Flapping in American English is a very robust phonological process where underlying alveolar stops are instead produced as alveolar flaps intervocalically where the first vowel is stressed (DeJong, 1998). However, in fast speech, flapping occurs unpredictably in a much greater variety of phonological environments, at such high rates that "parsing reduction is the norm” (Warner & Tucker, 2010). It is no accident that non-phonological reduction is rampant in faster speech; Dalby (1986) argues that reduction of this sort is an articulatory strategy that speakers use to increase their speech rate. Flapping as a means of reducing articulatory effort and rate of production is a good one in American English. Not only are flaps non-contrastive in American English (meaning that the chance of incorrect parsing is much lower) but flaps also take approximately half as long to produce as a full stop (Zue, 1979). This presents a problem, however. Monolingual speaker of English are presented with non-phonological reduction with high frequency, and are furthermore not linguistically compelled to differentiate between alveolar stops and flaps since flaps are non-contrastive. Are they, then, capable of perceiving the difference between phonological and non-phonological reduction?
Through three perceptual experiments, this study reveals that listeners are capable of perceiving these differences and, finally, that they react to the differences differently when the utterances are produced at different rates