# Doppler effect, source and receiver in different media

1. Mar 19, 2014

### nikolafmf

Hello,

For convenience, we can say that a submarine at some depth in sea emits sound wave which refracts from the surface of the sea and is caught by a helicopter at some height above the sea. If we know the speeds of the submarine and the helicopter and the frequency of the emitted wave (and, of course, the speed of the sound in water and air), how are we going to calculate the frequency of the received wave? I know how to use the Doppler shift's formulas when the wave travels all the time in a same media. But, when it changes media, it also changes its speed. How can we account for that?

Sincerely,
Nikola

2. Mar 19, 2014

### A.T.

Frequency is not afected by passing between media.

3. Mar 19, 2014

### nikolafmf

Yes, I know that. But in the formula for Doppler effect, wave speed occurs, as in the first formula here: http://en.wikipedia.org/wiki/Doppler_effect#General. And speed do changes by passing between media. So, how can I calculate received frequency?