This document discusses factors that affect architectural acoustics, including reverberation time, loudness, echo effects, structure-borne sound, focusing of sound waves, and resonance. It explains how each factor impacts sound quality and lists remedies such as using sound absorbing or reflecting materials on walls and ceilings to optimize reverberation time and loudness or prevent echoes and focusing of sound waves. Modeling acoustic effects in a water tank can help design actual halls to avoid unwanted resonance.

1. Architectural Acoustics
• 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. 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. 3. Echelon Effect
• Unwanted sounds are produced when people walk on
staircase or floors or 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. 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. 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. 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. 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.