Acoustics of Concert Halls and Rooms

SOME BASICS OF ARCHITECTURAL ACOUSTICS

Auditorium Acoustics

Science of Sound, Chapter 23Principles of Vibration and Sound,

Chapter 11Kimmel Center

Free field

Reflections

p vs r log p vs log r

SOUND FIELD

Sound decay

Sound decay in a400 m3 classroom

Sound pressure level as a function of time for that room

GROWTH AND DECAY OF REVERBERANT SOUND

RT = K (volume / area)RT = 0.161 V/A (V in m3; A in m2 )If room dimensions are given in feet, the formula may be written:RT= 0.049 V/A (V in ft.3 ; A in ft.2 )

Decay of reverberant sound

(a) and (b) are decay curves of sound pressure and soundlevel in a room with uniform energy distribution(c) shows different initial and final reverberation times(d) shows peaks due to prominent standing waves or roomresonances

CALCULATING REVERBERATION TIME

CALCULATING REVERBERATION TIME

Desirable reverberation times

for various sizes and functions

Variation of reverberation time with frequency in

good halls

McDermottConcert

Hall(Dallas)

Orchestra Hall

(Chicago)

MeyerhofSymphony

Hall(Baltimore)

Walt Disney Concert Hall

Disney

KimmelCenterAuditorium

BACKGROUND NOISE CRITERIA

• Spatial impression• Intimacy• Early decay time• Clarity• “Warmth”

Important criteria for concert halls:

Concerthalls

throughoutthe

World