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- ''For other meanings of "ultrasound" or "ultrasonic", see ultrasound (disambiguation).
Ultrasound is sound with a frequency greater than the upper limit of human hearing, this limit being approximately 20 kilohertz (20,000 hertz).
Ability to hear ultrasound
Some animals, such as dogs, dolphins, bats, and mice have an upper limit that is greater than that of the human ear and thus can hear ultrasound. Children can hear some high-pitched sounds that older adults cannot hear, as in humans the upper limit pitch of hearing gets lower with age. This frequency limit is caused by the middle ear that acts as a low-pass filter. If ultrasound is fed directly into the skull bone and reaches the cochlea without passing through the middle ear, much higher frequencies (up to about 200 kHz) can be heard. This effect (sometimes called ultrasonic hearing) was first discovered by divers exposed to a high-frequency (ca. 50 kHz) sonar signal.Medical sonography
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U - Twitter Search
RT @GetDoe_Joe: Where's my brutha @StayRich_Chris ? Yeerrr<----Sup Son? I'm headed 2 the Knicks Game now homie wish u was in N.Y!
StayRich_Chris (LIVE-RICH) Fri, 06 Nov 2009 23:36:00 -0000
RT @GetDoe_Joe: Where's my brutha @StayRich_Chris ? Yeerrr<----Sup Son? I'm headed 2 the Knicks Game now homie wish u was in N.Y!
i'm hoping that ur mama don't mind, cuz girl i gotta make u mine (:
leonardogleme (Leonardo Leme) Fri, 06 Nov 2009 23:36:00 -0000
i'm hoping that ur mama don't mind, cuz girl i gotta make u mine (:
@keenahbahd0x r u watchin da new sponge bob show "truth or square" tonight? lol
LiLFlockaSODMG (â ââ â.â¢âιâ ŦÑεâ¢.â â ââ ) Fri, 06 Nov 2009 23:36:00 -0000
@keenahbahd0x r u watchin da new sponge bob show "truth or square" tonight? lol
#followfriday @itsmeAmerie @JasmineTame @AnditisLiz @BangBroProducer @simmywilson @Miss_Emichi @JOiisey @therealJuliaAnn R U FOLLOWING US!!!
icandysensation (EyeCandy Sensation) Fri, 06 Nov 2009 23:36:00 -0000
#followfriday @itsmeAmerie @JasmineTame @AnditisLiz @BangBroProducer @simmywilson @Miss_Emichi @JOiisey @therealJuliaAnn R U FOLLOWING US!!!
@ITSDOE Thanx my man!...U still out here?
bmacthequeen (Britney Mac) Fri, 06 Nov 2009 23:36:00 -0000
@ITSDOE Thanx my man!...U still out here?
@brian_littrell This is YOUR peru-wars T-shirt I bought it 4 you http://tweetphoto.com/98fca I know u love SW! with all my heart 4 u :-)
carlahbsb (carla fernandez) Fri, 06 Nov 2009 23:36:00 -0000
@brian_littrell This is YOUR peru-wars T-shirt I bought it 4 you http://tweetphoto.com/98fca I know u love SW! with all my heart 4 u :-)
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RT @GetDoe_Joe: Where's my brutha @StayRich_Chris ? Yeerrr<----Sup Son? I'm headed 2 the Knicks Game now homie wish u was in N.Y!
StayRich_Chris (LIVE-RICH) Fri, 06 Nov 2009 23:36:00 -0000
RT @GetDoe_Joe: Where's my brutha @StayRich_Chris ? Yeerrr<----Sup Son? I'm headed 2 the Knicks Game now homie wish u was in N.Y!
i'm hoping that ur mama don't mind, cuz girl i gotta make u mine (:
leonardogleme (Leonardo Leme) Fri, 06 Nov 2009 23:36:00 -0000
i'm hoping that ur mama don't mind, cuz girl i gotta make u mine (:
@keenahbahd0x r u watchin da new sponge bob show "truth or square" tonight? lol
LiLFlockaSODMG (â ââ â.â¢âιâ ŦÑεâ¢.â â ââ ) Fri, 06 Nov 2009 23:36:00 -0000
@keenahbahd0x r u watchin da new sponge bob show "truth or square" tonight? lol
#followfriday @itsmeAmerie @JasmineTame @AnditisLiz @BangBroProducer @simmywilson @Miss_Emichi @JOiisey @therealJuliaAnn R U FOLLOWING US!!!
icandysensation (EyeCandy Sensation) Fri, 06 Nov 2009 23:36:00 -0000
#followfriday @itsmeAmerie @JasmineTame @AnditisLiz @BangBroProducer @simmywilson @Miss_Emichi @JOiisey @therealJuliaAnn R U FOLLOWING US!!!
@ITSDOE Thanx my man!...U still out here?
bmacthequeen (Britney Mac) Fri, 06 Nov 2009 23:36:00 -0000
@ITSDOE Thanx my man!...U still out here?
@brian_littrell This is YOUR peru-wars T-shirt I bought it 4 you http://tweetphoto.com/98fca I know u love SW! with all my heart 4 u :-)
carlahbsb (carla fernandez) Fri, 06 Nov 2009 23:36:00 -0000
@brian_littrell This is YOUR peru-wars T-shirt I bought it 4 you http://tweetphoto.com/98fca I know u love SW! with all my heart 4 u :-)
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