The Alveolar Trill
The alveolar trill, also known as the "rolled r," is a very recognizable sound. It is common in the languages of the world, but not present in American or British English.
The alveolar trill is a tricky sound to make. It is typically one of the later sounds children learn when speaking a language. To make an alveolar trill, you must hold your tongue near your alveolar ridge. Then you need to phonate. If the body of the tongue is stiff but the tip is loose enough, the movement of the air will cause the tongue tip to make contact with the alveolar ridge, bounce off, and then hit it again. These multiple contacts are what characterize trills. Trills require a good amount of muscle control of the tongue, which is why they are difficult to learn for children and adults alike. Some conditions, such as ankyloglossia (a "tongue-tie"), can make it exceptionally hard to produce an alveolar trill (Kummer, 2013). Surgery may help in these cases.
The alveolar trill and the alveolar tap have a special relationship - in Indo-European languages one can usually substitute for the other without changing the meaning of the word (Quiles, 2009). In Russian, it does not matter if you say 'para' with a tapped 'r' or a trilled 'r'. Both are acceptable. There are some languages, however, where this actually makes a difference in the meaning of the word. In Spanish, 'r' and 'rr' are different sounds: 'caro' versus 'carro.' This is only in the middle of a word. If you are starting a word, you use the trill, and if it's at the end of a syllable, you may use either. Basque and Armenian also make this distinction between 'r' and 'rr'.
There are varieties of English with alveolar trills. Historically, English used to have an alveolar trill, which appears to have turned into an approximant around middle English (source). Old varieties of Irish English and Scottish English have a trilled r.
Alveolar trills are used in music for non-phonemic purposes. For example, in English-language songs alveolar trills can evoke Spanish. Songs by English speakers in a Latin genre can have exaggerated alveolar trills as an exotic sound.
Some varieties of languages don't really use alveolar trills in everyday spoken language, but use alveolar trills in elevated speech like political rhetoric, theatre, or song. For example, Standard German uses a uvular fricative for its 'r' sound. But in Stage German or Bühnendeutsch, the 'r's are trilled instead (Mangold, 2005). In English Received Pronunciation, 'r's can occasionally be trilled (Jones, 2011). More generally in English-language classical music, singers may use a trilled 'r' instead of an alveolar r (Journal of Singing).
Alveolar trills can be used for aesthetic reason or emphasis. In some languages, they also have interesting associations. Alveolar trills in Japanese are associated with aggressive speech and violent characters.
Examples of Alveolar Trills
Nicki Minaj uses an alveolar trill as part of her producer tag on 'Anaconda.'
Bradley Nowell from Sublime uses an alveolar trill in the second chorus of the song 'Doin' Time':"Rrrrun to the party and dance to the rhythm"
Alveolar trills are hard to make, but certainly fun to perform. if you've seen any interesting or unusual instances of an alveolar trill out and about, post in the comments!