Trill consonant

In phonetics, a trill is a consonantal sound produced by vibrations between the active articulator and passive articulator. Standard Spanish <rr> as in perro, for example is an alveolar trill.

Trills are very different from flaps. Whereas with a flap (or tap), a specific gesture is used to strike the active articulator against the passive one, in the case of a trill the articulator is held in place, where the airstream causes it to vibrate. Usually a trill vibrates for 2–3 periods, but may be up to 5, or even more if geminate. However, trills may also be produced with only a single period. Although this might seem like a flap, the articulation is different; trills will vary in the number of periods, but flaps do not.

Trill consonants included in the International Phonetic Alphabet:

In addition,

The bilabial trill is uncommon. The coronal trill is most frequently alveolar [r͇], but dental and postalveolar articulations [r̪] and [r̠] also occur. An alleged retroflex trill found in Toda has been transcribed [ɽ] (that is, the same as the retroflex flap), but might be less ambiguously written [ɽ͡r], as only the onset is retroflex, with the actual trill being alveolar. The epiglottal trills are identified by the IPA as fricatives, with the trilling assumed to be allophonic. However, analyzing the sounds as trills may be more economical. There are also so-called strident vowels which are accompanied by epiglottal trill.

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