on the localisation in the superimposed soundfield - Hauptmikrofon ...

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12 2.2.1 Measurement of the comb filter effect An artificial head (NEUMANN KU 80) is set up at the listening position of a conventional stereo layout (see Figure 1). The levels of the frequency bands (see ZWICKER / FELDKELLER 1967) of the artificial head signals in-between 0.25 and 6 kHz are measured as a function of the time delay ∆t between the loudspeaker signals. The time delays ∆t = 0, 90, 210, 270 and 480 µs are achieved by displacing the artificial head by 0 to 16 cm to the right. This corresponds to a shift in phantom source direction from Φ = 0° ... +25°. The occurring level changes are negligible. The results are shown in Figure 4. left ear right ear Figure 4: Comb filter effect for time-based stereophony, see text (the auditory event shifts to the right))
13 The measurements display the spectral changes that result at the left ear when switching on Loudspeaker B (i.e. the right loudspeaker) and the spectral changes that result at the right ear when switching on Loudspeaker A (i.e. the left loudspeaker). The transfer functions of the entire ‘loudspeaker - outer ear - microphone’ set-up have been eliminated. The inserted arrows mark those frequencies at which, from a calculational viewpoint, one would expect there to be a trough if one assumes that the interaural time differences are frequency-independent (τ A - τ B ≈ 250 µs for Ω A = Ω B = 30°). Looking at these measurements, the following observations can be made: 1. The troughs are in the order of 10 dB or more. The boosts, especially at low frequencies, often amount to 5 dB. At mid frequencies spectral differences of about 15 dB occur, whilst at high frequencies this value is somewhat reduced due to the greater attenuation of the crosstalk components. 2. The troughs’ locations in the frequency spectrum are only “ear-symmetrical” for ∆t = 0, i.e. if ∆t is increased up to 250 µs, the troughs will shift to the high frequencies at one ear and to the low frequencies at the other ear. For ∆t up to 250 µs, the time delay resulting at one ear equals zero (in this case the left ear, which does not ‘face’ the phantom source). For ∆t > 250 µs, the troughs appear at progressively lower frequencies at both ears. Figure 5: The mean values of the resultant spectra at the ears, taken from Figure 4
Page 1 and 2: 1 ON THE LOCALISATION IN THE SUPERI
Page 3 and 4: 3 Abstract Theile, Günther On the
Page 5 and 6: 5 references as well as WETTSCHUREC
Page 7 and 8: 7 spatial information. Depending on
Page 9 and 10: 9 sources. As already indicated abo
Page 11: 11 This “spectral objection” re
Page 15 and 16: 15 respective interaural transfer f
Page 17 and 18: 17 values per test signal). The two
Page 19 and 20: 19 binaural monaural Figure 9: Resu
Page 21 and 22: 21 3. An association model for the
Page 23 and 24: 23 3.1 The localisation stimulus se
Page 25 and 26: 25 1. The direction of an auditory
Page 27 and 28: 27 information patterns due to inpu
Page 29 and 30: 29 (agnosia). For humans, agnosia c
Page 31 and 32: 31 nonlinear classification e.g. ma
Page 33 and 34: 33 other specific systems (visual,
Page 35 and 36: 35 simplified case of the interaura
Page 37 and 38: 37 4. The localisation process in t
Page 39 and 40: 39 Bild 19 : Auto-correlation funct
Page 41 and 42: 41 1. For a given bandwidth ∆f, t
Page 43 and 44: 43 For informal verification purpos
Page 45 and 46: 45 Therefore, the suppression of so
Page 47 and 48: 47 In the phantom source situation,
Page 49 and 50: 49 the direction of the auditory ev
Page 51 and 52: 51 4.3.1 The “law of the first lo
Page 53 and 54: 53 Particular support for the assum
Page 55 and 56: 55 location and a gestalt associati
Page 57 and 58: 57 produce the same spatial propert
Page 59 and 60: 59 process, can be investigated by
Page 61 and 62: 61 level decrease signal delay sign
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63 It seems that the first part was
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65 3) The “cocktail party effect
Page 67 and 68:
67 de BOER, K. (1940): Plastische K
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69 GARDNER, M. (1973): Some single-
Page 71 and 72:
71 MASSARO, D., WARNER, D. (1977):
Page 73:
73 THEILE, G. (1978): Weshalb ist d
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