© Boardworks Ltd 2003

What causes sound?

Take a tuning fork and strike it against a block of wood, what do you observe?

The tuning fork vibrates and you hear a sound.

All sounds are caused by vibrations.

© Boardworks Ltd 2003

Studying sound

Signal generators can produce signals over a range of frequencies and of varying amplitudes.

Loudspeakers convert the signal from the signal generator into sound waves.

The oscilloscope allows us to study the frequency and loudness of a sound.

© Boardworks Ltd 2003

Pitch (or frequency)

A high pitch sound. A low pitch sound.

The shorter/longer the wavelength of the wave on the trace; the lower/higher the frequency of the sound.

The more waves you can see, the higher the pitch/frequency.

© Boardworks Ltd 2003

Oscilloscope traces

Which trace represents the highest pitched sound?

A B

‘A’ is the highest pitched sound because it has the shortest wavelength/most number of waves visible.

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Loudness

A quiet sound. A louder sound.

The larger/smaller the amplitude of the wave on the trace, the louder/quieter the sound.

The bigger the waves you can see, the louder the sound.

© Boardworks Ltd 2003

Which trace represents the loudest sound?

A B

‘B’ Is the loudest sound because it has the largest amplitude.The larger the amplitude the more energy a wave has.The more energy it has, the louder the sound.

Oscilloscope traces

© Boardworks Ltd 2003

Wave animation