# Destructive Interference

1. Dec 19, 2004

### Gentec

Good day

I have tried the following problem a few times and come up with ansers larger than 3.20m.

The problem: Two speakers are 3.20m apart and facing the same direction and are in phase. They each produce a 214Hz tone. What is the shortest distance directly in front of one speaker where there would be destructive interference? S of Sound is 343 m/s

Am I correct in using m=0?

Thanks for your time

2. Dec 19, 2004

### PeteTully

destructive interference between two waves occurs at m+(1/2) where m=0,1,2,3,...

so, m=0 would be incorrect.

3. Dec 20, 2004

### rayjohn01

confused

Hi Gentec
That's a very interesting question -- have you ever been in a room with zero sound from two speakers.
Although they are waves they are Longitudinal I cannot see how such two waves can cancel (in front of one speaker ) being that their directions are very different -- by destructive do you mean minimal sound or zero sound ?
Transverse waves ( to me can cencel irrispective of direction ) but longitudinal I can only see cancelling if they are in the SAME direction .
As I say confused
Ray.

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