Muffling sounds
Soft materials soak up sound.
Making sounds quieter
To muffle a sound means to make it quieter. Wrap a ringing alarm clock in a thick towel and it sounds much softer. Soft, thick materials absorb sound.
Soft materials have lots of tiny air spaces. Sound bounces around inside them and loses energy, so less sound gets through.
Sound insulators
A material that stops sound passing through is a sound insulator. Foam, cloth, carpet and cork are good sound insulators. Recording studios have foam walls so there are no echoes.
Egg boxes, carpets and padded walls are used in music practice rooms and radio studios to stop echoes.
Testing materials
You can test which material muffles sound best. Wrap a sound source in different materials. Measure how far away you can still hear it, or use a sound meter.
Using the same sound source at the same volume, and the same thickness of each material, makes the test fair.
Muffling in everyday life
Curtains and rugs make rooms quieter. Car makers put soft materials inside doors to block road noise.
An empty room sounds echoey. When furniture, rugs and curtains are added, it sounds much quieter and softer.
What I learnt
- I know that soft, thick materials muffle sound.
- I can plan a fair test to compare materials.