The Ultimate Alveolar trill - American History Information Guide and Reference

The alveolar trill is a type of consonantal sound, used in some spoken languages (eg. Spanish and Polish). The symbol in the International Phonetic Alphabet that represents this sound is r, and the equivalent X-SAMPA symbol is r.

Features

Features of the alveolar trill:

Its manner of articulation is trill, which means it is produced by vibrations of the tongue against the place of articulation.
Its place of articulation is alveolar which means it is articulated with the tip of the tongue against the alveolar ridge.
Its phonation type is voiced, which means the vocal cords are vibrating during the articulation.
It is an oral consonant, which means air is allowed to escape through the mouth.
It is a central consonant, which means it is produced by allowing the airstream to flow over the middle of the tongue, rather than the sides.
The airstream mechanism is pulmonic egressive, which means it is articulated by pushing air out of the lungs and through the vocal tract, rather than from the glottis or the mouth.

There is also a voiceless version r ̥ occurring as rh in Welsh, and probably occurring as an allophone of r in ancient Greek.