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23
votes
3answers
3k views

Can humans perceive sounds above 20 kHz?

In the never-ending debate raging in the audiophile community about sound quality and what humans can or cannot hear, it is very very very very incredibly often cited that the upper-limit of the ...
7
votes
3answers
120 views

Are there echolocating insects?

Echolocation is the ability to obtain spatial information of the surroundings from echos generated by the animal. There are bats and other vertebrates that naturally use it. I was wondering if this ...
1
vote
1answer
68 views

Are there any bacteria that can receive ultrasound signals?

I'm looking for an example of bacteria that could receive ultrasound (at any ultrasound frequency) signal and possibly perform some (re)action afterwards.
2
votes
2answers
45 views

Can stress echocardiography show coronary blood flow difference before and after exercise?

Stress echocardiography means a pair of cardiac ultrasound imaging examinations, before and after exercise. I assume that coronary blood flow is increased after exercise. Is cardiac ultrasound ...
3
votes
1answer
78 views

Can frequent ultrasound diagnostics be harmful?

Are there any short or long term effects apparent in tissues if a zone (or the whole) of human body is scanned with ultrasonic waves often?