Naked Science Forum

General Science => General Science => Topic started by: brstamper on 13/05/2008 01:42:16

Title: can you hear a 25,000Hz sound?
Post by: brstamper on 13/05/2008 01:42:16
Can you hear a 25,000Hz sound?
Title: can you hear a 25,000Hz sound?
Post by: chris on 13/05/2008 08:28:23
Almost certainly not. The threshold of human hearing, even amongst the youngest, keenest ears, is about 20kHz (20,000Hz). 25,000Hz is into the ultrasound that echo-locating insectivorous bats use!

An interesting piece of research was published in PLoS One recently, looking at bat sounds:

http://www.thenakedscientists.com/HTML/content/news/news/1369/

Chris
Title: can you hear a 25,000Hz sound?
Post by: lyner on 13/05/2008 11:17:30
It may be possible to hear the beat between a 25kHz tone and some other sound, though.  It's a sort of cheat method - not direct hearing. There are people who seem to be able to detect the presence or absence of ultra sonic sampling frequencies  in critical digital audio tests when they 'shouldn't'.  Again, it may be other 'clues' they are using.
They must be very young, tho'. Cloth ears develop very soon in your life. Mine are very clothy - pardon?
Title: can you hear a 25,000Hz sound?
Post by: RD on 13/05/2008 16:02:45
Quote
Ultrasonic Hearing in Humans: Applications for Tinnitus Treatment
Martin L. Lenhardt, Au.D., Ph.D. Professor
Departments of Otolaryngology and Emergency Medicine, Virginia Commonwealth
University, Richmond, VA
International Tinnitus Journal, Vol. 9, No. 2, 2003


Humans can detect ultrasound up to at least 100 kHz, but perception generally requires
direct contact of the source with the body
. Ultrasound sets the brain into forced vibration,
and it is the brain oscillation that is detected on the base of the cochlea in normally
hearing individuals.
http://www.tinnitus.vcu.edu/Pages/Ultrasonic%20Hearing.pdf

So yes it is possible to "hear" ultrasound, but it has to be powerful enough to rattle your brain.
Title: can you hear a 25,000Hz sound?
Post by: chris on 13/05/2008 18:42:15
I'm not sure this qualifies as hearing though does it?

If you go to a loud rock concert and experience the base predominantly in your belly as visceral vibrations, are you still "hearing it"?

Interesting reference though - I shall read it.

Chris