Sounds on a Screen

Sounds on a Screen

Grade 7

Open Ended

Who might use a microphone in their work? What would they use it for?

Sounds on a screen

A sound wave is a vibration travelling through the air, or through another material. We cannot see sound wave.

A microphone can detect sound waves. It changes them into electrical vibrations.

Seeing a trace

• If you connect a microphone to an oscilloscope.

• Oscilloscope allows you to see a picture of the sound wave on the screen.

• The line is called trace.

Changing amplitude

• With a loud sound, the trace goes up and down and down much more. Its amplitude is greater.

• With a quiet sound, the trace goes up and down a bit in the shave of wave. It has a small of the amplitude.

• When there is no sound, the trace is a flat line. The air molecules are not vibrating.

Changing pitch

• For high pitched sound, the waves shown by the trace are closer together.

• For a low pitched sound, the waves are more spread out.

Multiple Choice

The waves shown by the trace are closer together. The molecules of the air are vibrating more times each second.

• Higher pitch

• lower pitch

• Quiet sound

• Loud sound

Multiple Choice

The waves shown are more spread out.

• Higher pitch

• lower pitch

• Quiet sound

• Loud sound

Multiple Choice

the trace goes up and down much more. Its amplitude is greater.

• Higher pitch

• lower pitch

• Quiet sound

• Loud sound

Multiple Choice

The race goes up abd down a bit in the shape of a wave.

• Higher pitch

• lower pitch

• Quiet sound

• Loud sound

Multiple Choice

The trace is a flat line. The air molecules are not vibrating.

• Quiet sound

• Loud sound

• Silence

• Low pitched sound

Multiple Choice

Which end of the scale (left or right) has the loudest sounds?

• left- hand end

• right-hand end

Multiple Choice

Which is louder, a car or a motorbike?

• car

• motorbike

Multiple Choice

According to the diagram, what is the loudness of a television

• 80dB

• 70dB

• 60dB

• 10dB

Open Ended

Loud songs can damage your hearing. Could a crying baby cause damage? Explain how can you tell from the diagram.