Tyler Woodruff

Corbett

4th

Sound and Soundproofing

Sound is a very crucial part of living on earth. It is seen everyday and the science behind

it mostly goes unnoticed. The science of sound is extremely interesting yet it is oddly basic.

Sound can also be described as peaceful and destructive however it is believed that it is to be left

to the one listening to the sound to answer that question.

Sound is a very interesting part of physics and the real world today and

throughout history. Sound can be defined in many different ways depending on how it is

perceived. “The sensation produced by stimulation of the organs of hearing by vibrations

transmitted through the air or other medium.” Dictionary.com is one way sound is defined.

However, if looked at from a physics point of view, sound can be defined as, “mechanical

vibrations transmitted through an elastic medium, traveling in air at a speed of approximately

1087 feet (331meters) per second at sea level.” Dictionary.com. Sound can only be present if

there are mediums for it to travel through. Some of the different types of sources that it can

use to vibrate through are forms of matter, gasses, liquids, and solids. If there is no medium

for sound to travel through then sound can not exist in that situation that is also know as a

vacuum. Space is the best example of a vacuum. Sound travels in the form of oscillating waves.

Longitudinal waves are waves that travel through solids, liquids, and gasses, and are sometimes

called compression waves. These forms of waves are special because they are transmitted as

alternating pressure deviations that differ from the equilibrium pressure. The way that sound

is acutely emitted is when the matter that is used as a medium for the deviation in the pressure

oscillates back and forth it causes the energy in the waves to switch from potential to kinetic

rapidly thus causing sound.

There are many measurement of sound that all show a different property about each

individual sound. Frequency is the first type of measurement of sound. According to

Audimute, “Frequency is the number of occurrences of a repeating event per unit time.”

Audimute.com. The standard unit for measurement for frequency is hertz, which is named after

the German scientist Heinrich Hertz. Frequency is measured by putting the number of times a

sound oscillates over the period of time measured. Amplitude is the next way that sound is

measured. This is basically what is called volume in laymen terms. “Amplitude is

the magnitude of change in the oscillating variable with each oscillation within an oscillating

system.” Audimute.com. Amplitude is used to measure the total output through pressure and

noise from an oscillating source. RMS is the unit of measurement for amplitude. Frequency and

amplitude are the two most commonly used terms to describe sound and its specifications. There

are also a few other units of measurement that can be used to determine different sound’s

individual qualities. Watts are one of these units of measurement. In the study of sound and how

sound works, “Watts can be used to describe how much total output that the system that is

making the sound can put out.” Kamisiński, T, J Rubacha, and A Pilch. This is used in many

everyday things like car stereos and home entertainment systems. The amounts of watts show the

total potential output that the entire sound system can produce. All of these measurement help

show how sound works and how sound is measured, and the measurements can help study the

properties of sound.

The anatomical definition of sound is one that most humans describe first before they

understand the physical meaning of sound. These two interpretations have sparked many debates

on what the true meaning of sound should be. This also sparked the old trick question “If a tree

falls in the forest and no one is around to hear it, then does it make a sound.” Unknown. The

anatomical definition of sound basically states that sound is a stimulus caused by a change in

air pressure that causes oscillations to be perceived as a natural sense of the body. When sound

enters in through the ear to be perceived as a sense it vibrates little hair follicles in your ear

which in turn cause you to perceive the stimulus as a sound. However, these little hairs never

grow back once they are destroyed, and they are very easy to destroy. This is all why sound

proofing is a huge part of the world today.

