Some Examples from Electro-Acoustic Practice

Abstract

In this field too the cathode ray oscilloscope can be used to great advantage in many types of measurement and investigation. For instance, the precise calibration of tuning forks and the tuning of musical instruments, indeed, of whole orchestras, has been carried out by means of oscilloscopes and duly described [1] [2]. tak has described the measurement of the reverberation time of a room, in which the reverberation of sound pulses is picked up by microphones, the resulting voltage amplified exponentially and displayed with an oscilloscope [3] [4]. The rhythm of the shock waves and the exponential gain increases are controlled by the time base voltage of the oscilloscope. If the time base frequency is adjusted so that the oscillogram has a roughly constant amplitude throughout the whole width of the pattern, then the reverberation time is equal to the duration of one time base cycle. In this way the dependence of the reverberation time upon the frequency of the sound pulses can be investigated.