Tuning
Tuning strings or pipes.
What it means
Tuning designates setting up an instrument to the correct pitch. With string instruments this happens by tightening or loosening the strings, with wind instruments by changing the tube length, with organs through interventions on the pipes, with the piano through the piano tuner with a tool of their own.
The process has two sides. On the one hand a reference pitch is fixed, today usually the note A above middle C at a particular frequency; on the other hand the remaining notes are set in relation to it. With instruments of fixed pitch, for instance keyboard instruments, the chosen temperament determines how the intervals stand to one another.
The word has further meanings in German — Stimmen as the individual parts of a score, or as singing voices — which are not meant here.
In the notation
Tuning itself is not notated. In scores, however, indications for retuning appear, for instance when a string of a bowed instrument is to be tuned differently from usual; the technical term for this is scordatura. With timpani, the required tuning notes stand at the beginning of the part and, at changes, at the point concerned.
Musical use
The question of pitch standard has changed in the course of history: the reference pitch stood at different heights at different times and in different places. In historically oriented performance practice, lower pitch standards are therefore often used than is customary today. In the orchestra, tuning is done together before every rehearsal and performance against a reference pitch, traditionally given by the oboe.
In the orchestra one tunes to the oboe's A, in an ensemble often to a keyboard instrument. Keyboard instruments are tuned by the tuner.
Performance practice
Tune calmly and before playing, not during others' entrance. Listen for beats: two almost identical notes create a flickering that disappears when they match. Check the tuning again during a longer rehearsal, since temperature and playing change it. And tune, in ensemble, to the shared reference pitch, not to your own tuner alone.