Velocity of Sound
[M | t+ | —]
Velocity of sound is determined by measurement of the time delay of pressure pulse detected by a microphone and its distance from the loudspeaker.
Sound Cancellation
[M | t+ | ★★★]
Feed the same signal to two speakers and reverse the connections to one of them. Result: sound cancellation!
Double Sound Source Interference
[M | t+ | ★★★]
Young's experiment performed with coherent sound waves from two loudspeakers.
Refraction of Sound
[M | t+ | ★★★]
Balloons filled with helium, CO2, or SF6 act as diverging and converging lenses, respectively.
Sound Reflections in Pipes
[L | t++ | ★★★]
A pulse of sound gets "inverted" when reflecting off the open end of a pipe, but does not get inverted when reflecting off the closed end.
Inverse Square Intensity
[M | t+ | ★★★]
Sound pressure level of a fire bell decreases by 6dB when distance is doubled.
Acoustic Horn
[M | t+ | —]
A multicellular horn is shown to amplify sound by 18 dB.
No Sound Through a Vacuum
[L | t+ | ★★]
A bell, ringing in a bell jar, ceases to be heard as the bell jar is evacuated.
Doppler Ball
[S | t | ★★★]
Plastic Wiffle Ball with built-in shriek to throw past (or at) your audience.
[In-Depth Description]
Doppler Turntable
[L | t+ | ★★]
Two speakers, one at each end of rotating platform; beating due to frequency shift of speakers travelling in opposite directions.
[In-Depth Description]
Doppler Whirler
[M | t | ★★★]
A high-pitched alarm on the end of a rope is whirled about the head.
[In-Depth Description]
Doppler Tuning Forks
[M | t | ★★]
Run towards the blackboard carrying a tuning fork...
[In-Depth Description]
Sound Waves in a Room
[L | t+ | —]
Three dimensional standing waves are generated in the lecture hall and detected by students moving about.
Helium and Sulfur Hexafluoride
[M | t | ★★★]
Change pitch of organ pipes by changing sound velocity.
Baffle
[M | t | ★★★]
Placing a baffle behind a tuning fork (or small louspeaker) dramatically increases the intensity of the sound.
Contact Us
Mailing Address: Lecture Demonstration Services, Science Center, Rm B-08A, 1 Oxford Street, Cambridge, MA 02138
Campus Location: Science Center B-08A | Tel: (617) 495-5824 | Email: scidemos-at-fas.harvard.edu