are acoustically similar except for one or more differentiating cues, which are subject to a highly directional perceptual error. This perceptual entropy can be explained as follows: if sound x possesses a cue that y lacks, listeners are more likely to miss this "all-or-none" cue than to introduce it spuriously. /k/ and /t/ before /i/ have similar formant transitions but differ in their burst spectra. /p/ and /t/ before /i/ also have similar formant transitions but differ in the intensity of their bursts. The importance of these differentiating features for listeners’ perception were verified in a confusion study. The implications of the inversely related effects of perceptual and physical entropy for phonetic theory and speech technology is discussed.