| |
| |
What
are "good acoustics"? |
|
| |
It
is generally not easy to say what constitutes "good acoustics".
Firstly,everything depends on what the room is intended to be used
for. The acoustical requirements are not the same for a concert hall,
a theatre or a lecture room, and when the same hall has to be used
both for concerts and theatre performances, some compromises have
to be made.
Secondly, it depends on how the acoustics of the room are defined.
An acoustician will talk about reverberation time, sound distribution,
absorption which we called objective parameters that is possible to
measure. Someone listening to a piece of music or watching a movie
in the room will describe the acoustics in terms of definition, clarity
of tone, warmth etc. These parameters which may be subjective or difficult
to measure. Hence, the concept of "good acoustics" consists
of a combination of both the objective as well as subjective parameters.
|
| |
Behaviour
of Sound in a Room |
|
| |
A
knowledge of the behaviour of sound in a room is necessary if we wish
to adapt the room for speech or music and if we wish to insulate against
external noise.
Consider the effect of placing a sound source in a room. When sound
energy from the source strikes a room boundary, the reflected sound
energy contributes to the sound-field in the room, the absorbed sound
dissipates as heat and the transmitted sound energy propagates away
through the boundary layer. |
 |
| |
Absorption
of Sound in a Room |
|
| |
We
can understand the effect of absorption by measuring, at a given position
in a room, the sound pressure level caused by a steady sound power
source. If more absorption material is put in the room, the sound
pressure level is less because the energy in the reflections is reduced.
Typical absorbing surfaces in a room include ceiling boards, sofas
and curtains. These are simple porous absorbers which absorb sound
energy. |
 |
| |
By
controlling the proportions of the absorbers in the room, it is possible
to adjust the warmth of a room for music, or its clarity for speech. |
|