Module 2: Room Acoustics and Acoustical Defects Flashcards
The purpose of room acoustical design is ____, _____ and ______ of sound within a space.
to control the propagation, reflection and attenuation
Design goals of auditorium include:
Good Speech distinction
Design goals acc. to use of space:
Speech & Music
Design goals of an open plan office include:
Good speech privacy
T/F Room acoustical design does not equal to maximizing absorption
True
Angle of incidence = angle of reflection when (1) & (2)
- sound wavelength is adequately smaller than the dimensions of the object causing the reflection
- the reflecting surface is even (not sound scattering) and hard (not sound absorbing)
What shape of room have lateral reflections occur in the entire space?
Rectangle
What shape of room have reflections scatter and are directed mainly to the rear part of the space (not in the middle)?
Fan-shape
What shape of the room have reflections from concave surfaces cause sound to strongly focus on some parts of the space?
Round
Give six acoustical defects that may occur in a room: (EPrFeFsREn)
Echoes
Prolonged Reverberation
Flutter Echoes
Focused Sound
Resonance
Exterior noises
Sound reflected back to its source is ___.
An echo
The persistence of sound in the enclosed space, after the source of sound has stopped.
Reverberation
Long reverberation time (RT) due to large amounts of highly reflective surfaces and/or to large volume of space which will take considerable time for reflected sound to die out.
Prolonged Reverberation
The time which the sound persists is _____ of sound in the hall.
Reverberation time
Reverberation time is influenced by (3):
- Volume of the room
- Sound absorbing qualities of the room’s surfaces
- Number of people and furniture in the room.
Recommended reverberation time (in secs) for Excellent
0.50 to 1.50
Recommended reverberation time (in secs) for Very Bad
Above 5.0
A rapid buy repetitive succession of sounds caused by highly reflective parallel surfaces (wall to wall, ceiling to floor)
Flutter Echo
Is often heard as a high frequency ringing or buzzing.
Flutter
Caused by the concave surfaces which causes sound to converge at certain points with resulting loss of energy in other parts of the room.
Undue focused sound
The shape of the hall makes sound waves to concentrate in some particular areas of hall creating a sound of large quality.
These spots are ____.
Focused sound or sound foci
The emphasis of sound energy at a particular frequency.
Audio Resonance
_______ sound from vehicles, traffic engines, factories etc. may enter the hall either through the openings.
External Noises
How to remove external noise?
Open ended.
= This defect can be removed by proper planning of the hall with respect to its surroundings and by proper sound insulation of external walls
