Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: mriver8 on 29/09/2014 06:45:05

Title: What type of headwear, and material could protect the head from an ultrasound?
Post by: mriver8 on 29/09/2014 06:45:05
assault at a freq capable of destroying hair cells? The best I've tried is Grainger closed cell polyurethane foam but it only protects against a numbing tuning fork sensation, and not concentrated/focused zaps.

https://dl-web.dropbox.com/get/127436857-Acoustic-Weapons-A-Prospective-Assessment-Jurgen-Altmann-1.pdf?_subject_uid=317902351&w=AABRd95PNFTrgeib-gQ1M95B9qc9u_wsJkZwk0m_xqaDxg
Title: Re: What type of headwear, and material could protect the head from an ultrasound?
Post by: chiralSPO on 29/09/2014 18:16:58
Just surround your head with a total vacuum. [;)] No sound will penetrate.
Title: Re: What type of headwear, and material could protect the head from an ultrasound?
Post by: alancalverd on 29/09/2014 19:11:24
Ultrasound is reflected at interfaces of materials with widely differing speed of sound. Sound travels through steel at 2 to 3 times the speed in water or soft brain tissue, so the traditional nutter's helmet (a salad colander) on top of a wooly hat will provide adequate protection with good ventilation, but for total security you could wear several layers, say an aviator's leather helmet under a motorbike lid, topped off with a naval anti-flash balaclava and a coal scuttle/Ned Kelly armour.   
Title: Re: What type of headwear, and material could protect the head from an ultrasound?
Post by: Bill S on 29/09/2014 19:58:33
I tried following the above link and got a message saying I didn't belong there.  Imagine my relief!!
Title: Re: What type of headwear, and material could protect the head from an ultrasound?
Post by: jeffreyH on 29/09/2014 21:13:29
Ultrasound is reflected at interfaces of materials with widely differing speed of sound. Sound travels through steel at 2 to 3 times the speed in water or soft brain tissue, so the traditional nutter's helmet (a salad colander) on top of a wooly hat will provide adequate protection with good ventilation, but for total security you could wear several layers, say an aviator's leather helmet under a motorbike lid, topped off with a naval anti-flash balaclava and a coal scuttle/Ned Kelly armour.

Now I'm tired and in hysterics.
Title: Re: What type of headwear, and material could protect the head from an ultrasound?
Post by: mriver8 on 29/09/2014 23:11:48
Ultrasound is reflected at interfaces of materials with widely differing speed of sound. Sound travels through steel at 2 to 3 times the speed in water or soft brain tissue, so the traditional nutter's helmet (a salad colander) on top of a wooly hat will provide adequate protection with good ventilation, but for total security you could wear several layers, say an aviator's leather helmet under a motorbike lid, topped off with a naval anti-flash balaclava and a coal scuttle/Ned Kelly armour.

Now I'm tired and in hysterics.
Title: Re: What type of headwear, and material could protect the head from an ultrasound?
Post by: mriver8 on 29/09/2014 23:14:31
I tried following the above link and got a message saying I didn't belong there.  Imagine my relief!!


See attachment. At these frequencies.
Title: Re: What type of headwear, and material could protect the head from an ultrasound?
Post by: chiralSPO on 29/09/2014 23:27:27
From the second image you posted, it is clear that this is not ultrasound being discussed, but very loud blasts, similar to concussions from bombs or shells. The first image is about high frequencies though...