Factors affecting acoustics of building and their remedies

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Acoustics deals with the generation, propagation, reception and analysis of sound which is branch of physics. Study of sound waves plays an important role in the fields of engineering and non engineering applications. Factors that acoustics of a building are reverberation time, loudness, focussing, Echelon effect, resonance, noise and Echo.

When the reverberation time is too large in a hall then there will be an overlapping of successive sounds resulting in loss of clarity and echo. If the reverberation is very less, then the loudness will be insufficient. Hall is considered as dead by speaker. Hence, it is very important that the reverberation time in hall should not be very short or large. A satisfactory value of the reverberation time is called as optimum reverberation time. These reverberation times can be controlled by providing many windows and ventilators, partially covering the walls, ceiling, back of the chair with sound absorbing materials like fibre board, felt, glass, wool etc. Curtains with folds can be used to cover windows, floor with carpets; walls are decorated by pictures and maps.

Degree of sensation of NRG Acoustics SG-4 produced on the ears is the loudness. Level of audibility goes below if the intensity of sound is weak. For satisfactory hearing, sufficient loudness in the hall is important. Loudness of sound can be increased by large polished wooden reflecting surfaces above the speakers, using good quality loudspeakers are very essential, low ceilings helps in better reflection of the sound.

Sound waves falling on the concave surface of the building after reflection get focused to a point. Intensity of sound is maximum at those points and zero at the other points and this is called as the focusing effect. Equal distribution of sound in the hall is achieved if there is no curved surface in the hall. If such surface is present then it should be covered with sound absorbing materials.

When the sound waves fall on a surface it is reflected back, when the distance is more than 17 meters away. Sound is the reflected as individual repetition of direct sound. This reflection is called as an echo. Echo occurs due to the reflected sound waves which is common when the reflecting surface is curved. These echoes can be avoided by covering the surfaces with suitable absorbing material. Sound produced on the set of railings or staircase is heard as a musical note due to regular repeats of echoes of original sound.

Window panes, walls lacking rigidity and sections of wooden portions are thrown into vibrations which creates other sounds. For some audio the frequency of new NRG Acoustics SG-4 sound is same thus resulting in the resonance and such vibrations are called resonant vibration. Sound which irritates the ear or unwanted sound is called noise. Noises produced are three types: Inside noise, Air-borne noise, and structure borne noise which produces displeasing effect on the ear.