Do Sound Waves Interact to Reduce Freeway Noise at Night?

[bassplayer142]

Does sound waves interact with each other and cancel each other out. I'm not talking about constructive or deconstructive interference either. If a strong sound source is pointed towards a weak one does the compression of air interact with other waves. I don't know if I asked it right or if anyone understands what I am trying to say. I'm wondering because from a mile away I can hear cars on a freeway at night yet I can't in the daytime. Whats the reason?

thanks

 

[hagopbul]

yes it intract with each other.but not nessery cancel each other out.

 

[lpfr]

I understand that it is not interferences that bother you.
For normal sounds, even intense sounds (140 dB) there is not other interaction than "interferences". At very high levels of sounds (shock waves, supersonic bangs, sound at a gun muzzle, etc.) you have another type of interaction: big waves shallow small ones. The reason is that the speed of sound depends on the temperature of air (higher temperature, higher speed). Big waves heat more the air and travel faster than small ones and overtake them. Once the small wave has been overtaken it travels in the hot air of the big one and continues at the same speed. This is a non linear effect that happens only in shock waves.
Then the reason you heard cars in the night and not in the day must be another. I see some possible explanations:
-- Background noise is bigger during the day.
-- Noise in the highway is louder during the night.
-- Wind is different. From de highway in the night, to the highway in the day.
Maybe there is another that I don't see.

 

[bassplayer142]

Thanks everyone.

 

[Jallu]

This has to do with refraction of the sound waves. The phenomenon is very well explained here:

http://www.kettering.edu/~drussell/Demos/refract/refract.html