Description:A standard bench oscillator is set up to produce a square wave that is narrowed into a series of pulses. This series of pulses from the oscillator is input into a small loudspeaker and picked up by a microphone. The oscilloscope is triggered by the pulses to the loudspeaker, but also displays the signal from the microphone. If the microphone is moved away from the loudspeaker, the signal picked up by the microphone will be delayed in time, shifting to the right on the scope. The speed of sound is the distance the microphone is moved divided by the time shift of a pulse on the oscilloscope, as measured by the oscilloscope reticule gridlines. Start with narrow pulses around 500 Hz and a scope time scale of about 500 microseconds per division.