1601 Sound Waves

Exercises

16.5 BIO Ultrasound and Infrasound. (a) Whale communication. Blue whales apparently communicate with each other using sound of frequency $17$ Hz, which can be heard nearly $1000$ km away in the ocean. What is the wavelength of such a sound in seawater, where the speed of sound is $1531$ m/s? (b) Dolphin clicks. One type of sound that dolphins emit is a sharp click of wavelength $1.5$ cm in the ocean. What is the frequency of such clicks? (c) Dog whistles. One brand of dog whistles claims a frequency of $25$ kHz for its product. What is the wavelength of this sound? (d) Bats. While bats emit a wide variety of sounds, one type emits pulses of sound having a frequency between $39$ kHz and $78$ kHz. What is the range of wavelengths of this sound? (e) Sonograms. Ultrasound is used to view the interior of the body, much as x rays are utilized. For sharp imagery, the wavelength of the sound should be around one-fourth (or less) the size of the objects to be viewed. Approximately what frequency of sound is needed to produce a clear image of a tumor that is 1.0 mm across if the speed of sound in the tissue is $1550$ m/s?