All the consonants described so far, with the exception of h, belong to pairs distinguished by the difference between fortis and lenis. Since the remaining consonants to be described are not paired in this way, a few points that still have to be made about fortis consonants.

The first point concerns the shortening of a preceding vowel by a syllable-final fortis consonant. As was said earlier, the effect is most noticeable in the case of long vowels and diphthongs, although it does also affect short vowels. What happens if something other than a vowel precedes a fortis consonant? This arises in syllables ending with l, m, n, ŋ, followed by a fortis consonant such as p, t, k as in 'belt' belt, 'bump' bΛmp, 'bent' bent, 'bank' bæŋk. The effect on those continuant consonants is the same as on a vowel: they are considerably shortened.

Fortis consonants are usually articulated with open glottis - that is, with the vocal folds separated. This is always the case with fricatives, where airflow is essential for successful production. However, with plosives an alternative possibility is to produce the consonant with completely closed glottis. This type of plosive articulation, known as glottalisation, is found widely in contemporary English pronunciation, though only in specific contexts. The glottal closure occurs immediately before p, t, k, ʧ. The most widespread glottalisation is that of ʧ at the end of a stressed syllable (I leave defining what "stressed syllable" means). If we use the symbol ʔ to represent a glottal closure, the phonetic transcription for various words containing ʧ can be given as follows:

There is similar glottalisation of p, t, k, although this is not so noticeable. It normally happens when the plosive is followed by another consonant or a pause; for example:

Learners usually find these rules difficult to learn, from the practical point of view, and find it simpler to keep to the more conservative pronunciation which does not use glottalisation. However, it is worth pointing out the fact that this occurs - many learners notice the glottalisation and want to know what it is that they are hearing, and many of them find that they acquire the glottalised pronunciation in talking to native speakers.