Bregman (1994) - Chapter 2 (47 - Flashcards
Auditory stream segregation vs. streaming effect
- general mechanism in auditory scene analysis, which forms streams
- effect when a sequence of high and low tones is grouped into two different streams
Can the streaming effect override the true sequence of sounds?
yes
Trill threshold: who? what?
Geroge Miller 1947:
apparent motion between two frequencies unless they are two far apart. (fixed tempo)
the breaking point = trill threshold
What did Bozzi and Vicaroi add to the auditory stream segregation?
distances are relative to other distances
Four advantages of using looped sounds:
- Aspects can be changed, whereas everthing else stays constant.
- Low influence of starting and ending point.
- repetition pushes levels of stream segregation to above normal levels.
- Loops eliminate the use of slow cognitive strategies by the listener.
Five methods to measure stream segregation:
- Method of adjustment
- method of limits
- proportion of time integration and segregation
- rating scale for fixed presentation
- pattern recognition
Another four methods to measure stream segregation:
- rhythm changes
- drawing
- judgement of order
- counting tones
Hysteresis?
Once the sequence is heard as integrated and the listeners start to increase the frequency separation again, it may require a large separation to split the sequence. The threshold between the two percepts can be so unstable as a result of this hysteresis that the thresholds are very unreliable.
What was the main finding of Leo van Noorden’s thesis?
There is an area in which participants can choose between hearing stimulus as one or two streams.
What are the names of the limits of the area of both possibilities?
Temporal Coherence Boundary (TCB) Fission Boundary (FB)
FB
Fission Boundary:
streams to close to be heard seperately
TCB
Temporal Coherence Boundary:
frequency separation too large to be heard as one stream
Which boundary is sensitive to tone rate?
Temporal Coherence Boundary
Another important fact van Noorden’s study showed:
Segregation seems to be the same whether the variable tone is above or below the fixed tone in frequency when the results are plotted on a semitone scale.
Frequency and loudness in segregation?
Frequency dominates over loudness at high speeds.
Frequency separation displays a simple relation to segregation when plotted on a ..
.. logarithmic scale.
When the rate of tones becomes higher the streaming phenomenon becomes ..
.. stronger.
How many possible time-intervals between tones are there?
A: onset - onset inter-streams
B: offset - onset inter-streams
C: onset - onset intra-stream
D: offset - onset intra-stream
Which time-intervals should be important for gestaltists?
B and D -> like the spaceing between objects
Which time-intervals should be important if rhythm is important?
A and C -> as onsets define rhythm
And which are the most important time-intervals after all? probably
B and D, but not sure. Hard to maipulate independently.
Are onsets clearly defined?
No
Hirsch and Warren agree on?
Both authors agree, then, that we deal with rapid sequences of speech sounds by recognizing units that are larger than the phoneme.
What’s the phenomenon that binds rapidly occurring events to one single tone?
Unitization
Royer and Robin
Intensity and unitization?
Apparently, abrupt rises in intensity tell the auditory system that a new sound has joined the mixture and that it should begin the analysis of a new unit.
What’s the jump sensation?
These observations, like those of Royer and Robin, seem to indicate that silent gaps of sufficient duration will cause sound to segregate into separate units, but even at the point where they just separate, there will still be strong perceptual relations between them (the jump sensation).
If stream formation segregate groups in frequency, what is it that segregates groups in time?
unit formation
Roger Shepard’s notion of psychophysical complementarity and location:
space physically is a continuum so it should also be one mentally.
One might suppose that the reason that vision and touch represent space in an analog fashion is that in both modalities, the representations of space at the surface receptors and in the primary sensory cortex take the form of a topographical map. It seems, however, that audition is different.
What is laid out like a map for audition?
Frequency
On which level can we find topographical organization of sounds?
higher levels: superior colliculus (especially in bats)
Psychophysical complementarity, location and sound:
Experiment by Gillian Rhodes:
nine loudspeakers, blindfolded, where does the sound come from?
distance matches RTs
maybe only label effect? counting how many speakers in bewteen?
Location seems to play a role in stream segregation, but
humans don’t seem to trust it blindly, eg:
While spatial location is used, it by no means overpowers other bases for grouping when in conflict with them. That is why humans can segregate different voices even when they hear them coming over a monophonic radio.
dichotic
simultaneous stimulation of the right and left ear by different sounds
diotic
simultaneous stimulation of the right and left ear by the same sounds
