what happens if two sounds of same frequencies combine?

Answer 1

You end up with a sound of the same frequency, but with a change in amplitude dependent on the phases of the incoming signals.

You can prove it intuitively easily using Fourier theory... since F[a + b] = F[a] + F[b] (F[.] = Fourier transform of .), then you can't get frequencies in [a + b] that aren't present in [a] or [b], hence you get some scaled version of the frequencies in both F[a] and F[b] (which are the same from your question).

To show it mathematically, I'd use Euler...
Let both signals have frequency = w.
One has phase "p" radians, the other "q" radians:

2cos(wt + p) = exp(j (wt + p) ) + exp(-j (wt + p))
= exp(jp) exp(jwt) + exp(-jp) exp(-jwt)

2cos(wt + q) = exp(jq) exp(jwt) + exp(-jq) exp(-jwt)

2cos(wt + p) + 2cos(wt + q) = [exp(jq) + exp(jp)]exp(jwt) + [exp(-jq) + exp(-jp)]exp(-jwt)

Then, for some A and r that I can't be bothered to work out (you can convert to real/imag parts, add, then go back to polar if you really want):
[exp(jq) + exp(jp)] = A exp(jr)
[exp(-jq) + exp(-jp)] = A exp(-jr)
(you can show yourself that without doing the maths by drawing it in vector form)

...hence...
2cos(wt + p) + 2cos(wt + q) = A exp(jwt + r) + A exp(-jwt - r)
= 2A cos(wt + r)

Answer 2

Sound is waves of air pressure. At any point in space and time, they add, either constructively or destructively. Picture the two sources as the center of ripples on a pond. In still, open air, there are places where they are in phase and louder; in other places, they are out of phase and silent. The situation in a room with reflections is more complex.

Answer 3

The sounds become silent if they are in reverse amplitude but they are with same amplitude then they remain same.

Answer 4

If they are synchronize in phase the signal will be stronger, if they are not the signal will be noisy, if the signals are 180° out of phase they will cancel each other.

Answer 5

it depends on the phase difference it might produce a constructive interference or negative interference viz it may reinforce the amplitude or nullify it

Answer 6

It becomes louder because the amplitudes are added together.

Answer 7

boom!! it would collide and you would hear a mix of the two sounds. In case of mach speeds, you might hear sonic boom!!

Answer 8

clashesssss...thud..thud..thud, u cannot hear anything properly...