Calculating Beat Frequency for Two Loudspeakers

[inflames829]

Homework Statement

Two loudspeakers face each other at opposite ends of a long corridor. They are connected to the same sourrce that produces a pure tone of 343Hz. A person walks from one speaker towards the other at a speed of 0.7ms-1
What beat frequency does the person hear?
speed of sound= 343ms-1

Homework Equations

The Attempt at a Solution

I know the beat frequency equals the frequency of one take the frequency of the second. So if this is right does that mean it is 343 minus the second frequency. Can someone pleasae tell me if this is correct and any hints on how to work out the second frequency please. Thankyou

 

[rl.bhat]

Using the doppler effect wright down the expression for the apparent freqency of the source heard by the observer while moving from one speaker to another. Note that he is going away from one speaker and moving towards the other.

 

[inflames829]

thanks for the help. I got the right answer