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Room Absorption Sound

Reference data and engineering information about room absorption sound for acoustics applications.

roomabsorptionsound

Overview

Engineering reference data for Room Absorption Sound in acoustics.

Key Formulas

Speed of Sound

c=γRTc = \sqrt{\gamma R T}

Speed of sound in an ideal gas.

Sound Level

L=10log10(I/I0)L = 10 \log_{10}(I/I_0)

Decibel level.

Wavelength

λ=c/f\lambda = c / f

Wavelength = speed / frequency.

Variables

SymbolDescriptionUnit
ccSpeed of soundm/s
LLSound leveldB
λ\lambdaWavelengthm
ffFrequencyHz

Room Absorption Characteristics Table

The following table summarizes room characteristics, typical reverberation time ranges, and mean sound absorption coefficients for different room types.

5 rows
Mean sound absorption coefficients and reverberation times for typical room characteristics
Room Characteristic
Reverberation Time Range (Ta)
Typical Rooms
Mean Absorption Coefficient (αm)(-)
Very Soft0.2 < Ta < 0.25Radio & TV studio0.4
Soft0.4 < Ta < 0.5Restaurant Theater Lecture hall0.25
Normal0.9 < Ta < 1.1Office Library Flat0.15
Hard1.8 < Ta < 2.2Hospital Church0.1
Very Hard2.5 < Ta < 4.5Large church Factory0.05

Source: engineeringtoolbox.com

Mean Sound Absorption Coefficient Calculation

For more accurate values, the mean sound absorption coefficient (αm\alpha_m) should be calculated using the weighted average of individual surface absorption coefficients:

αm=i=1nαiSii=1nSi\alpha_m = \frac{\sum_{i=1}^{n} \alpha_i S_i}{\sum_{i=1}^{n} S_i}

Where:

  • αi\alpha_i is the sound absorption coefficient for surface ii,
  • SiS_i is the area of surface ii,
  • nn is the total number of surfaces.

This coefficient directly influences reverberation time (TaT_a), with higher αm\alpha_m leading to shorter reverberation times and a softer acoustic environment. Use the table above for quick reference or the formula for detailed room analysis.

Interactive Charts

Sound Room Absorption

References