Subject: Re: The next wave From: Mike Ravicz <mer(at)EPL.MEEI.HARVARD.EDU> Date: Fri, 3 Aug 2001 09:57:50 -0400>what is the >highest >frequency that >sound can >have? I'll take a stab at it... As usual, the answer to such a question is, "It depends" - what did you have in mind when you referred to "sound"? The highest frequency you can hear? The highest frequency anyone can hear (~20 kHz)? The highest frequency any creature can hear in air (~120 kHz)? The highest frequency any creature can hear in water (~180-220 kHz)? The highest frequency at which vibrations can be transmitted through air (~10 GHz)? through water? The highest frequency anything can vibrate (10 THz, according to the Dictionary of Acoustics)? Ultrasonic refers to sound at frequencies higher than can be heard by an average young person, but in my experience, people usually use it refer to frequencies higher than about 50 kHz. Frequencies too high to propagate (e.g., 10 GHz in air) are referred to as hypersonic (Dictionary of Acoustics again). Why do you ask? - Mike Ravicz