headharp

Head Harp

The String Section

Introduction

Wrap a string around your head and pluck it to play music. Hear how the frequency of vibration of a string depends on tension and length.

Material

A piece of string about an armspan long, 1.5 m.

To Do and Notice

Place the middle of the string behind your head, pull the string over your ears and hold the two free ends together in front of your face.

Pluck the strings.

Listen to the tone made by the string.

Pull the string tighter, or make it looser and listen to the change in pitch.

Change the length of the string while keeping the tension as constant as possible then listen to the change in pitch.

What's Going On?

When you pull the string tighter you increase the tension in the string and the pitch of the sound you hear increases.

When you keep the tension constant and decrease the length of the string the pitch increases.

You are hearing the resonant frequencies of a string.

The frequency is inversely proportional to the length of the string,

and proportional to the square root of the tension in the string.

You can hear your string, but the sounds produced by the string are so quiet you will not be disturbed by other people even if they are close to you.

Going Further

Two people can share this activity. Make a large loop of string and wrap it around two heads. Pluck the strings and play music for two.

Two Head Harp

Etc.

Many city bus services do not allow people to play loud music on the bus. We find that if you wrap a string around your head and play music not only will you not be in isolation of the city laws, but also other people on the bus will move away from you to give you more room.