Good Vibrations
We’re surrounded by sound and our ears are bombarded by noise but do you know how sound is made and how it travels? It’s all to do with vibrations of course. Experiment with odd musical instruments, find out how your vocal cords work, puzzle your brain with sound illusions and watch your voice on a computer screen.
Exhibition requirements

• A gallery with about 100 sq metres of open floor space.
• Electrical power – ten plug sockets.
• The exhibition must be supervised at all times when in use, preferably by staff accustomed to working in an interactive environment.

Exhibit list

Vibrating string – A vertical string is linked to a loudspeaker. As you adjust the frequency of the sound the string shows harmonics as standing waves. The wavelengths of different notes can then be seen.
Vibrating bowl – The water in this Chinese brass bowl vibrates and leaps up in a spray when the handles are gently rubbed.
Pressure wave – Push a knob to send a pressure wave down a slinky spring – this is similar to the way sound travels in air.
Speech stretcher – An electronic device stores your message and reproduces it at different speeds – compressing or stretching the sounds.
Delay phone – Speak into a microphone connected to an electronic circuit which plays back your voice after a short delay. Most people find it impossible to continue speaking.
Light lyre – Instead of strings this lyre has infrared light beams which, when plucked, produce the notes.
Bucket radio – A radio with a small metal peg instead of a speaker can barely be heard. The sound is dramatically increased when the visitor places a bucket on the peg.
Speech patterns – Speak into a microphone and see the pattern of your voice on a computer screen.
Theramin – This was the first music synthesiser to be invented. Play a tune by waving your hands close to two aerials.
Hearing tester – Find out how high a frequency you can hear. Shown with giant model of an ear.
Artificial vocal cords – This instrument is normally used by people who have had their vocal cords removed but it helps visitors understand how speech is made. Shown with giant model of larynx.
Ear clangers – A metal grille is suspended from wires attached to headphones. Tap the grilles to hear how well sound travels through metal.
Phone a friend – Speak to a friend through a long tube. This shows how well sound travels round corners.
Sound or music? – Try playing two wooden drums, one solid and one hollow, and also two glockenspiels, one with the bars damped, to investigate how musical sounds are made.
Tea chest bass – Try playing this traditional instrument.
Sound illusion – This illusion tricks your brain as the sound appears to go higher and higher endlessly.