1098: Sound Shifts from Stress (s.s.w.3) Dec 11, 2017

Stress affects the way that certain sounds are produced fairly often, insofar as accentuation makes certain sounds more or less simple to create; whether or not one's emotional state changes one's speech is a different matter. For instance, historically, unstressed or lax vowels before an initial [h] would have led to the reduction of [h] entirely, so 'have' would have become [æv] but 'hay' would likely remain [heɪ]. This is related to why it is acceptable to say 'an historic...' or 'a historic...'. Moreover, many of the words sound the way they do today because unstressed or long vowels would often diphthongize, so an [æ] in 'has' (or 'hasn't) cold become [ɛ] as in 'bed', and then [e] to [eɪ] as in 'hey'. This is one proposed reason for how 'hasn't' could become 'ain't', or less controversially why 'have' does not rhyme with its derivative 'behave'.

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