Konserttonen
Konserttonen, or the concert pitch, is the standard reference frequency used to tune musical instruments before performances. The most widely adopted value today is A4 = 440 Hz, defined by international standards such as ISO 16: Standard Musical Pitch. In practice, orchestras and choirs tune their instruments by using an oboe or a tuning device to emit A4, and players adjust to that pitch at the start of a concert.
Historically, there was no single konserttonen. Pitch varied by country, city and era, and even within ensembles.
The choice of konserttonen influences instrument construction, string tension, and playing technique, as well as the
Related terms include concert pitch, standard pitch, and A440.