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
• These particles bump into particles close to them, transferring
energy possessed. This continues until they run out of energy.
Therefore sound can be defined as …
•A form of energy caused by vibrations. This
energy is transferred due to pressure through
In a longitudinal wave the matter in the wave
moves back and forth parallel to the direction of
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
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
Wave Speed f
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
Frequency (f) is waves per second.
Wave Speed (s) the distance covered by a complete wave in a given time.
The close together part of the
The spread-out parts of a
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
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
•can’t travel through a vacuum
Temperature of medium
change in wave frequency caused by a
moving wave source.
you - pitch
from you - pitch
Frequency of a sound wave is heard as pitch.
highness or lowness of a sound
= High pitch
= Low pitch
Free Powerpoint Templates Short
Low pitch. Eg. Fox horn High Pitch. Eg. Pic
Healthy humans can hear from 20 Hz to 20,000 Hz
- sound waves with frequencies above the normal human range of
Ultrasonic sounds have frequencies greater than 20000 Hz.
- 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
a) Dogs (up to 35,000 Hz)
b) Bats (over 100,000 Hz
c) Medical diagnosis.
a. Acoustics – the study of sound.
b. SONAR – Sound Navigation and ranging (echolocation).
c. Ultrasound imaging.
that you hear
(B) pure tones
(C) musical notes or
A - can be considered as noise as it has no
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
Beats differ depending on the pattern
of amplitude, pitch and caused by
interference of different waves.
It depends on the type of
instrument. There are four
Piccolo Wo o d wi n d s
ma k e mu s i c
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
• Percussion instruments make music by
striking, shaking or scraping them. Piano
Cymbals Xylophone Maracas