Question

an oboe plays A (440 Hz) at 20degrees Celsius. at the same time, an identical oboe plays the same note at 0degrees, and beats are heard. what is the beat frequency ?

Answer 1

Nice question.
\[ v = \lambda f \]
f is the same for the two notes. So what's different?

Answer 2

would \[\lambda\] be whats different ?

Answer 3

yes, it must be. Now why? Because v is different. Why? Because the speed of sound depends on the temperature of the air.