On the other hand, the types and degrees of phonetic contrast (e.g. whether all the consonants come in voiced and unvoiced pairs) have nothing to do with the classification of the phonemes; hence they do not constitute a necessary patterning. This is not to say that phonetic comparisons of the phonemes may not be interesting. It may indeed be desirable to work out patterns of the phonetic relations between phonemes and see how they compare with the distributional pattern. But that would be a new correlation, interesting for diachronic linguistic psychology, e.g. for the question: How do the physical (phonetic) differences within the ranges of phonemes (events to which people conventionally react uniformly) compare with the differences between different phonemes (events to which they react differently)?
- Harris (1941), a pag.348