Linguistic categories and speech perception

Do linguistic units have invariant
correlates
• There is no strong evidence that all linguistic
units, even of a single type, are invariantly and
reliably present in the speech signal
• Yet some acoustic-phonetic features are more
robust across contexts and speakers than
others i.e. their properties are a good deal
more invariant and reliable than others,
especially if they are considered in relation to
their surrounding context, and with respect to
known properties of the auditory system.