ACOUSTICS

Acoustics, is the examination of sound behaviors in all aspects. The acoustic quality of a building is generally described in terms of good or bad, referring to the level of easy (or difficulty) speaking is heard. Bad acoustics is characterized by confused hearing and syllables overlap. This can be attributed to large smooth surfaces on the wall, floors or ceilings that reflect the speaker’s voice in a way that they are received by the listeners with the waves sent out previously. In general terms good acoustic is defined as a balance between good sound insulation, reverberation time, background sound and speech intelligibility.

Sound, generated in any indoor areas, reaches the ear or the microphone which converts it to electrical signal to record it by reflecting from the walls that surround the space in different angles as well as traveling straight ahead. So, these endless together at the destination point, adding the acoustic features of the room to themselves.

Noise, due to its characteristic, is any unintended sound that is unwanted or that obstructs other sounds. High sound and vibration levels in work environment will make adverse affects on operations and equipment as well as the safety and health of the workers. Therefore, the acoustic quality of a room is improved by breaking up the smooth surfaces. The positions of these sound absorbers greatly affect the quality of the sound absorption and hearing quality. An effective, cost efficient solution for dealing with this problem is to install a wall-to-wall ceiling cover that improves the hearing by providing high sound absorption.

No matter the size of the room, it is always a good idea to consult with an acoustic consultant. Size and purpose of the space are crucial in the correct acoustical planning. Larger rooms such as lecture halls; movie theaters, concert halls, etc. require shorter reverberation time and good sound reflection to ensure good intelligibility of speech. In concert hall acoustics, reverberation refers to sound that persists in a venue after a tone is suddenly stopped. A hall that is reverberant is called a “live” hall. Aroom that is not reverberant is called a “dead” or “dry” room

Defined as the time it takes for a loud sound to decay to inaudibility after its source is cut off and is usually measured in octave or one-third octave bands. Usually this time is defined as the time, multiplied by a factor of 2, that it takes for the sound in a hall to decay from 5 to 35dB below its steady-state value. The factor of 2 is necessary because reverberation time must conform to the original definition of sound decay which ranges from 0 to -60dB.  Clearly, reverberation time is dependant on the room volume, shape and its ability to absorb sound.

A measure of sound clarity that indicates the easy of understanding speech, it is a complex function of psychoacoustics, signal-to-noise ratio of the sound source, and direct-to-reverberant energy within the listening environment. Speech intelligibility is affected by the reverberation time (shorter is better), shape of the room and background noise (signal-noise-ratio).

The RASTI method is generally used to determine speech intelligibility. This method measures two points between speech and the results are then related to how the intelligibility of the speech is subjectively seen. Different values are obtained according to different values such as shape and size of rooms tested as shown in the following chart: