Building Science Concepts: Exploring sound

Use music to engage students in learning the science concepts of sound in a fun and meaningful way.

The New Zealand Ministry of Education’s Building Science Concepts (BSC) series presents sets of interlinking concepts that build stage by stage towards big ideas in science. A big idea shows how a fully developed understanding of the concept might look, but recognises that such an understanding might not be achieved until New Zealand Curriculum level 7 or 8.

This resource is a partial replication of Building Science Concepts Book 18 Exploring Sound: Using Sound-makers and Musical Instruments. The background information on this page, combined with the information in the interactive, covers the science notes provided in the original BSC book. The overarching science concepts (big ideas) and how they may be scaffolded in sequence are illustrated in the interactive below.

What is sound?

Sound is a form of energy. To create sound, you need an input of energy in the form of movement. Striking, scraping or blowing into an object makes it vibrate. These changes in pressure or waves of vibrations move both the object and the substance surrounding it – usually air. If the vibrations reach our ears, we hear a sound. If there is no movement, no vibrations are created and no sound is made.

Hearing sound

Three things are needed for sound to be heard:

• A source – something that makes the sound – movement is needed.
• A medium – something for the sound to travel through – gas, liquid or solid.
• A receiver – something to detect the sound – for example, our ears.

Sound waves are picked up by our ears. The waves travel via our outer ear to our inner ear, where they are converted to electrical impulses. The electrical ‘messages’ travel along the auditory nerves to our brain, which interprets them as sound.

Volume and pitch

Sound has both volume and pitch. The size (amplitude) of the vibration determines the volume of the sound. The amplitude of the vibration carries the energy. A big vibration causes large sound waves that transmit a lot of energy. The resulting volume of sound is loud. A small vibration causes small sound waves that transmit less energy. The resulting volume of sound is soft or quieter. Sound waves also get smaller the further they travel – unless something acts to boost them. The closer we are to the source of a sound, the louder it is. As we move away from the source, the sound vibrations get smaller – and smaller means quieter, so the volume of sound that reaches our ears diminishes.

The frequency of the vibration determines the pitch of the sound – how high or low it sounds. Frequency is the rate at which a regular event occurs. In the case of sound, this relates to the number of repeating cycles of a sound wave passing a point per second.

Music and sound

The definition of what music is depends on many things including the expectation of the hearer. In general, we interpret random and violent vibrations as ‘noise’ and regular, patterned vibrations as ‘music’.

Music offers a familiar context for exploring the scientific concepts of sound that students can easily relate to. Making and using simple instruments can encourage exploration and scientific questioning.

Prior knowledge

In checking students’ understanding about sound, it is important to learn about the different experiences students bring to the classroom. Music and sound plays an important part in all cultures, including Māori and Pasifika. Talking with whānau and community members will help to broaden the learning and make real-life connections.

Supporting students who have hearing difficulties

It is important to be aware that everyone will hear sounds differently. Hearing loss can be common in children, and it is important to ensure students with hearing difficulties are made to feel included. More support can be found here.

Alternative conceptions

Students may resist the idea that sound requires movement. They may think that they can make an ‘mmm’ sound without moving their facial muscles. But they may be unaware that, to make that sound, they are moving their diaphragm (which may be felt as a tightening in their stomach region) to expel air from their lungs and force it past their vocal chords – making vibrations that can be felt in the throat.

Students may think that sound can only travel through the air and not through solids and liquids.

Students often confuse pitch and volume. They may associate the idea of high pitch with loud volume – a scream for example – and low pitch with soft volume – a low whisper for example.

There are a number of content/vocabulary words that can cause confusion:

• Soft can refer to sound or touch.
• Waves can refer to water waves or sound waves.
• Pitch can refer to a change in frequency or a sports term.