Sound can be a very beautiful and productive thing in our world today, and it has

been for a very long time now. However, it can also be a huge disturbance to those around that

do not care for the certain sound being emitted. This is where soundproofing and sound

absorption come into play. “Sound proofing is the act of completely sealing of a room or

enclosure so that no sound can escape.” Doutres, Olivier, and Noureddine Atalla. Soundproofing

can be a very difficult and very expensive thing to do depending on what is being soundproofed

and how big the area that is enclosing the object that is making the sound takes up. Sound is a

very tricky element of physics to deal with mainly because sound uses mediums to travel

through; therefore sound can not just be boxed in and never heard again. According to Thomas

Kletschkowski, “Soundproofing [normally] requires special materials and special equipment

because the noise level that the sound will come out at when in an enclosed room all depends on

the materials used, the structure of the room, and flexibility of the walls.” Thomas

Kletschkowski. In the structure of a normal room there is almost no means used for

soundproofing, mostly because there is no reason for complete sound blocking in a normal room.

Most rooms consist of a layer of 5/8 inch thick drywall screwed to a row of two by four inch

pieces of wood, with a layer of insulation, and then another piece of 5/8 inch thick drywall on the

other side. This set up has a STC rating of 38-41 dB. “The STC rating or Sound Transmission

Coefficient, measures the amount of sound that escapes a room as perceived in

decibels.”soundproofwindows.com. At this STC rating loud talking in the other room can be

heard yet it is not clearly audible. This may work for many households that do not have that

much loud talking going on and do not need to have their walls soundproofed. However, for

people that do need their walls soundproofed there are many options to choose. Most of these

options for sound blocking use the same concept to block sound from escaping or entering.

Sound travels in wavelengths and the frequency of the wave lengths vary depending on the pitch

of the noise that is being emitted. Sounds with higher pitches have higher frequencies, thus have

shorter wavelengths. On the other hand noises with lower pitches have lower frequencies and

have smaller wavelengths. Since earth has an atmosphere with air in it sound is free to travel

almost anywhere, and when a sound wave runs into a wall or another solid object it has the

ability to go through that object depending on its wavelength and the size of the object. The way

this works is that the sound wave enters the object and if the length of the wave is longer than the

object it enters then it will pass through to the other side of that object, and if it is shorter then

the object then it will not pass through that object. This is why bass and other lower pitches are

what is most often heard through walls when the sound is being emitted from the other side of

the wall. Soundproofing materials help with this affect in the way that they make the walls

thicker and denser so that less sound can pass through the wall. Other types of sound blocking

materials are made of very dense rubber and they actual repeal the sound back at its source.

Along with sound blocking materials there are also sound absorbing materials. Sound absorption

is a totally different task compared to sound blocking. While sound blocking deals with

completely eliminating all sound that is produced by an object, sound absorption is used to just

dim the sound a little bit and to make the quality of the sound actually heighten. Sound

absorption works by using many different items to “catch” the sound and take most of the reverb

and echo out of it; thus giving it a cleaner and more controlled sound. Some of the materials that

are used to achieve this affect include sound absorption panels and sheets, and also sound

foam. “[The] sound absorption panels are wood framed structures that have a cloth covering and

is spaced out with a small amount of insulation on the inside of it.” Audimute.com. These panels

work by letting sound pass through the cloth while still reverberating off of it. Then after the

sound passes through the cloth it then gets dampened by the cloth which in turn cuts back on the

noise without completely blocking it out. These work great for recording studios that need good

sound back for acoustics and recordings. The foam and the sound absorption sheets work with

almost the same principal as the sound absorption panels. They work by letting the sound get

caught inside their many ridges and letting the waves bounce around in many random ways

while also letting it be dampened inside the air filled structures. These sound sheets and sound

foam blocks also block more sound then the panels will because they have more area for the

sound to be absorbed in. These work the best for things like drum room which need sound

absorption materials but still need to sound good. In conclusion, sound has many aspects to it

and it is a very hefty task to block it and keep it under control.

In conclusion sound is a magnificent part of the world as it is known in this day and age

and it will not be leaving anytime soon. The concept of sound and how it works is one of the

most interesting and complex ideas in the scientific world today. However, sound still has its

downfall and its always needing to be blocked in some place at some time. Although is has its

downturns sound is still one of the most fascinating beautiful objects of physics on earth to date.