Could someone give me the simple Straight Dope on this. What the heck is it. What effect does it have. What dangers, if any, does it pose in the brains of humans. I was looking up some info and found a short sentence on dolphins capable of causing cavitation with their ecolocation. And that there have been noticed effects in people after have contact with dolphins.more retarded) soon??
astro
October 10, 2004, 11:40pm
2
It’s basically talking about the effects of powerful utrasound impulses. Ultrasound can cause hazardous effects if powerful enough, mainly through heat generation and possibly cell disruption. Whether a dolphins echo location and ultrasonic communication output is powerful enough to cause these effects is unknown to me.
Here’s a page about it
Fundamentals
Sonochemistry is the application of ultrasound to chemical reactions and processes. Ultrasound is the part of the sonic spectrum which ranges from about 20 kHz to 10 MHz and can be roughly subdivided in three main regions: low frequency, high power ultrasound (20-100 kHz), high frequency, medium power ultrasound (100 kHz-1 MHz), and high frequency, low power ultrasound (1-10 MHz). The range from 20 kHz to around 1 MHz is used in sonochemistry wheras frequencies far above 1 MHz are used as medical and diagnostic ultrasound.
The origin of sonochemical effects in liquids is the phenomenon of acoustic cavitation. The term cavitation comes from the latin word cavus = cavity. Acoustical energy is mechanical energy i.e. it is not absorbed by molecules. Ultrasound is transmitted through a medium via pressure waves by inducing vibrational motion of the molecules which alternately compress and stretch the molecular structure of the medium due to a time-varying pressure. Therefore, the distance among the molecules vary as the molecules oscillate around their mean position. If the intensity of ultrasound in a liquid is increased, a point is reached at which the intramolecular forces are not able to hold the molecular structure intact. Consequently, it breaks down and a cavity is formed. This cavity is called cavitation bubble as this process is called cavitation and the point where it starts cavitation threshold. A bubble responds to the sound field in the liquid by expanding and contracting, i.e. it is excited by a time-varying pressure.Two forms of cavitation are known: stable and transient. Stable cavitation means that the bubbles oscillate around their equilibrium position over several refraction/compression cycles. While transient cavitation, the bubbles grow over one (sometimes two or three) acoustic cycles to double their initial size and finally collapse violently.
Ultrasound in Life Sciences and Medicine
Firstly, applications without any destruction or damage on living tissues :
Secondly, ultrasound caused damage on living tissues :
Thirdly, sonochemical preparation of biomaterials
(bolding mine)
Thank goodness I have so many, right?
Wait! That sounds like a good thing.