Ready for action?
Resources
Downloadable Resources
Decibel Meter app on a smartphone (Apple, Google Play)
Oscilloscope app on a smartphone (Apple, Google Play)
Tangible Resources
Decibel meters (optional), coloured markers, A4 sheets, A2 sheets to make posters.
Preparation
Download apps onto smartphones or tablets.
Goals, messages & concepts
Specific goals
- Become familiar with the decibel – the unit of sound intensity – and its relationship to loudness.
- Recognise how to use decibels as a unit of measure.
- Measure sound intensity level in decibels and determine the hearing threshold and the pain threshold, and other sounds on the decibel scale.
Specific messages
- Sound intensity is measured in decibels.
- The volume of a sound can be harmful to your health.
Main terms
- decibel
- loudness
- sound intensity
- hearing threshold
- pain threshold
Practices & skills
STEM practices
- Analysing and interpreting data
- Engaging in argument from evidence
- Obtaining, evaluating, and communicating information
- Planning and carrying out investigations
Soft skills
-Management skills
-Course of activity
step 1
Students will begin by listening to a fragment of a 2.5 minutes film Chicken Song on YouTube (see resources). Use the film to introduce the questions, “What is silence?” and “What is the difference between silence and noise?”
step 2
Using an online sound generator, students should note that there are sounds on the border of audibility and sounds at which we feel pain. They will examine the level of audible sounds for older and younger family members to explore their hearing threshold. Using the Oscilloscope app, students should watch sounds of varying frequency and volume on an oscilloscope.
step 3
After the discussion, students will work in pairs on A4 paper to present their own ideas to graphically express their request for silence. The teacher can use the posters to ask for silence in the classroom.
step 4
Next, present a list of different sounds on the board. Examples are:
- Drill
- Leaf in the wind
- Dishwasher
- Running water
- The hum of a fan on a computer
- Conversation
- Whisper
- Buzzing fly
- Rock concert
- Jet engine
- Passenger plane
Students will rank these sounds in order of loudness from quietest to loudest. They will then consider how to measure loudness.
step 5
Introduce the concept of sound intensity to describe loudness, and explain what a decibel is. Students will perform calculations to identify the correlation between intensity and decibels (when sound intensity doubles this results in an increase of only 3 decibels).
step 6
Students will measure sound intensity in the room in decibels – firstly, when everyone in the class is quiet and secondly, when everyone shouts. They will then watch this video to learn about the 10 loudest sounds and their intensity level in decibels.
step 7
Finally, on A3 sheets, students will work in groups to create posters depicting the sources of different sounds (drawings) against a decibel scale ranging from 0 dB to 130 dB.