Waves 2 - Section 1: Sound

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SOUND WAVES - compressional waves formed
from vibrating objects colliding with air molecules

▹ Remember compressional waves are made of compressions

and rarefactions.

5

Speed of Sound -
depends on temperature
and state of medium

▹ Sound travels in solids and

liquids - molecules are closer
together than gas molecules

▹As a medium temp rises,
molecules move faster
conducting sound waves faster.

HUMAN
HEARING

STAGE 2

The middle of the
ear has three bones
called the hammer,

anvil and stirrup

which amplify sound

waves

STAGE 1
Ear gathers

compressional
waves which

vibrate a tough
membrane called

the eardrum

STAGE 3
The inner ear

contains the cochlea

which vibrates

sending auditory
nerve impulses to

the brain

STAGE 4

The brain decodes
and interprets nerve

impulses

INTENSITY

The amount of energy that
flows through a certain
area in a given amount of
time.

LOUDNESS

The human perception of

sound intensity which is

measured in decibels

PITCH - how high or low a sound seems to be, which is

related to frequency of a sound wave

SUBSONIC

< 20 Hz

HUMANS CAN HEAR

20 - 20,000 Hz

ULTRASONIC

> 20,000 Hz

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