Sound is a vibration that typically propagates as an audible wave of pressure, through a transmission medium such as a gas, liquid or solid. Humans can hear sound waves with frequencies between in the range of about 20 Hz to 20 kHz. Intensity of sound is measured in decibels (dB). On the decibel scale, the least audible sound (near total silence) is 0 dB. A sound 10 times more powerful is 10 dB. A sound 100 times more powerful than near total silence is 20 dB. A sound 1,000 times more powerful than near total silence is 30 dB. Here are some typical sounds and their decibel ratings:
Figure 1: Decibel scale
In order to eliminate sound and create “silence” we have the following options:
- Remove the sound source
- Prevent the sound from reaching our hearing
Since it is practically impossible to completely remove the source of sounds in today’s urban environment, it is more realistic to try and reduce the transmission of sound from the source to an involuntary listener. Sound transmission can be reduced using the following measures:
- Distance: increasing the distance between the sound source and the listener results in a progressively lower sound intensity for the listener.
- Sound insulation: decreases or eliminates the effects of exterior noise by placing objects in the sound path. There are two types of transmitted sound in a building: airborne and impact. The main focus of airborne residential sound insulation in existing structures is the windows and doors. Just think about sleepless nights in hotel rooms with poor sound insulation, hearing noises from the hall all night long – and the value of doors with good sound insulation becomes obvious.
- Sound absorption: converts part of the sound energy into a very small amount of heat in the absorbing material, rather than sound being transmitted or reflected. The best sound absorbers require the correct material composition and form. A typical example is the “pyramids” in recording studios or sound absorbing panels in libraries.
The world’s quietest room is an “anechoic chamber” created in 2015 by Microsoft at their headquarters in Redmond, Washington, USA. It is used for formal product testing, for research into the sound different things make – the sound of a cell phone and its various functions, the sound of a surface tablet at rest, improving Skype call performance. The officially measured sound intensity there was registered as -20.3 dB.
Figure 2: Microsoft’s anechoic chamber
An anechoic chamber is so quiet it becomes unbearable after just a short time. You can actually hear your heart beating; sometimes you can hear your lungs or your stomach. In an anechoic chamber you become the sound. Maybe this could be called “the sound of silence.”
There are several solutions that can help you remove the sound source or prevent the sound from reaching our hearing - check KNAUF INSULATION sound insulation solutions and find out more:
KNAUF INSULATION BOARD
Mineral wool products provide some of the best qualities and performance related to sound insulation, sound absorption and the sound reduction index on the market. Similarly, these characteristics are certainly as important as considerations like thermal conductivity or fire resistance. Mineral wool boards can be used as a core element in doors, road sound barriers, machine production and sandwich panel production, assuring excellent sound absorption and sound insulation (up to 32 dB) designed to prevent or reduce noise produced by traffic or industry.
KNAUF INSULATION SOUND SUPREME BOARD
This high-performance insulation core is a new product on the market and boasts excellent sound reduction index numbers. It can be used in various applications where high sound insulation performance is required – in doors, walls and floors (up to 43 dB), providing maximum comfort, good working conditions and an overall pleasant environment.
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- 2. www.byus.com/physics/decibel, (2017)
- 3. T. Tornhill: The worlds quietest place, www.dailymail.co.uk/sciencetech, (2012)
- 4. J. D'Onfro: Step inside the quietest room in the world, www.businessinsider.com, (2015)
- 5. R. Swatman: Microsoft lab sets new record for the world’s quietest place, www.guinessworldrecords.com, (2015)