Simple presentation about sound. Simple to understand.

1. Sound Proofing
Making things Sound Proof

2. Contents
• Part 1 Terms Used In the Study of Sound
• Part 2 Behaviors and Measure of Sound
• Part 3 History of Sound
• Part 4 Uses of Sound
• Part 5 Sound Proofing
• Part 6 Effects of Sound
• Part 7 Quiz

3. Part 1 Terms Used In the Study of Sound
• Rarefaction is a region in a sound wave in which the density of
the sound medium is less than normal.
• Resonance frequency is the frequency at which an object
would vibrate naturally if disturbed.
• Sound medium is a substance in which sound waves travel. Air,
for example, is a sound medium.
• Sound quality also called timbre, is a characteristic of musical
sounds. Sound quality distinguishes between notes of the same
frequency and intensity that are produced by different musical
instruments.
• Ultrasound is sound with frequencies above the range of human
hearing—that is, above 20,000 hertz.
• Wavelength is the distance between any point on a wave and the
corresponding point on the next wave.

4. Part 1 Terms Used In the Study of Sound
• Condensation is a region in a sound wave in which the sound
medium is denser than normal.
• Decibel (dB) is the unit used to measure the intensity of a sound.
A 3,000-hertz tone of 0 dB is the softest sound that a normal human
ear can hear.
• Frequency of a sound is the number of sound waves that pass a
given point each second.
• Hertz is the unit used to measure frequency of sound waves.
One hertz equals one cycle (vibration, or sound wave) per second.
• Intensity of a sound is a measure of the power of its waves.
• Loudness refers to how strong a sound seems when we hear.
• Noise is a sound that is unpleasant, annoying, and distracting.
• Pitch is the degree of highness or lowness of a sound as we hear.

5. Part 2 Behaviors and Measure of Sound
• Sound originates in the vibration of an object. The vibrations make
the area around it vibrate also, producing waves which our body
translates then as sound.
• The area in which the sound waves travel is called the sound
medium.
• As there is no medium in space, there is no sound in space.
• Scientists measure sound in frequency and pitch, wavelength,
intensity and loudness and quality.
• This experiment focuses on the intensity of a sound. The intensity of
a sound is a measure of the power of its sound waves. This is
measured in decibels. Decibels use a logarithmic scale. For
example, 50 dB represents 10 times as much power as 40 dB.
• Intensity is different than loudness because the pitch of a sound
determines how loud it is, unlike intensity , which measures the
power of a sound

6. Part 3 History of Sound
• One of the earliest researchers of sound was Pythagoras, a Greek
philosopher and mathematician, who experimented on the vibration
of strings in the 500‘s B.C.
• Around 400 B.C., a Grecian named Archytas observed faster motion
results in high pitched sounds.
• The Greek philosopher Aristotle suggested that the movement of air
carries sound to our ears.
• In 1600’s when Galileo showed that frequency of sound waves
determines the pitch.
• Thomas Edison, in 1877, invented a phonograph which could replay
a sound.
• Stereophonic phonographs and discs appeared in 1958 and audio
compact discs were introduced in Japan and Europe in 1982.
• A recent discovery in acoustics occurred in 2000 when active noise
cancellation (ANC) and active structural-acoustic control (ASAC)
were actively used to suppress unwanted noise.

7. Part 4 Uses of Sound
• Ultrasound is sound with frequencies above the range of human
hearing. Technicians use ultrasound to clean delicate instruments,
manufacturers use it to deflect flaws in metals and other materials
and physicians use ultrasound to diagnose brain tumours,
gallstones and other disorders.
• Sonar works when sound waves travel until they reach an object.
The sound waves then travel back to their original location. By the
speed of the sound waves returning, scientists and geologists can
tell how far an area is away from them, such as fishing boats
detecting schools of fish.

8. Part 5 Sound Proofing
There are two ways of silencing the sound
• Through passive absorption
• Through sound barriers
Passive Absorption is when sound passes through an absorptive
Material, such as fibreglass. Sound is forced to change directions
whenever encountering another fibre. Absorbent material work best
when there is a reflective material behind them.
Sound Barriers uses their mass to stop the energy of the sound
waves.
Note: We will be using Passive Absorption techniques in our project
for sound proofing the box.

9. Part 6 Effects of Sound
• Too much exposure to loud noises can cause temporary or
permanent hearing loss.
• Constant noise, even not extremely loud, can cause fatigue,
headaches, irritability and tension.
• If being exposed to an area surrounded with noise from 75 - 84
decibels minor hearing loss may develop, while at 125 decibels a
person will feel pain and discomfort, which at 160 decibels a person
will have a ruptured ear drum.
• Noise levels must be posted if they are over 80 decibels.
• It is suggested that workers who are exposed to daily average noise
levels of 85 decibels and over should wear muffs, ear caps or pre-
moulded plugs.
• The best noise reduction is through soundproofing the building or
work area.