Sound and Hearing

Frequency (hertz - Hz)

The number of complete waves passing a point each second.

Source of the sound is vibrating at the same number of CYCLES PER SECOND and the frequency of the waves it makes.

High frequency = high pitch

Low frequency = low pitch

Oscilloscope

Sound waves can be shown as a trace on an oscilloscope

Wavelength

The distance between any two identical points on neighbouring waves

Amplitude

Half the heigh of the wave is called an amplitude

The loudness or intensity of a sound depends on the amplitude of the wave

Louder notes = More energy = Bigger Amplitudes

Hearing

Sound travels through the air and into the ear causing the eardrum to VIBRATE

Vibrations pass from the eardrum to the COCHLEA in the INNER EAR where they change to ELECTICAL IMPULSES (signals)
A NERVE takes this message to the brain which converts this IMPULSE into sound.

Loud sound can damage the eardrum or cochlea.

To avoid this people wear ear protection
Unpleasant sound is called NOISE.

Wax, ear infections and getting older can  affect hearing.

Sound can be measured using a
SOUND INTENSITY METER
It measures loudness in DECIBELS (dB)

THRESHOLD OF HEARING is the quietest sound and is 0dB

Soft materials ABSORB sound

Soft materials are used in SOUNDPROOFING

The GAP between double glazing contains few particles and so is also used for soundproofing.

Sound and Light

Light energy can travel through space (a vacuum) but not sound energy

Light travels nearly a million times faster than sound.

Light travels 300 million meters a second in air
Sound travels about 300 meters per second

Sound

A form of ENERGY made when things VIBRATE

Vibrations

Passed on by PARTICLES
Needs a substance to pass through
Can travel through SOLIDS, GASES or LIQUIDS BUT not a Vacuum

Speed of sound is faster if particles are closer together.

When sound moves from one place to another is has been TRANSFERRED.

Sound ENERGY travels in all directions unless something stops them.