Unit 3 – Pitch
Activity 1 – Sound
The Teacher is encouraged to discuss the following points with the students:
- Sound occurs when something vibrates.
- Vibrating objects make sound. This sound is picked up by our ears and hence we are able to hear it.
- We hear sound when the vibrating air hits our ear drums.
- Sounds travels through air or other material such as stone, water, glass and brick.
- Sound cannot travel through a vacuum because there is nothing to vibrate.
- The more energy in the vibration – the louder the sound i.e. the harder you hit something the louder the sound.
- Pitch is how high or low a note is.
- The shorter the vibrating object, the higher the pitch of the note.
- The tighter the string, the higher the pitch of the note.
Activity 2 – Sound Insulation
Some materials allow sound pass through them very easily.
These are usually hard materials, such as metal.
Other materials, absorb sound.
These are usually soft materials , such as cotton.
In this activity we will investigate which materials one should use to make ear protectors.
Activity 3 – Vibrations, frequency and pitch
The number of vibrations per second is called the frequency.
Faster vibrations means a higher frequency and therefore a higher pitch.
We can change the pitch of a vibrating string by changing its length.
A longer string makes a low pitched note, because the frequency is lower.
Activity 4 – Tube length
Woodwind instruments include instruments with various tube sizes. Pitch changes according to the length of the tube.
Piccolo: short sized tube – high pitched notes
Clarinet: medium sized tube – medium pitched notes
Bassoon: long sized tube – low pitched notes
In a short tube, sound waves travel faster. Fast vibrations produce a high-pitched note.
In a longer tube, sound waves travel slower. Slow vibrations produce a low-pitched note.
In the activity below, building a pan flute, we will explore how different notes are produced when blowing through tubes of different lengths.