Glottal stop

There is one context where flapping of /t/ does not occur when preceded by a vowel and followed by an unstressed syllabic segment (vowel or syllabic sonorant), and that is when /t/ is followed by a syllabic [n̩]. Consider, first, examples such as [ˈbʌʔn̩ ] button and [ˈkaʔn̩ ] cotton. Instead of the flap that we expect, based on our understanding of the context where flapping takes place, we find glottal stop before syllabic [n̩ ]. Consider the following pairs of words:

The bare roots on the left show the underlying /t/ which has not changed to glottal stop, and on the right, we observe that the addition of the suffix /n/ conditions the change of /t/ to [ʔ] in the context ˈV_n, i.e. when t is preceded by a stressed vowel and followed by an alveolar nasal. Words like [ˈæɾm̩ ] atom show that the glottal stop rule does not apply before all nasals, just alveolar nasals.

Finally, notice that in casual speech, the gerundive suffix -ɪŋ may be pronounced as [n̩ ]. When the verb root ends in /t/, that /t/ becomes [ʔ] just in case the suffix becomes [n̩ ], and thus provides the crucial context required for the glottal stop creation rule.

In the examples considered so far, the environment for appearance of glottal stop has been a following syllabic [n̩ ]. Is it crucial that the triggering nasal segment be specifically a syllabic nasal? We also find glottal stop before nonsyllabic nasals in words such as Whitney [ʍɪʔnij] and fatness [fæʔnəs], which shows that the t-glottalization rule does not care about the syllabicity of the following nasal. The presence of glottal stop in these examples can be explained by the existence of a rule which turns /t/ into glottal stop before [n] or [n̩ ].

Notice that this rule applies before a set of segments, but not a random set: it applies before alveolar nasals, without mention of syllabicity. As we will repeatedly see, the conditioning context of phonological rules is stated in terms of phonetic properties.