What is a wave?
• A wave is a repeating disturbance that transfers energy through
matter or space.
• When an object vibrates it causes the particles around it to
move.
• These particles bump into particles close to them, transferring
energy possessed. This continues until they run out of energy.
Longitudinal Waves
Waves transfer
energy without
transferring
matter.
Transverse Waves

Therefore sound can be defined as …
•A form of energy caused by vibrations. This
energy is transferred due to pressure through
longitudinal waves.
In a longitudinal wave the matter in the wave
moves back and forth parallel to the direction of
the wave.
Sound doesn’t travel through vacuum.

Sound can be reflected, refracted, and
absorbed and also shows evidence of
interferencealso be known as echo.
Reflection of sound is and diffraction.
Reverberation of sound is the repeated multiple reflection of sound in any
enclosed space.
Reverberation occurs when the echo produced is as same/strong as the sound
produced by the source.
Refraction of sound
occurs when the wave
travels from one medium
to another.

Wavelength
Wave Speed  f
Time period
Wavelength () is the distance from the center of one compression
to the center of the next compression.
Time period (t) is the time it takes for one full wavelength to pass a certain
point.
Frequency (f) is waves per second.
Wave Speed (s) the distance covered by a complete wave in a given time.

• Compressions
The close together part of the
wave.
• Rarefactions
The spread-out parts of a
wave.
Amplitude is the maximum distance the particles in a
wave vibrate from their mean positions. Amplitude
controls the volume and intensity of sound.
The amplitude of a
longitudinal wave is
determined by the closeness
of the longitudinal waves.
The closer the longitudinal
waves and the farther the
rarefaction lines.
Spring A has greater amplitude than Spring B.

344 m/s in air at 20 C
Speed of Sound depends on:
Type of medium
•travels better through liquids
and solids
•can’t travel through a vacuum
Temperature of medium

Doppler Effect
change in wave frequency caused by a
moving wave source.
moving toward
you - pitch
sounds higher.
moving away
from you - pitch
sounds lower.

Waves interfere in one of two ways: Constructive
Interference and Destructive Interference.

 Frequency of a sound wave is heard as pitch.
 highness or lowness of a sound
High
Low
frequency
frequency
= High pitch
= Low pitch
=
= Long
Free Powerpoint Templates Short
wavelengt

Low pitch. Eg. Fox horn High Pitch. Eg. Pic
Healthy humans can hear from 20 Hz to 20,000 Hz
Ultrasound
- sound waves with frequencies above the normal human range of
hearing.
Ultrasonic sounds have frequencies greater than 20000 Hz.
Infrasound
- sounds with frequencies below the
normal human range of hearing.
Infrasonic sounds have frequencies lower than 20Hz.

Some animals can hear sounds with frequencies greater than
20000 Hz.
a) Dogs (up to 35,000 Hz)
b) Bats (over 100,000 Hz
c) Medical diagnosis.
Medical Imaging
a. Acoustics – the study of sound.
b. SONAR – Sound Navigation and ranging (echolocation).
c. Ultrasound imaging.

Different sounds
that you hear
include
(A) noise
(B) pure tones
(C) musical notes or
beats.
A - can be considered as noise as it has no
pattern.
B – can be considered as a pure tone as energy is
transferred in a single pattern of the wave.
C - musical notes or beats as it has a pattern of

Beats are variations of loudness
(amplitude) and pitch
(frequencies) caused by
interference of two sounds that
slightly differ.
Beats differ depending on the pattern
of amplitude, pitch and caused by
interference of different waves.

Clarinet
It depends on the type of
instrument. There are four
types.
Woodwind. String.
Percussion. Brass.
Flute
Oboe
Piccolo Wo o d wi n d s
ma k e mu s i c
Bassoon
b y b l o wi n g
o n t h e t o p o f

•Some of the simpler instruments are the string instruments. String
instruments make sound with vibrating strings, and the pitch is
modified by the thickness, tension, and length of the string.
Cello Guitar Harp
Violin
Electric
Guitar

Drum
• Percussion instruments make music by
striking, shaking or scraping them. Piano
Tambourine
Cymbals Xylophone Maracas

Brass instruments make music
by buzzing lips while blowing.
Trombone
Trumpet
Tuba
French Horn