Simulation Near Eardrum(1989)

Ref: "Headphone simulation of free-field listening. I: Stimulus synthesis",

Frederic L. Wightman, Doris J. Kistler, pp. 858-865, J. Accoust. Soc. Am., 85(2), February 1989.

• Goal: Given x1(t), produce x2(t) s.t. y2(t) equals to y1(t)

      -x1(t): electrical signal from a loudspeaker
      -x2(t): electrical signal from a earphone
      -y1(t): resultant electrical signal at eardrum from x1(t)
      -y2(t): resultant electrical signal at eardrum from x2(t)



• Fourier Transform: Y1 = X1 L F M

      -L: Loudspeaker trasfer function
      -F: the free-field-to-eardrum transfer function(Head
          Related Transfer Function, HRTF)
      -M: microphone transfer function
            Y2 = X2HM
      -H: headphone-to-eardrum transfer function

  Y2 = X2 H M

  let Y1 = Y2, 

     X2 = X1 L F/H

    desired filter transfer function T = L F/H.

  measurements were made at all elevations except +72 

  and + 90 deg, and at all azimuths around the circle in 15-deg steps.

  Thus transfer functions were measured from both ears at 144 source positions.

  10 subjects were measured.

Active Localization of Visual Sound(1990)

• Goal:

      - to achieve effective localization of virtual sounds that
        would enable an observer to walk quickly and 
        effortlessly to thposition of a simulated sound.
      - see fig.1



• approximation

• head shadow

      - crossover frequence 1.8kHz
      - sinusoidally s.t. Left is attenuated 16dB to Right at 90 deg



• Pinnae shadow

      - azimuth = 0, minimum
      - azimuth = 180, maximum 3dB