Soundproofing by Apocalypse Acoustics

SOUNDPROOFING By Apocalypse Acoustic Sciences Corp

Soundproofing is any means of reducing the sound pressure with respect to a specified sound source and receptor. 
There are several basic approaches to reducing sound: increasing the distance between source and receiver, using noise barriers to reflect or absorb the energy of the sound waves, using damping structures such as sound baffles, or using active anti noise sound generators.

TWO PROBLEMS To Be Addressed:

• Two distinct soundproofing problems may need to be considered when designing acoustic treatments - to improve the sound within a room (See anechoic chamber), and reduce sound leakage to/from adjacent rooms or outdoors. 
• Acoustic quieting, noise mitigation, and noise control can be used to limit unwanted noise. 
• Soundproofing can suppress unwanted indirect sound waves such as reflection that cause echoes and resonances and that cause reverberation. 
• Soundproofing can reduce the transmission of unwanted direct sound waves from the source to an involuntary listener through the use of distance and intervening objects in the sound path.

For More Information, Solutions and Techniques in Soundproofing, please do visit us at www.apocalypseindia.com or Call +919395333255

Apocalypse Acoustic Sciences Corp provides complete acoustic design, noise & vibration control for facilities of all types whether it is to support unaided speech or live music or to effectively optimize the acoustical design for speech intelligibility & Musical Acoustics.

NOISE CONTROL By ACOUSTICS ASIA

INTRODUCTION TO NOISE CONTROL By ACOUSTICS ASIA
Definitions and Background 
What is Noise? 

• Noise is disagreeable or unwanted sound.  In many instances, noise is a relative definition of a sound since one person’s music may be another person’s noise.  It is difficult to give a very clear definition of an irritating noise.  Generally, noise is an unwanted sound, regardless of its intensity or duration. 
   
• Noise Pollution has been recognized as a major threat to human well being.  Much discussion and legislation has evolved in an attempt to recognize and combat the problem of noise pollution.  It has been recognized that noise, of sufficient intensity, can damage hearing and be classified as a hazard.  
• In combating the problem of noise pollution it is necessary to use a means of measuring noise levels and a system of classification.  The decibel is a number which relates sound intensity or sound pressure.  When most people use the term decibel or discuss noise levels in decibels they are referring to decibels as related to the “A-weighted” scale or, dBA. 
• The A-weighted scale parallels the sensitivity of the human ear and uses the lowest audible sound that the human ear can detect as the reference point for determining the decibel level of a noise.   
  The reference intensities used above represent the threshold of audibility where sound is just loud enough to be heard.  At 140 decibels or more acute pain is experienced.  Some common noise values are as follows:  

• Ordinary conversation – 60 dBA.
• Heavy traffic – 80 dBA.
• Cocktail Party – 90 dBA.
• Moving subway train – 100 dBA.
• Riveting gun – 130 dBA.
• Hard rock band – 100 to 138 dBA.
• Jet plane heard at close range – 150 dBA 

• Any noise rating above 80 dBA produces physiological effects and any long term exposures at much or above 90 or 100 decibels will cause permanent damage to a person’s hearing.  An increase of 10 dBA is a doubling of loudness with respect to the human ear. 

• Noise generally consists of many tones with varying rates of vibration or frequency.  The frequency expressed in cycles per sound or hertz (HZ) usually is in the range of 20 to 20,000 cycles per second. 
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• The ear is not very responsive to very low or very high tones as it is to the tones of medium frequency. 
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• The dBA scale matches the response of the ear, and is therefore well suited for evaluating noise as it relates to human beings. 

For Noise Control Solutions & Perfections:
Apocalypse Acoustics Sciences Corp
#605, 6th Floor, Vani Nilayam, Sebastian Road, Secunderabad-3. Telangana. India.
Ph: +91-40-64561266. Fax: +91-40-27531331. www.apocalypseglobal.org

Reverberation Time@acousticsasia

REVERBERATION TIME

Reverberation is linked to the speed at which sound energy disappears in a room. 

An unfurnished room or space with hard surfaces, such as a church or House of Worship, is perceived as being more reverberant than a well-furnished living room. 

• The reverberation time is usually defined as the time it takes for sound to decrease by 60 dB. 

• To determine the length of this time, different parts of the reverberation curve are used. 

• When measuring Early Decay Time (EDT), an interval of 10 dB is used. 

• At T20, an interval of 20 dB is used. When determining T20, the evaluation does not start until after the sound level has already fallen by 5 dB. 

• At T30, an interval of 30 dB is used and here, too, the evaluation starts after the sound level has fallen by 5 dB. If the reverberation curve is straight, the EDT, T20 , T30, will all produce the same value. 

• In practice, the reverberation curve is not straight (dashed line), which means that the descriptors will differ. The descriptors T20 and T30 are usually called “late reverberation times” as they measure at the later part of the curve.

EDT is called “early reverberation” and is considered to better reflect how we perceive the reverberance in the room.

For more technicalities and answers please mail us at apocalypse@mail.org or call us at +919395333255. Noel Flemming. Copyright 2015. Apocalypse Acoustics.