Misura della risposta all

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Misura della risposta allimpulsoParametri
Acustici temporali e spaziali
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Informazioni estraibili dalla Risposta Impulsiva
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Alcuni Descrittori Acustici
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I parametri acustici (ISO 3382)

• Tempo di Riverberazione Iniziale (EDT)
  estrapolato da 0 a -10 dB
• Tempo di riverberazione T10 estrapolato da
  -5 a -15 dB
• Tempo di riverberazione T20 estrapolato da
  -5 a -25 dB
• Tempo di riverberazione T30 estrapolato da
  -5 a -35 dB

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I parametri acustici (ISO 3382)

• Indice di chiarezza C80 (musica sinfonica)

• Indice di chiarezza C50 (parlato)

Valore ottimale /- 1 dB
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I parametri acustici (ISO 3382)

• Indice di definizione D

• Tempo baricentrico TS

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I parametri acustici (ISO 3382)

• Strenght

• IACC

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I parametri acustici (ISO 3382)

• Lateral Fraction

• LFC

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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)
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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
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Lateral Fraction (LF) spatial parameter

• Another spatial parameter is the Lateral
  Fraction LF
• 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)
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Are binaural measurents reproducible?

• Experiment performed in anechoic room - same
  loudspeaker, same source and receiver positions,
  5 binaural dummy heads

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Are IACC measurents reproducible?

• Diffuse field - huge difference among the 4 dummy
  heads

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Are LF measurents reproducible?

• Experiment performed in the Auditorium of Parma -
  same loudspeaker, same source and receiver
  positions, 4 pressure-velocity microphones

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Are LF measurents reproducible?

• At 25 m distance, the scatter is really big

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Il plug-in Aurora Acoustical Parameters