How to calculate acoustic value in a
In addition to providing insulation
and acting as a substrate for roofing, in many situations roof insulations also
need to provide noise reducing characteristics. Building constructions near
airports or other high noise areas require noise reduction principles to be
employed. Today, the noise reduction properties of roof insulation must be
known to properly design structures in high noise areas. Designing
constructions to control noise requires, at a minimum, a basic understanding of
terms and methods used to develop design values for various constructions.
Sound travels through a building component because it sets up vibrations in
that component. Almost all building materials are sufficiently elastic to
transmit sound. Therefore, almost all building materials can be set into motion
by sound waves impinging upon them. Once construction is set into vibration, it
will transmit sound from the source through the construction and the sound will
be heard on the opposite side of the construction. The result is sound
transmission through construction. Sound travels through a building component
because it sets up vibrations in that component. Almost all building materials
are sufficiently elastic to transmit sound. Therefore, almost all building
materials can be set into motion by sound waves impinging upon them. Once
construction is set into vibration, it will transmit sound from the source
through the construction and the sound will be heard on the opposite side of
the construction. The result is sound transmission through construction. The
ability of a construction to transmit sound is dependent upon its mass. The
higher it’s mass, the more it is resistant to vibration caused by sound. If the
mass were extremely small, even faint sound pressure could move it and thus
In addition to mass, numerous other
factors must be considered in proper sound control design. Such factors include
background noise level, and transmission through floors, walls and penetrations
through the construction (which also includes insulation joints). An acoustical
engineer should be consulted when dealing with acoustical design.
Acoustical terms that are important
to know before calculating acoustic values:
When it comes down to it, your ears
are pretty amazing. They allow you to hear sounds as quiet as a whisper and as
loud as a jet engine. How exactly do sound waves get transmitted to your ears
so that you can hear?
It starts with a vibration in the
air. A whisper only vibrates the air a little bit, while a jet engine vibrates
it A LOT. This vibration creates a pressure wave that passes through the air,
spreading out in all directions as it goes. Sound pressure is the pressure
measured within the wave relative to the surrounding air pressure. Loud sounds
produce sound waves with relatively large sound pressures, while quiet sounds
produce sound waves with relatively small sound pressures.
Sound pressure, like other kinds of
pressure, is commonly measured in units of Pascals (Pa). The quietest sound
that most people can hear has a sound pressure of 2 x 10-5 Pa, so this pressure
is called the threshold of human hearing.
- An audio frequency or audible
is a periodic vibration whose frequency is in
the band audible to the average human. The SI unit of audio frequency is the
hertz (Hz). It is the property of sound that most determines pitch. The
generally accepted standard range of audible frequencies for humans is 20 to
20,000 Hz, although the range of frequencies individuals hear is greatly
influenced by environmental factors. In air at atmospheric pressure, these
represent sound waves with wavelengths of 17 meters (56 ft) to 1.7 centimetres
(0.67 in). Frequencies below 20 Hz are generally felt rather than heard,
assuming the amplitude of the vibration is great enough. High frequencies are
the first to be affected by hearing loss due to age or prolonged exposure to
very loud noises.
is the time required for
the sound to “fade away” or decay in a closed space. Sound in a room will repeatedly
bounce off surfaces such as the floor, walls, ceiling, windows or tables. Reverberation
is one of the most significant acoustic properties of a room. Knowing the
reverberation time is essential in characterizing rooms, be they performance
spaces, ordinary rooms or open office spaces.
The laboratory method to measure
acoustical values to use special instruments.
Also, there are some programs
”acoustics calculator” which provide you with a quick overview of the
acoustics in a room. Just type in your room data – measurements and material –
and the acoustics calculator generates a precise overview of reverberation
time, absorption area as well as other relevant information about acoustics.
You can have the report sent to your e-mail or you can print it – either on
paper or as a PDF. First select the shape of the room, and second type in
length, width, and height. The total area of ceiling, floor, walls, doors and
windows is automatically transferred to the further calculation. The total area
for doors and windows will automatically be subtracted from the total wall
area. Then you can get information about the sound level and its distribution
in the building. On the other hand, you can know the exact amount of noise
reduction the building needs so that desired special acoustic panels.
Different collection of acoustic panels for celling, walls, flour, and furniture with changing the materials (foam, fabric, metal, wooden, and plastic), color, and style Acoustima® acoustic panel by Seatup Turkey® products are recommended too.