INTRODUCTION TO NOISE CONTROL By APOCALYPSE ACOUSTICS SCIENCES CORP
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. The ear is not very responsive to very low or very high tones as it is to the tones of medium frequency.
The dBA scale matches the response of the ear, and is therefore well suited for evaluating noise as it relates to human beings.
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Reverberation is linked to the speed at which sound energy disappears in a room.
An unfurnished room with hard surfaces, such as a church, 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.
To understand more about Reverberation, mail us at email@example.com or call us at+919395333255. Noel Flemming. Copyright 2015. Apocalypse Acoustics Sciences Corp.
Noise is considered a serious threat to the environmental health. Some of the adverse effects of noise pollution are given below:
- It interferes with speech. In the presence of noise we may not able to follow, what the other person is saying.
- Noise leads to emotional and behavioral stress. A person may feel disturbed in the presence of loud noise such as produced by heating of drums.
- Noise may permanently damage hearing. A sudden loud noise can cause severe damage to the eardrum.
- Noise increases the chances of occurrence of diseases such as headache, blood pressure, heart failure, etc.
- Noise leads to increased heart beat, constriction of blood vessels and dilation of pupil.
- Noise is a problem especially for patients who need rest.
- Noise may cause damage to liver, brain and heart.
Noise pollution describes any sound created by people, animals, and machines that disturbs the environment. With these noise pollution facts, you can better understand its causes, health risks, and protection techniques.
We master noise, we do provide end to end solutions, in residential noise, industrial noise, outdoor noise, vehicular noise pollutions, sound pollution, unwanted sound, noise isolation’s, Vibration control, & white noise control solutions.
For Noise Control Solutions and Perfections please mail us at firstname.lastname@example.org or visit us at www,acousticsglobal.com
In churches, synagogues and worship centers large or small, words and music can sound incomprehensible to the congregation if sound is not properly controlled.
- Poor sound quality is common in churches because of an abundance of hard surface materials. Brick, marble, stone, tile, glass, wood and sheet rock are all acoustically reflective.
- Sound waves bounce back and forth between parallel surfaces, creating a confusion of noise until they finally decay. Even the most strategically-placed speakers and microphones will not compensate for poor acoustics.
Every room needs some absorptive materials and some reflective materials to get the right acoustic mix for the room’s intended purpose. The challenge is to find that balance.
- Apocalypse Acoustics Wall Panels and Acoustic Panels from Acube acoustic inc. are designed to absorb airborne sound energy and reduce a room’s overall noise, reverberation and standing waves—creating interiors that reduce the din without sacrificing the divine.
Perfections @Apocalypse Acoustics visit us at http://www.acousticsglobal.com
Most #sound #reinforcement #systems are located indoors, and the acoustical properties of the enclosed space have a profound effect on the system’s requirements and its performance.
Our study begins with a #discussion of #sound #absorption and #reflection, the growth and decay of #sound fields in a room, #reverberation, direct and reverberant sound fields, critical distance, and room constant.
If analyzed in detail, any enclosed space is quite complex acoustically.
For further Simplifications & Perfections in acoustics, we are avaliable@Apocalypse Acoustics.