1. Acoustical parameters ISO 3382
16 November 2012
Acoustical Parameters (ISO 3382)

2. ISO 3382 acoustical parameters
09/13/2003
ISO 3382 acoustical parameters
16 November 2012
Acoustical Parameters (ISO 3382)
AES 115th Convention - New York, NY

3. From Impulse Response to Sound Decay
09/13/2003
From Impulse Response to Sound Decay
Schroeder’s backward integral
Makes it possible to reconstruct the decay of a stationary source by backward integration of the measured impulse response
16 November 2012
Acoustical Parameters (ISO 3382)
AES 115th Convention - New York, NY

4. Schroeder’s BW Integration
09/13/2003
Schroeder’s BW Integration
Pressure Impulse Response
Stationary Sound Decay (in dB)
Energetic Impulse Response (in dB)
16 November 2012
Acoustical Parameters (ISO 3382)
AES 115th Convention - New York, NY

5. Acoustical Parameters (ISO 3382)
Reverberation time T20
Lp (dB)
-5 dB
45 dB
-25 dB
Time (s)
T20
16 November 2012
Acoustical Parameters (ISO 3382)

6. ISO 3382 Reverberation Time(s)
Early Decay Time (EDT): extrapolated from 0 to -10 dB
Reverberation Time T10: extrapolated from -5 to -15 dB
Reverberation Time T20: extrapolated from -5 to -25 dB
Reverberation Time T30: extrapolated from -5 to -35 dB
16 November 2012
Acoustical Parameters (ISO 3382)

7. Early – Late energy evaluation
09/13/2003
Useful Energy
Detrimental Energy
16 November 2012
Acoustical Parameters (ISO 3382)
AES 115th Convention - New York, NY

8. Early-Late parameters
Clarity Index C80 (symphonic music):
Optimal Value = +/- 1 dB
Clarity Index C50 (speech):
Optimal Value = +/- 1 dB
16 November 2012
Acoustical Parameters (ISO 3382)

9. Early-Late parameters
Definition Index D:
Center Time tS:
16 November 2012
Acoustical Parameters (ISO 3382)

10. Other acoustical parameters
SPL at 10 m
Strenght:
IACC:
16 November 2012
Acoustical Parameters (ISO 3382)

11. Other acoustical parameters
Lateral Fraction:
LFC:
16 November 2012
Acoustical Parameters (ISO 3382)

12. Spatial analysis by directive impulse responses
The initial approach was to use directive microphones for gathering some information about the spatial properties of the sound field “as perceived by the listener”
Two apparently different approaches emerged: binaural dummy heads and pressure-velocity microphones:
Binaural microphone (left)
and
Pressure-velocity microphone (right)
16 November 2012
Acoustical Parameters (ISO 3382)

13. IACC “objective” spatial parameter
It was attempted to “quantify” the “spatiality” of a room by means of “objective” parameters, based on 2-channels impulse responses measured with directive microphones
The most famous “spatial” parameter is IACC (Inter Aural Cross Correlation), based on binaural IR measurements
Left
pL(t)
Right
pR(t)
80 ms
16 November 2012
Acoustical Parameters (ISO 3382)

14. Lateral Fraction (LF) spatial parameter
Another “spatial” parameter is the Lateral Fraction JLF
This is defined from a 2-channels impulse response, the first channel is a standard omni microphone, the second channel is a “figure-of-eight” microphone:
Omni
ho(t)
Figure of 8
h8(t)
16 November 2012
Acoustical Parameters (ISO 3382)

15. Are binaural measurents reproducible?
Experiment performed in anechoic room - same loudspeaker, same source and receiver positions, 5 binaural dummy heads
16 November 2012
Acoustical Parameters (ISO 3382)

16. Are IACC measurements reproducible?
90° incidence - at low frequency IACC is almost 1, at high frequency the difference between the heads becomes evident
16 November 2012
Acoustical Parameters (ISO 3382)

17. Are IACC measurements reproducible?
Diffuse field - huge difference among the 4 dummy heads
16 November 2012
Acoustical Parameters (ISO 3382)

18. Are LF measurents reproducible?
Experiment performed in the Auditorium of Parma - same loudspeaker, same source and receiver positions, 4 pressure-velocity microphones
16 November 2012
Acoustical Parameters (ISO 3382)

19. Are LF measurents reproducible?
At 7.5 m distance, the results already exhibit significant scatter
16 November 2012
Acoustical Parameters (ISO 3382)

20. Are LF measurents reproducible?
At 25 m distance, the scatter is even larger
16 November 2012
Acoustical Parameters (ISO 3382)

21. The Aurora Acoustical Parameters plugin
16 November 2012
Acoustical Parameters (ISO 3382)