What is Pitch - cgrahamphysics.files.wordpress.com€¦ · Key words 1/25/2016 Word Meaning...

What is Pitch Seeing Sound

1/25/2016 © cgrahamphysics.com 2016

Seeing Sound

Starter: ‘’In Space, no-one can hear you scream’’

Is this true? Explain your answer

How would astronauts communicate with each other without radio if they only had a hammer?


Aim

To identify the different parts of a sound wave;

To describe the relationship between volume and amplitude and frequency and pitch.


Key words

1/25/2016

Word Meaning

amplitude Half the height of a wave.

frequency The number of waves each second.

hertz (Hz) The unit for frequency. 1 hertz means one wave

per second.

loudness How loud a sound is; the volume of a sound.

oscilloscope An instrument which shows a picture of a wave

on a screen.

pitch How high or low a note sounds.

wave A way of transferring energy. Waves can be side

to side or backwards and forwards movements.

wavelength The distance between the top of one wave and

the top of the next. © cgrahamphysics.com 2016

Sound is a longitudinal wave

1/25/2016

What is a wave?

© cgrahamphysics.com 2016

Two Depictions of Sound Waves

rarefaction compression

= air particle

compressed

rarefied

Two depictions of sound waves...

amplitude

wavelength


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.

Oscilloscopes allow us to study frequency and loudness of a sound


How can I see sound?

A Rubens' tube, also known as a standing wave flame tube, or simply flame tube, is an antique physics apparatus for demonstrating acoustic standing waves in a tube.

Invented by German physicist Heinrich Rubens in 1905, it graphically shows the relationship between sound waves and sound pressure, like a primitive oscilloscope.

Rubens Tube Montage.mp4


Rubens Tube Montage.mp4

Changing Pitch and Volume

How can you change the pitch of an instrument?

How can you change the volume of a instrument?

BBC Sound - 02 - Movie Frequency and pitch.mpg










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 lower/higher the pitch

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

Pitch (or frequency)


Which trace represents the highest pitched sound?

A

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

Oscilloscope Traces

B


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 wave you can see, the louder the sound


Which trace represents the loudest sound?

‘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

A B


What can I hear?

Increase frequency of signal on the generator whilst keeping the volume the same.

The lowest frequency I can hear is ________ Hz

The highest frequency I can hear is ________ Hz

20

20 000

http://www.youtube.com/watch?v=RC8SV3L3bo0


Hearing Ranges

0 1 10 100

1,000

10,000

100,000

1,000,000

Frequency [Hz]

Moths

Elephants

Mice

Humans

Pigeons

Bats

Hearing Ranges of Animals

Which animal can hear the lowest frequency?

pigeons

Which animal can hear the highest frequency?

moths 1/25/2016 © cgrahamphysics.com 2016

• Number 1-11 in the front of your book

• When you hear the sound, write down what you think it is

11.

7.

3.

10. 9.

8. 6. 5.

4. 2. 1.

• Can you say whether the sound is loud or quiet, has a high or low pitch?

What Sound?

Challenge


Describing sound waves


Draw a high pitch sound

Draw a low pitch sound

Draw a loud pitch sound

Draw a quiet pitch sound

Draw a high pitch and loud sound

What does the sound look like?


Sound waves summary

Plenary


Plenary: 1) Explain to your partner the words below 2) Write a sentence about each word

Vibration

Pitch

Loud

Quiet

Hertz 1/25/2016 © cgrahamphysics.com 2016

Who will lose their cards first?

Sound Dominoes


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