Sound and Acoustics

Change pitch of organ pipes by changing sound velocity.

What it shows:

At a constant temperature, the speed of sound in a gas c, is dependant on the molecular weight of the medium

Run towards the blackboard carrying a tuning fork...

What it shows:

Waves emitted from a moving source are Doppler shifted to higher frequencies when moving towards the observer, and shifted to lower frequencies when moving away from the observer. In this...

A high-pitched alarm on the end of a rope is whirled about the head.

What it shows:

Doppler shift of sound emitted by an object moving in a circular orbit, with the pitch clearly changing as the object move towards, away or perpendicular to the line of the...

Two speakers, one at each end of rotating platform; beating due to frequency shift of speakers travelling in opposite directions.

What it shows:

Doppler shifting of sound to higher frequencies occurs when a source is moving towards the observer, and shifted...

Plastic Wiffle Ball with built-in shriek to throw past (or at) your audience.

What it shows:

Waves emitted from a moving source are Doppler shifted to higher frequencies when moving toward the observer, and shifted to lower frequencies when moving away...

A bell, ringing in a bell jar, ceases to be heard as the bell jar is evacuated.

What it shows:

As a passive amplification device, the exponential horn is amazing. Using a "talking" greeting card as a feeble source of music, the intensity of the sound gets amplified by about 18 dB when the greeting card is coupled to the horn ... a...

Sound pressure level of a fire bell decreases by 6dB when distance is doubled.

What It Shows

The intensity of sound waves emanating from a point source changes inversely as the square of the distance from the source (for an example using visible light...

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.

What It Shows

Due to an impedance mismatch, a sound pressure pulse traveling down the length of a pipe suffers a...

Balloons filled with helium, CO₂, or SF₆ act as diverging and converging lenses, respectively.

What it shows:

A balloon, filled with a gas different from air, will refract sound waves. A gas denser than air turns the balloon into a converging lens and a...