Does Ultrasound Affect Hearing?

[Guest guest]

A little bit ago, someone, I think Jane, asked if the electronic mouse

repellers are bad for you. Didn't know, but thought I'd look and see what

came up. While I couldn't find anything specifically on whether or not

the electronic mouse repellers affect you, I did find some interesting

information on ultrasonic waves. Unfortunatley, it seemed as if the more

I read, the more complex the issue. The long and the short of it -

no one really knows (or is telling) at this point, but they think

something with is low frequency ultrasound doesn't affect

people.

It appears, however, that certain frequencies affect people more than

others. And, on the whole, the lower frequencies of the mouse and bug

repellers aren't supposed to. However, what little I was able to find

out, didn't just jump out. I went to a number of different sources and

found some interesting things out, but not what I was looking for. I

focused on hearing issues - perhaps I should have broadened my search.

One other thing - there may be research not readily accessible to me

regarding affects of ultrasound in various frequencies on people. Some

places make you pay before you read whatever study they have. You can

read the abstract, but that doesn't always tell you what you want to

know. Other sites require a password or something like that. They don't

let just anyone in.

But, I'll share with you what I have found out thus far.

Ultrasound is high-frequency (even what's called low frequency

ultrasound) and can not be heard by the human ear - in most cases. Turns

out that some people can hear some frequencies others can't. and,

teenagers and kids can hear certain frequencies adults no longer can.

However, even though we can't usually hear ultrasound, according

to OSHA (Dept. of Labor, Occupational and Safety & Health

Administration), it " may still affect hearing and produce other side

effects. "

Factors to consider regarding ultrasonics include:

The upper frequency of audibility of the human ear is approximately

15-20 kilo-Hertz (kHz).

This is not a set limit and some individuals may have higher or lower

(usually lower) limits. The frequency limit normally declines with age.

Most of the audible noise associated with ultrasonic sources, such as

ultrasonic welders or ultrasonic cleaners, consists of subharmonics of

the machine's major ultrasonic frequencies.

Example: Many ultrasonic welders have a fundamental operating

frequency of 20 kHz, a sound that is at the upper frequency of audibility

of the human ear. However, a good deal of noise may be present at 10 kHz,

the first subharmonic frequency of the 20 kHz operating frequency, and is

therefore audible to most persons. (From

 

http://www.osha.gov/dts/osta/otm/noise/health_effects/index.html)

 

What's called low frequency ultrasound goes up to approximately to

500 kHz. A sonogram typically operates at several hundred kilohertz. Research is being done using low frequency ultra sound for chronic

wounds. Those machines are measured in the tens of kilohertz.

 

http://medgadget.com/archives/2007/12/lowfrequency_ultrasound_for_chronic_wounds.html

 

Apparently, work is being done using high audio frequencies and

low frequency ultrasound to mask tinnitus.

 

http://www.tinnitus.vcu.edu/Pages/Ultrasonic%20Hearing.pdf

 

You know the tools in the dentist's office that use ultrasound? Well,

there was study done on the " Effects of Occupational Ultrasound

Noise Exposure on Hearing in Dental Hygienists "

 

http://www.ncbi.nlm.nih.gov/pubmed/12592917?ordinalpos=1 & itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DiscoveryPanel.Pubmed_Discovery_RA

 

While, for the most part, the study indicated that the tools don't affect

one's hearing, it was interesting to see that certain frequencies may

have a deleterious effect on hearing and could potentially cause hearing

loss - 3000 Hz. The scaler at 500, 1000, 2000, 4000, 6000 and 8000 Hz

had no effect on hearing, but, they concluded 3000 Hz may affect the

hearing. Curious how neither below that figure, nor above it had any

recordable impact on hearing.

I can't remember where I saw it, and can't seem to locate it right now,

but in one of the articles re: ultrasound and hearing, it spoke

about how certain frequencies were transmitted by bone, whereas the

higher frequencies (really high) were transmitted by fluid. I wondered if

really high frequencies affected us in some way, not yet discernable.

From a site that gives guidelines for the Safe Use of Ultrasound. "

Nonetheless, although reports of biological effects are

surprisingly rare, exposure to the liquid-borne ultrasound from these

devices clearly can cause tissue injury, and protection measures are

necessary. "

 

http://www.hc-sc.gc.ca/ewh-semt/pubs/radiation/safety-code_24-securite/health-sante_e.html

 

I didn't realize some of the odor sprayers to control moths also

use Ultrasound.

 

http://www.springerlink.com/content/w65283r7522w1010/

I also didn't realize that ultrasound is used in a number of surgical

applications, including liposuction.

 

http://www.misonix.com/medical This site also has an

interesting graph.

Interesting that someone also came up with an " anti-teen "

device, which emits tones only younger folks can hear. They've installed

it in many places in the UK where teens congregated.

 

http://www.timesonline.co.uk/tol/news/uk/article3356157.ece

One of the things that struck me, is how often ultrasound is being used

today - with more applications on the way. I had no idea.....

Lynn