Longer Reverberation for Lows

It is a common experience for more distant listeners to music to conclude that it is deficient in bass. This bass problem is a characteristic of the ear since the ear shows progressively greater discrimination against low frequencies as the sound gets softer.

This problem can be partially overcome by designing the auditorium so that its reverberation time for low frequencies is greater than that for high frequencies. This gives a natural-sounding bass boost to sound in the rear of an auditorium. Actually, the longer reverberation time for lows usually happens naturally, particularly if a lot of wood is used in the construction since wood absorbs high frequencies more than lows. However, some construction types selectively absorb low frequencies and are to be avoided in music-making areas. Typical thin wood paneling on studs selectively absorbs low frequencies and thus should be avoided in auditoriums.

Architectural contributions to good acoustics
Auditorium examples
Index

Auditorium acoustics
 
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Longer Reverberation Time for Lows

The graph shows a progression to higher reverberation times for low frequencies. It is typical for the reverberation time for low frequencies for a good auditorium to be some 30% higher than the overall average reverberation time. This characteristic helps to deal with the bass loss problem, one of the fundamental problems of auditorium acoustics.

Further discussionAuditorium examples
Index

Auditorium acoustics

Reference
Backus
Ch 9
 
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Auditorium Examples

The auditoriums cited below are some of the most outstanding in the world, and they show the consistent pattern of having significantly longer reverberation times for low frequencies. The first column is a measurement of the delay time between direct sound and the first reflected sound, which has been associated with a feeling of "presence" or "intimacy" as perceived by the listener.

Auditorium
t1(floor, ms)
RT(125Hz)
RT(500 Hz)
RT(2000 Hz)
Symphony Hall, Boston
15
2.2
1.8
1.7
Orchestra Hall, Chicago
40
...
1.3
...
Severance Hall, Cleveland
20
...
1.7
1.6
Carnegie Hall, New York
23
1.8
1.8
1.6
Opera House, San Francisco
51
...
1.7
...
Arie Crown Theatre, Chicago
36
2.2
1.7
1.4
Royal Festival Hall, London
34
1.4
1.5
1.4
Royal Albert Hall, London
65
3.4
2.6
2.2
Concertgebouw, Amsterdam
21
2.2
2.1
1.8
Kennedy Center, Washington
...
2.5
2.2
1.9
See also White & White, p375 for table of opera houses and auditoriums.
Reverberation timeLonger reverberation time for lows
Index

Auditorium acoustics

References
Rossing
Science of Sound
Ch 23

Beranek
 
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