Voiced dental, alveolar and postalveolar trills

The voiced alveolar trill is a type of consonantal sound used in some spoken languages. The symbol in the International Phonetic Alphabet that represents dental, alveolar, and postalveolar trills is ⟨r⟩, and the equivalent X-SAMPA symbol is r. It is commonly called the rolled R, rolling R, or trilled R. Quite often, ⟨r⟩ is used in phonemic transcriptions (especially those found in dictionaries) of languages like English and German that have rhotic consonants that are not an alveolar trill. That is partly for ease of typesetting and partly because ⟨r⟩ is the letter used in the orthographies of such languages.

In many Indo-European languages, a trill may often be reduced to a single vibration in unstressed positions. In Italian, a simple trill typically displays only one or two vibrations, while a geminate trill will have three or more.[1] Languages where trills always have multiple vibrations include Albanian, Spanish, Cypriot Greek, and a number of Armenian and Portuguese dialects.[citation needed]

People with ankyloglossia may find it exceptionally difficult to articulate the sound because of the limited mobility of their tongues.[2][3]

A trill extended for about 2 seconds by a non-native user, captured in slow motion to reveal the individual 36~44Hz tongue oscillations.

In Czech, there are two contrasting alveolar trills. Besides the typical apical trill, written r, there is another laminal trill, written ř, in words such as rybáři [ˈrɪbaːr̝ɪ] 'fishermen' and the common surname Dvořák. Its manner of articulation is similar to [r] but is laminal and the body of the tongue is raised. It is thus partially fricative, with the frication sounding rather like [ʒ] but less retracted. It sounds like a simultaneous [r] and [ʒ], and non-native speakers tend to pronounce it as [rʐ], [ɾʒ], or [ɹʒ]. In the IPA, it is typically written as ⟨r⟩ plus the raising diacritic, ⟨⟩, but it has also been written as laminal ⟨⟩.[42] (Before the 1989 IPA Kiel Convention, it had a dedicated symbol ⟨ɼ⟩.) The Kobon language of Papua New Guinea also has a fricative trill, but the degree of frication is variable.

Bender, Byron (1969), , University of Hawaii Press, ISBN 0-87022-070-5