general sound question

[Pamplemousse123]

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its a long time since i've reviewed sound waves, but i figured i'd start by asking some questions with a stream-of-consiousness technique (forgive my blabber for that reason):

if someone wears a helmet and an alarm goes off, but he is not moving relative to source of sound, does the helmet wearer perceive a reduced velocity, frequency or wavelength or none? i remember reading that we are not sensitive to wavelength - only frequency - so maybe not wavelength; the only way frequency can change is through the doppler effect (someone correct me on this if im wrong), and if wavelength and freq do not change, neither will the velocity of the sound wave. but sound travels quicker in a helmet rather than air! at the same time, there is a gap of air between the helmet and our ears, so velocity should not change. so basically nothing changes and the person will hear the sound as if he is not wearing a helmet.

i hope my reasoning is correct, but if it is not, please let me know! thanks in advance!

 

[CodeBlu]

You'd be correct in assuming that we frequency code. The cochlea has a tonotopic representation. Frequency codes the APs down the 8th cranial nerve.

Still though, just because we perceive frequency, the wavelength and frequency are inversely proportional. You increase one, you decrease the other. The shorter the wavelength, the more crests and troughs move through and vibrate the cochlea at a higher frequency.

I hope this makes sense! Good luck.

 

[RocketSurgeon]

You'd be correct in assuming that we frequency code. The cochlea has a tonotopic representation. Frequency codes the APs down the 8th cranial nerve.

Still though, just because we perceive frequency, the wavelength and frequency are inversely proportional. You increase one, you decrease the other. The shorter the wavelength, the more crests and troughs move through and vibrate the cochlea at a higher frequency.

I hope this makes sense! Good luck.

The reason this is possible and the reason we can get so MANY patterns of sounds is that our ear can perform a Fourier analysis (remember any wave can be represented as a sum of sine and cosine waves)

also just having the frequencies of the original signal we can go from the Fourier frequency domain to spatial domain (Take a bunch of waves of different freq, add em up and get a signal)

Just a little neurobio engineering side note 👍