Résumé
Specifies the frequency for the note A in the treble stave and shall be 440 Hz. Tuning and retuning shall be effected by instruments producing it within an accuracy of 0,5 Hz.
Specifies the frequency for the note A in the treble stave and shall be 440 Hz. Tuning and retuning shall be effected by instruments producing it within an accuracy of 0,5 Hz.