Measuring the Speed of Sound

Drag the microphone to set a distance from the speaker, then read the distance off the Distance readout.
Press Play to make a sound and start the timer. The timer stops automatically when the sound reaches the microphone.
Record the distance and time in the results table.
Repeat for at least five different distances, spread evenly across the slider's range.
For each row, calculate the speed using v = d ÷ t.
Plot a graph of distance (m) against time (s). What does the gradient of this graph represent?
Do your calculated speeds agree with the accepted speed of sound in air (about 343 m/s)? Suggest one reason for any difference.