Module 2: Room Acoustics and Acoustical Defects

Question 1

The purpose of room acoustical design is ____, _____ and ______ of sound within a space.

Answer 1

to control the propagation, reflection and attenuation

Question 2

Design goals of auditorium include:

Answer 2

Good Speech distinction

Question 3

Design goals acc. to use of space:

Answer 3

Speech & Music

Question 4

Design goals of an open plan office include:

Answer 4

Good speech privacy

Question 5

T/F Room acoustical design does not equal to maximizing absorption

Answer 5

True

Question 6

Angle of incidence = angle of reflection when (1) & (2)

Answer 6

1. sound wavelength is adequately smaller than the dimensions of the object causing the reflection
2. the reflecting surface is even (not sound scattering) and hard (not sound absorbing)

Question 7

What shape of room have lateral reflections occur in the entire space?

Answer 7

Rectangle

Question 8

What shape of room have reflections scatter and are directed mainly to the rear part of the space (not in the middle)?

Answer 8

Fan-shape

Question 9

What shape of the room have reflections from concave surfaces cause sound to strongly focus on some parts of the space?

Answer 9

Round

Question 10

Give six acoustical defects that may occur in a room: (EPrFeFsREn)

Answer 10

Echoes
Prolonged Reverberation
Flutter Echoes
Focused Sound
Resonance
Exterior noises

Question 11

Sound reflected back to its source is ___.

Answer 11

An echo

Question 12

The persistence of sound in the enclosed space, after the source of sound has stopped.

Answer 12

Reverberation

Question 13

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.

Answer 13

Prolonged Reverberation

Question 14

The time which the sound persists is _____ of sound in the hall.

Answer 14

Reverberation time

Question 15

Reverberation time is influenced by (3):

Answer 15

1. Volume of the room
2. Sound absorbing qualities of the room’s surfaces
3. Number of people and furniture in the room.

Question 16

Recommended reverberation time (in secs) for Excellent

Answer 16

0.50 to 1.50

Question 17

Recommended reverberation time (in secs) for Very Bad

Answer 17

Above 5.0

Question 18

A rapid buy repetitive succession of sounds caused by highly reflective parallel surfaces (wall to wall, ceiling to floor)

Answer 18

Flutter Echo

Question 19

Is often heard as a high frequency ringing or buzzing.

Answer 19

Flutter

Question 20

Caused by the concave surfaces which causes sound to converge at certain points with resulting loss of energy in other parts of the room.

Answer 20

Undue focused sound

Question 21

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 ____.

Answer 21

Focused sound or sound foci

Question 22

The emphasis of sound energy at a particular frequency.

Answer 22

Audio Resonance

Question 23

_______ sound from vehicles, traffic engines, factories etc. may enter the hall either through the openings.

Answer 23

External Noises

Question 24

How to remove external noise?

Answer 24

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