Factors Affecting Architectural Acoustics 1.Reverberation Time • When the reverberation time is too high, the sound produced by the speaker will persist for a long period of time. • Similarly ,when the reverberation time is low, sound dies quickly and becomes inaudible in a short amount of time. • In order to improve the sound, reverberation time of a hall should be increased to an optimum value. Remedies :- • Decreasing total absorption coefficient of the wall • Placing sound reflection boards inside a hall 2. Loudness • Reverberation time of a hall is directly proportional to loudness. • Low loudness results in existence of sound for a shorter period while high loudness results in existence of sound for a longer period. • Therefore sound produced by the speaker should be within audible range. Remedies :- • Placing sound absorbing boards to reduce loundness • Placing sound reflecting boards to increase loudness. 3. Echelon Effect • Unwanted sounds are produced when people walk on staircase or floors o r hard paved paths due to poor finishing of the floor surface, structural effects, etc. • The above mentioned unwanted sound are termed as ‘echelon effect’ . Remedies :- • Finishing the floors or stairs very finely. • Using carpet to caver floors and stairs.. 4. Structure-Borne Sound • Sound waves generated inside a hall are known as structure-borne sound. • They are produced due to apparent motion of benches & footsteps & propagated through walls and floors. Remedies :- • Using rigid structures so as to rest the vibrations. • Introducing discontinuities in the path of sound. • Converting floor and ceilings with suitable sound absorbing materials & anti-vibration mouths.. 5. Echo • If the time interval between direct sound and reflected sound is less than 1/15 of a second, the reflected sound is helpful in incresing loudness. • But if the time interval is less than that, then the sound arrives later and will cause confusion. Remedies :- • To prevent unnecessary reflection of sound. • Covering long distance walls and ceilings with suitable sound absorbing materials.. 6. Focusing due to walls and ceilings • Sound produced by speaker undergoes multiple reflections at ceilings and walls. • Reflected sounds from ceilings and walls should not be focused on particular point, rather it should be distributed throughout a hall. • Generally a plane surface reflects sound uniformly but a curved surface does not. So reflection of sound from a curved surface produces a harmful effect. Remedies :- • Radius of curvature of

ceilimg should be kept twice the height of the building • Distribution of sound waves from a concave surface should be made uniform. 7. Resonance within a building • Sound waves get amplifies when the frequency of vibration of air particles matches with the hall’s natural frequency of vibration. • Thus, it results in an unwanted sound effect in side a hall. Remedies :- • Model-Hall or a model auditoriun should be kept inside a vessel which contains water. • The water-wave particle movememnts are studies and are used for the construction of actual hall or auditorium.