What is Reverberation by Apocalypse Acoustics Part One

What is Reverberation???

Reverberation is another name for what most people know and understand as echo. 

The following analogy explains what reverberation is quite concisely without getting overly technical.

If you press the accelerator pedal of a car, the car accelerates to a certain speed. If the road is smooth and level the speed will remain constant. With a constant force on the accelerator, the engine produces enough horse power to overcome frictional and aerodynamic losses and maintain a steady and even speed, or steady state condition. If you take your foot of the off the accelerator, the car will gradually slow, and come to a stop.

Sound within a room acts similarly to this. When a loudspeaker is turned, it emits noise into the room that quickly grows to a certain level. This level is the steady state or equilibrium point at which the sound energy radiated from the loudspeaker is enough to over come loses in the air and at the room boundaries. A greater sound energy radiated from the loudspeaker will result in a higher equilibrium level, whereas less energy to the loudspeaker will result in a lower equilibrium level. If you push your foot flat to the floor in the car the equilibrium or speed will be much faster, than those Sunday drivers who only slightly depress the accelerator pedal.

When the loudspeaker is turned off, it takes a finite length of time for the sound level in the room to decay to inaudibility. This means there is an exact amount of time from when the loudspeaker is turned off until the sound from the speaker cannot be heard.

For most environments such as conference rooms, classrooms, sports halls, offices and the typical working environment or public space, the longer the time between the noise source stopping and the noise becoming inaudible, the worse the acoustic environment is perceived. This is because a lot of words and noises overlap one an another.

You can say, 

” What on earth is reverberation time? 

How do I treat it.?

” In a room with high absorption or with few reflections the sound dies immediately or very quickly allowing Us to reply with the right answers.

Please Refer Part Two of this Resource, What is Reverberation?

For Any Clarifications call us at +919395333255 or Email us at apocalypse@mail.org

Visit us at www.apocalypseindia.com

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. 
•  
• 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. 

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.

Acoustics: Analytical Thinking by Apocalypse

Acoustics...How Important?

A church’s physical size and structure, as well as sound requirements for the service, cover a broad and varied range.

The majority of churches require some acoustical treatment. 

And it is best to hire a trusted outside firm to handle the job (visit other churches where that firm has cured acoustical ills).

That said, before hiring an independent professional to do a thorough acoustical analysis of your church, it is a good idea to get a ballpark estimate of what it will take to fix the problems.

By the way, dispel yourself of the myth that acoustical challenges — especially severe ones — can be cured by console equalization, or even “room EQ.”  Here’s the information you need to provide an off-site analysis of your space/room acoustics: 

Room Dimensions

 This information allows the calculation of total room cubic volume, which is necessary to determine the existing sound absorption and derive the change needed to reach a desired acoustical result. Include length, width, height plus sides and ceiling peak.

 Surfaces

 What is the existing composition of the floor, walls and ceiling? Marble, carpet, wood, drywall, masonry, acoustical tile, drywall and plaster will all contribute their unique sound properties to the acoustical environment. The addition of acoustical material does not produce a change in total sound absorption by its full rating unless the surface being covered is extremely reflective. If the existing wall has some absorptive value, a new layer of acoustical material may provide only a marginal difference in absorption. 

 Seating

 Is seating hard or soft? Padded pews will prevent a big difference in sound when attendance may be down — during summer vacation, for example. If all surfaces are hard (marble floors, wood ceilings, plaster walls and wooden pews) acoustics will vary more with attendance and season. Heavy winter coats will reduce echo whereas summer attire and fewer folks will provide less absorption, allowing more reverberation.

 Capacity

 As implied above, there may be a need to compromise acoustics between perfect attendance and vacation time. How many people (maximum, minimum, typical) attend and how often? Do you want it to sound good most of the time? 

And Many other things Like Photos, Types of Service, Reverberation Time will give good information for independently asses and analyze a solution for the space/room.

For clarifications or technical, please do call us at +919395333255 or mail us at apocalypse@mail.org.

flawless perfections @apocalypse acoustic sciences corp.