Determining the speed of sound in air

[Freefeynman123]

Hello!

I have a problem with determining speed of sound basing on a data from laboratory.

1. Homework Statement

I have to determine speed of sound by measuring the shift of time in microphone compared to speaker. The distance between them is constant and I'm changing the frequency in generator, the results are:

Frequency [kHz] Shift [us]
6,42 0
6,91 68
7,41 22
7,88 20
8,4 68
8,88 2
9,425 42
9,9 23

The distance is S = 0,03 [m]

Homework Equations

I think that probably:

t = a*f + b

where t is time shift and f is frequency

The Attempt at a Solution

I tried to fit a line to the results, but I cannot interpret the output.

Can someone help me? I would be very pleased.

 

[Simon Bridge]

What does the experiment mean by "shift in time"?
i.e. what is the physical process that gives rise to the time shift you observe?