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Author Topic: Why can't I hear my pulse?  (Read 2184 times)

Offline thedoc

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Why can't I hear my pulse?
« on: 29/02/2012 16:19:53 »
We have blood vessels running right by our ears.  Why don't we hear our hearts beating or our pulse as it shusshes by our ear?
Asked by Joyce Roberts




                                        Visit the webpage for the podcast in which this question is answered.



 



« Last Edit: 29/02/2012 16:19:53 by _system »


 

Offline thedoc

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Why can't I hear my pulse?
« Reply #1 on: 29/02/2012 16:19:53 »
We answered this question on the show...







 Hannah -   The pulse, caused by the heartbeat, is strong in large arteries such as in your wrist, the traditional site for feeling the pulse, but as vessels branch out into smaller and smaller arterioles and eventually into capillaries, the pulse fades away and the blood flow becomes much smoother.  Scientists can see this in microscope images from small living blood vessels where the blood cells stream past like cars in a motorway with no evidence of pulsation.  There's very obvious pulsing in the ears because the blood is flowing through small vessels and the flow is smooth which is why you can't really hear the pulse in your ears.

Chris -   You've also got this effect when you put your head on the pillow and you create the occlusion effect because you have a closed environment against the ear which then reflects the sounds backwards and forwards, and amplifies them.  We did this as a Question of the Week:  Someone said, “Why is it when I put my earphones in to listen to the Naked Scientists podcast, that the sound of my breakfast cereal being crunched is much louder than when I don't have the earphones in even though I'm playing something else into my ears?  It’s because of this occlusion effect, you bounce the vibrations backwards and forwards off the two surfaces.

« Last Edit: 29/02/2012 16:19:53 by _system »
 

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Why can't I hear my pulse?
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