Demonstrations

Speed of Sound in Air

Code Number :	3B30.10
Disclaimer:	Reprinted by permission of Dick Berg, University of Maryland, for use on this website. The demonstrations contained and referenced herein are listed for the purposes of cataloging and describing physics demonstrations which should be conducted only under the direction of a trained instructional support professional or physicist. These demonstrations are not presented for the purpose of being conducted by persons unconnected to this Facility and/or persons not consulting with or being supervised by the recognized instructional support professional or physicist and his/her staff. The University is responsible only for those demonstrations carried out using its own equipment using established safety and scheduling policies, and bears no responsibility for those choosing to use this source material for their own purposes. All demonstrations described and contained herein are public domain, and can also be found in reference materials in libraries, bookstores, and electronic sources. Further information regarding legal liability in use of demonstrations and labs will be found on the web site Injuries in School/College Laboratories in USA. The University of Iowa Disclaimers: University of Iowa Disclaimer All Rights Reserved..
Condition :	Good
Principle :	Wavelength of sound in air
Area of Study :	Acoustics
Equipment :	Oscilloscope, Wavetech Wave Generator, Speaker, Microphone with good battery, Preamp. (Stereo microphone mixer), 2 meter stick, Camera and Power Supply, laptop computer, SoftScope^TM module, 2 microphones, meter stick or rod, clicker.
Procedure :	Assemble the apparatus as shown. With the microphone in one channel and the wave generator in another you will get a measurable wave shift on the oscilloscope. From this you can directly measure the wavelength using the meter stick, and determine the speed by knowing the frequency as read on the digital wave generator or oscilloscope. The meter stick is used to measure the distance between the speaker and the microphone. Using higher frequencies ( 660 Hz, 990 Hz, etc. )you can cut out some of the background interferences as the microphone and speaker will be closer together for 1 complete shift of wavelength. The speed of sound can also be easily shown with the SoftScope^TM module, a laptop computer, and a couple of microphones. Usually we space the two microphones at 50 cm, and set the SoftScope for single trigger. Use the clicker to trigger and the measurements off the computer screen to calculate the speed of sound.

References

Wilton Pereira da Silva, Jurgen W. Precker, and Diogo D. P. S. e Silva, Cleiton D. P. S. e Silva, "The Speed of Sound in Air: An At-Home Experiment", TPT, Vol. 43, # 4, Apr. 2005, p. 219 - 221.

Marcelo M. F. Saba, Rafael Antonio da S. Rosa, "Measuring Distances with Walkie-Talkies", TPT, Vol. 43, # 4, Apr. 2005, p. 204 - 205.

Richard E. Berg and Dieter R. Bill, "Speed of Sound Using Lissajous Figures", TPT, Vol. 43, # 1, Jan. 2005, p. 36.

Inge H. A. Pettersen, "Speed of Sound in Gases Using an Ultrasonic Motion Detector", TPT, Vol. 40, # 5, May 2002, p. 284.

Rand S. Worland and D. David Wilson, "The Speed of Sound in Air as a Function of Temperature," TPT, Vol. 37, # 1, p. 53, (Jan. 1999).

James E. Kettler, "Whistlin' Dixie and the Speed of Sound," TPT, Vol. 35, # 8, p. 469, (Nov. 1997).

Richard Gagne, "Determining the Speed of Sound Using the Doppler Effect," TPT, Vol. 34, # 2, p. 126-127, (Feb. 1996).

Loren M. Winters, "A Visual Measurement of the Speed of Sound", TPT, Vol. 31, # 5, May 1993, p. 284.

Geodge W. Ficken Jr., "Better Than We Thought", TPT, Vol. 28, # 9, Dec. 1990, p. 580.

Judish Bransky, "Measurements of Sound Velocity by Means of PZT", TPT, Vol. 28, # 2, Feb. 1990, p. 125.

Jan Paul Dabrowski, "Speed of Sound in a Parking Lot," TPT, Vol. 28, # 6, p. 410, (September 1990).

George Biehl, "Measuring the Speed of Sound", TPT, Vol. 27, # 3, Mar. 1989, p. 172.

"Experiments with Sharp Acoustical Pulses", TPT, Vol. 25, # 3, Mar. 1987, p. 167.

"Errata", TPT, Vol. 25, # 9, Dec. 1987, p. 546.

John E. Girard, "Direct Measurement of the Speed of Sound", TPT, Vol. 17, # 6, Sept. 1979, p. 393.

Thomas B. Greenslade, Jr., "The Speed of Sound in Air", TPT, Vol. 15, # 4. Apr. 1977, p. 240.

Russel C. Hansen, "High Precision Method of Measuring the Velocity of Sound with Simple Apparatus", TPT, Vol. 13, # 2, Feb. 1975, p. 101.

G. T. Hageseth and R. B. Muir, "Pulsed and Traveling Sound Waves in the Introductory Physics Laboratory", TPT, Vol. 12, # 2, Feb. 1974, p. 99.

Walter Kruschwitz, "A Demonstration of the Dependence of Temperature and Medium on the Speed of Sound", TPT, Vol. 11, # 1, Jan. 1973, p. 47.

Herbert H. Gottlieb, "Velocity of Sound Using an Oscilloscope", TPT, Vol. 5, # 4, April 1967, p. 173.

E. U. Condon, "Note the Velocity of Sound", TPT, Vol. 3, # 2, Feb. 1965, p. 80.

Edward M. Lttle, "Too Slow to be Isothermal?", TPT, Vol. 3, # 2, Feb. 1965, p. 80.

Francis W. Sears, "Measurement of the Wavelength of Sound Waves", TPT, Vol. 3, # 2, Feb. 1965, p. 79.

Jon P. Vickery, "Determination of the Velocity of the Sound in Air", TPT, Vol. 3, # 4, April 1965, p. 170.

F. E. Christensen, "Determination of the Velocity of Sound in Air", TPT, Vol. 2, # 8, Nov. 1964, p. 390

S. Velasco, F. L. Roman, A. Gonzalez, and J. A. White, "A Computer - Assisted Experiment for the Measurement of the Temperature Dependence of the Speed of Sound in Air", AJP, Vol. 72, # 2, Feb. 2004, p. 276.

S. J. S. Morris, "Sound Speed Without Entropy", AJP, Vol. 70, # 5, May 2002, p. 495.

Sh - 1: Freier and Anderson, A Demonstration Handbook for Physics.

W- 080: "Two Speakers on Optical Bench," DICK and RAE Physics Demo Notebook.

"Speed of Sound in a Snap", The Caliper, Vernier Software Technology, Spring 2007.

Francis W. Sears, "Measurement of the Wavelength of Sound Waves," Apparatus for Teaching Physics, p. 52.

"How Did They Measure the Speed of Sound?" Reader's Digest How in the World, p. 201.

James Cunningham and Norman Herr, 6.3, Hands-On Physics Activities with Real-Life Applications.

Robert Ehrlich, "Speed of Sound," Why Toast Lands Jelly-Side Down, p. 138 - 139.

Ron Hipschman, "Echo Tube," Exploratorium Cookbook II, p. 114.1 - 114.4.

Mail Questions and Comments to: Dale Stille