Certain vocalizations of birds, characteristic of males during the breeding season, for the attraction of a mate and for territorial defense. Birdsong also reinforces pair bonds, and some species have a flight song. Birdsongs are usually more complex and longer than birdcalls, which are used for communication within a species. Birdsong may be hereditary or learned; a newly hatched male chaffinch, for example, can sing a “subsong” but must learn to sing the true song by listening to and imitating adult males.

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U.S. a cappella singing style incorporating many folk hymns and utilizing a special musical notation. The seven-note scale used by some singers is sung not to the syllables do-re-mi-fa-sol-la-ti but to a four-syllable system brought to America by early English colonists: fa-sol-la-fa-sol-la-mi. The system reflects the fact that a series of three intervals repeats itself in the major scale. A differently shaped note head is used for each of the four syllables. The singer reads the music by following the shapes; singers unfamiliar with the system can read the notes according to their placement on the staff. The tradition started in New England and moved South and West as more sophisticated forms of music reached the U.S. Shape-note singing had largely died out except in rural areas by the 1880s, but it has experienced a revival in recent years. The traditional shape-note hymnal, The Sacred Harp, first published in 1844, remains in use today.

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Popular vocal ensemble consisting of four unaccompanied male voices. The voice parts are tenor, lead, baritone, and bass, with the lead normally singing the melody and the tenor harmonizing above. The emphasis is on close harmony, synchronization of word sounds, and variation of tempo, volume, diction, and phrasing. Barbershop apparently originated in the U.S. in the late 19th century, when American barbershops formed social and musical centres for neighbourhood men, though the term may derive from “barber's music,” the British term for an extemporized performance by patrons waiting to be shaved and referring to a barber's traditional role as a musician.

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