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Acoustical parameters ISO 3382

Acoustical parameters ISO 3382. ISO 3382 acoustical parameters. 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. Schroeder ’ s BW Integration.

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Acoustical parameters ISO 3382

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  1. Acoustical parameters ISO 3382 Acoustical Parameters (ISO 3382)

  2. ISO 3382 acoustical parameters Acoustical Parameters (ISO 3382)

  3. 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 Acoustical Parameters (ISO 3382)

  4. Schroeder’s BW Integration Pressure Impulse Response Stationary Sound Decay (in dB) Energetic Impulse Response (in dB) Acoustical Parameters (ISO 3382)

  5. Reverberation time T20 Lp (dB) -5 dB 45 dB -25 dB Time (s) T20 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 TimeT20: extrapolated from -5 to -25 dB • Reverberation Time T30: extrapolated from -5 to -35 dB Acoustical Parameters (ISO 3382)

  7. Early – Late energy evaluation Useful Energy Detrimental Energy Acoustical Parameters (ISO 3382)

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

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

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

  11. Other acoustical parameters • Lateral Fraction: • LFC: 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) 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 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) 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 Acoustical Parameters (ISO 3382)

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

  17. Are IACC measurementsreproducible? • Diffuse field - hugedifferenceamong the 4 dummy heads Acoustical Parameters (ISO 3382)

  18. Are LF measurents reproducible? • Experiment performed in the Auditorium of Parma - sameloudspeaker, same source and receiver positions, 4 pressure-velocitymicrophones Acoustical Parameters (ISO 3382)

  19. Are LF measurentsreproducible? • At 7.5 m distance, the resultsalreadyexhibitsignificantscatter Acoustical Parameters (ISO 3382)

  20. Are LF measurentsreproducible? • At 25 m distance, the scatterisevenlarger Acoustical Parameters (ISO 3382)

  21. The Aurora Acoustical Parameters plugin Acoustical Parameters (ISO 3382)

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