Hi Bruno,
Thanks for the detailed explanation. Did your participants rate the
slower rate stimuli as more regular, or the faster ones?
The faster ones were rated more regular.
In any case, the problem with your stimuli may be that they were
all fairly irregular,
Correct, but this, I find, is exactly what happens in speech. My
primary interest is not to investigate how subjects perceive
irregularity of intervals in general but how they perceive the
irregularity differences of c and v intervals typically occurring in
different languages.
so participants may have relied on rate because it was a much more
salient property.
Correct as well, and, again, I assume that this may be the case in speech too.
You may have to prevent this by giving more precise instructions
and/or controlling the rate of your stimuli.
Well, it has been shown already that when subjects are trained on
the stimuli and when rate is controlled for they can use variability
cues without a problem. I deliberately left the interpretation of
'regularity' to my subjects and claim that when they have the choice
they choose rate rather than interval variability (or rather: the
degree of interval variability occurring in speech) to decide
whether a sequence of variable intervals is more or less regular.
Again, if listeners should use these cues in real situations to
distinguish between languages nobody will tell them which cues to
listen for and speech rate will not be normalized.
It seems unlikely to me that linguists' classification of languages
as stress- or syllable-timed merely reflects a difference in the
average speaking rate for those languages.
Well, generally this is my idea. I would not go as far as saying
that it 'merely' reflects speech rate, but I do claim that speech
rate, amongst other factors, plays a major role in there which has
so far been entirely neglected. I am currently running experiments
with delexicalised stimuli that are closer to real speech (low pass
filtered speech at 300 Hz) and I am manipulating the rates of
stimuli in order to test whether I can make listeners rate German
stimuli as French based on rate only.
Best wishes,
Volker
Best,
Bruno
Hi Bruno,
I don't think there are any data suggesting that people cannot
distinguish interval durations at fast rates. The question is how
large the differences must be to be detected, and how the
magnitude of that difference depends on rate. There is no
"breakdown" of discrimination at any rate.
Yes, thanks for pointing that out so clearly. After reading through the
literature this morning I realized that I got something wrong there...
It is unclear what your listeners had to do. You are talking about "a
big effect of rate on listeners' perception of speech rhythm",
but what does this have to do with interval discrimination? What
exactly
was the effect of rate on perceived speech rhythm, and how did
interval durations vary?
Well, sorry, it was indeed vague. I was not sure to what level of
detail readers on this list would be interested in this. I was
referring to recent theories of speech rhythm claiming that rhythm
classes (e.g. stress- and syllable-timed languages) can be
distinguished by the listener based on the durational variability
of consonantal (c) and vocalic (v) intervals (e.g. work by Frank
Ramus or Esther Grabe). It was
demonstrated that syllable-timed languages for example have
proportionally less c- and v-interval variability than
stress-timed languages and that this information is processed by
the listener to group languages into traditional rhythmic classes.
For two syllable-timed (French & Italian; F & I) and two
stress-timed languages (English & German; E & G) my own data
replicates the objective differences nicely. However, I found that
because of their less complex syllable structure, speakers of
syllable-timed languages also produce cv-intervals at a far higher
rate than stress-timed languages.
In a perception experiment I took sentences from French and German
and turned v-intervals into tones and c-intervals into white noise
and asked listeners to rate the stimuli according to the
'regularity of beep sequences' on a scale form 1 to 10. I left the
interpretation of 'regularity' to the listener and expected that
listeners would pick up on the proportionally higher c- and
v-interval variability in German and thus rate these stimuli as
the more irregular beep sequences. However, results showed very
poor correlation between the regularity rating and any of a number
of c- and v-variability measures but I found a strong correlation
with cv-rate. So it seems that in my experiment listeners
interpreted 'regularity' as rate only and did not listen for any
durational variability within the stimuli.
In order to interpret the results I thought it may help to consult work
that looked at the influence of rate on interval variability
perception. However, I find my data and method are pretty
difficult to compare with Friberg & Sundberg and the type of
studies mentioned in there. If I had pointed out to my listeners
to listen out for certain types of durational variability I am
sure they could have done it (Ramus showed that in a way by not
allowing rate variability). However, the fact that they do not
make use of durational variability cues when given the choice
between rate and variability tells me that this may be something
they do in speech too when they distinguish between languages
based on rhythmic cues.
Hope that makes it clearer,
Volker
Best, Bruno
Bruno and Pierre,
thank you so much for your helpful suggestions!
The work on rhythm is more what I am looking for. I found a big
effect of rate on listeners' perception of speech rhythm. I
assume
that it may have something to do with listeners not being able to
detect interval variability in speech any more when the intervals
under investigation are shorter (typically the case in so
called 'syllable-timed languages' because they posses simpler
phonotactic
structures). So I am looking for evidence showing at what rate
interval distinction ability breaks down in rhythmic contexts.
However, all interval durations I am looking at (syllables, c-
or v-intervals) are well below 200 ms in any language I have
collected
data on, which, judged by the rhythm findings, would mean that
listeners should not be able to detect durational variability at
all between any of the speech intervals (when judging duration
only!) and that can hardly be true. It probably has to do with
the
fact that interval variability in my speech stimuli is much
more complex and do not fulfill the criterion of isochrony in
the way they do it in the Friberg & Sundberg study. I am working
on an explanation...
Best wishes & thanks again, Volker
-- -------------------------------------------- Volker Dellwo
Department of Phonetics & Linguistics University College London
phone: +44 (0)20 7679 5003 (internal: 25003)
www.phon.ucl.ac.uk www.phonetiklabor.de
--------------------------------------------
--
--------------------------------------------
Volker Dellwo
Department of Phonetics & Linguistics
University College London
phone: +44 (0)20 7679 5003 (internal: 25003)
www.phon.ucl.ac.uk
www.phonetiklabor.de
--------------------------------------------
--
--------------------------------------------
Volker Dellwo
Department of Phonetics & Linguistics
University College London
phone: +44 (0)20 7679 5003 (internal: 25003)
www.phon.ucl.ac.uk
www.phonetiklabor.de
--------------------------------------------