concert pitch

In music, standard pitch to which concert ensembles tune up. In a symphony orchestra it is normally the pitch A4, which is common to instruments of the string orchestra. It is given by the oboe, otherwise by the concert master (principal violin) or deputy, or by the piano or organ if featured, as their tuning is fixed in advance.

In military and brass bands, concert pitch is B♭, for the reason that wind instruments in general are historically tuned to B♭ or a related dimension (the pitch of B♭ expressing a wavelength of specific measure).

The standard frequency associated with concert A4 pitch is 440 Hz (cycles per second) but this is subject to variation, some orchestras preferring 438 Hz, others tending towards 442 Hz, with slight but consequential effects on individual and ensemble tone. Prior to 1700 the pitch standard was local and set by the chapel organ, of which a number of Renaissance and baroque examples survive with values for A4 between a low extreme of 380 Hz and a high of 610 Hz. In 1862 Hermann Helmholtz gave a value for A4 of 431 Hz, an increase on 18th-century concert pitch. The revival of authentic early music practices after 1970 has led to agreement on standards of 460-465 Hz for High Renaissance music, 415 Hz for baroque and classical music, and 430 Hz for Romantic music.