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The speed of sound...

post #1 of 7
9/11/11 at 7:55pm
Thread Starter 
I was helping my girlfriend's son study physics tonight and the topic was waves. He had a lot of questions on the speed of sound in different mediums and Doppler effect etc...

It just had me thinking and I wanted to sort of throw my thinking out and make sure it's "sound"....

No Doppler effect in headphones, everything is stationary.

The speed of those little sound waves can't be any different or changed by drivers... Once it is in the air in the headphone it's going to travel at the same speed in that medium, air.... Right? No driver can make them travel any faster or slower.

Just thinking out loud and looking for a sounding board. For once homework was interesting for me too! smily_headphones1.gif
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post #2 of 7
9/11/11 at 8:05pm

Umm, like you mean the sound waves are always going to travel at the same speed (obviously pressure/temp all the good stuff is constant) through the air? If so, yeah.

 

If you're getting at the head-fi term 'speed,' I've always thought that was an observation at how crisp and light attacks were.

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post #3 of 7
9/11/11 at 8:13pm
Thread Starter 

Definitely the first, the actual speed of the sound of waves... 340 m/s ish...

 

not the sonic description of speed or fast describing attacks and decay etc...

 

Thanks for thinking it through with me! 

 


 

Quote:
Originally Posted by logwed View Post

Umm, like you mean the sound waves are always going to travel at the same speed (obviously pressure/temp all the good stuff is constant) through the air? If so, yeah.

 

If you're getting at the head-fi term 'speed,' I've always thought that was an observation at how crisp and light attacks were.



 

 

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post #4 of 7
9/11/11 at 8:32pm

Since the speed of sound waves through air varies with pressure/humidity/temperature, all kinds of stuff, I've always wanted to see someone tweak their room to environmental perfection :p

 

"I find that an air temperature of 64.34 with a slight breeze offers the most lush sound!"

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post #5 of 7
9/11/11 at 8:48pm
Thread Starter 
Careful! I'm sure it's been done! tongue.gif

Or "I only listen at sea level". Could all those graphs from altitude in Colorado be flawed?

No real controversy with my post, just some very basic science.
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post #6 of 7
9/11/11 at 10:56pm
soundwaves from my understanding actually travels faster in humid conditions i believe. the warmer and more humid,faster the soundwave will travel but i don't think weather conditions really don't affect headphone enclosures and drivers too much. i can be wrong. i think the soundwave speed is always at a constant rate. i'm not very sure. i'm not very good at math much or never had a physics class before in my life.
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post #7 of 7
9/12/11 at 1:54pm

If you haven't looked it up you may be surprised by the relative magnitude of air pressure changes even at one location with ordinary weather systems, storm fronts, much less hurricanes

 

but sound velocity is relatively unchanged by human survivable air pressure differences - however loudspeaker box "tuning" will change to a degree that makes some marketing puffery about "0.1% XO component matching" stupidly silly

 

Doppler shift from moving the sound source does apply to audio transducers, fortunately headphone diaphragms don't have to move too far, too fast to generate high SPL so the distortion is imperceptible

 

loudspeaker systems, particularly single driver full range or bookshelf 2-ways where a small (say ~4.5") "long throw" woofer is used from 50 Hz to 2-3kHz can have audible Doppler distortion - although you may need to train with test signals to learn to recognize it


Edited by jcx - 9/12/11 at 1:55pm
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