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

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B5: Dichotic presentation of the artificial head signals, which have been recorded
without the pinnae of the artificial head
B6: Dichotic presentation of the microphone signals, which have been recorded
without the head and pinnae of the artificial head
When presented over headphones, the test signals A1 … A4 and B1 … B6 create
more or less stable phantom sources. To give an example, depending on the accuracy
of the recording and playback stages, Signal A1 should produce an easily localisable
phantom source, whilst Signal B2 will certainly result in a poor reproduction. In order
to be able to compare these scenarios to the localisation conditions applicable to a real
sound source, three other test signals are also included:
Group C:
No phantom source situation, but a loudspeaker positioned in the median plane. The
following reproduction scenarios are chosen:
C1: Otherwise as A1
C2: Instead of the pivoting movement, the artificial head is rotated by δ ± 30°
C3: As C2, but diotic presentation of one artificial head signal
Using headphones, each test signal is presented to the subjects twice. For each
presentation, the auditory event (produced by the associated test signal) has to be
evaluated in terms of one attribute of detectability, i.e. the detectability of sound
colour changes (Attribute Kl) or the detectability of directional changes (Attribute
Ri). A 5-point rating scale is used:
0: not detectable
0.25: just about detectable
0.5: detectable
0.75: clearly detectable
1: very clearly detectable
Before each trial, the subjects are presented with a few test examples. This helps
improve judgement consistency and prevents learning effects during the actual
listening test. During this training phase, the subjects’ attention is drawn either to
Attribute Kl or Attribute Ri. For 11 participants this happens first for Kl, whilst 11
other participants are asked to evaluate Ri first.
Listening test results
1. The relationship between the attributes Kl and Ri for the test signal groups A
and B is evident from Figure 7. Each included Kl/Ri-value constitutes the
arithmetic mean of the verdicts of 11 subjects for one test signal (four mean