Spoken language travels from speaker to hearer as a sound wave. That sound wave is an extremely rich source of information. Without ever seeing a speaker we can often deduce correctly that person’s sex, region of origin (from their accent), emotional state (e.g. whether they are happy, sad, or angry), approximate age, and so on. If the speaker is someone known to us we may be able to identify him or her as an individual from their voice and way of talking. There is, of course, linguistic information encoded in the speech wave too. This includes information about individual words, but in addition the syntactic boundaries of sentences or clauses are often signalled by pauses or changes in voice pitch, and even the transition from one general topic to another may be marked in a similar way (Ellis & Beattie, 1986).