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21.05.2011 Oliver Niebuhr 1
Analysis of Spoken Languageat the Dept. of General Linguistics Christian-Albrechts-Universität zu Kiel
Oliver Niebuhr
On the Domain of Auditory Resoration in Speech
European Conference on Cognitive Science
New Bulgarian University, Sofia21st May 2011
21.05.2011 Oliver Niebuhr 2
Analysis of Spoken Languageat the Dept. of General Linguistics Christian-Albrechts-Universität zu Kiel
• Series of experiments with an explicit focus on the perception of „sound segments“, starting with Warren (1970).
• Speech stimuli in which sound segments were replaced by noise or silence.
• „auditory scene analysis involves a grouping of sounds. The principal of similarity of very important“
• Finding: When the noise is suitable to be interpreted by the listeners as a masker of the speech signal, the missing sound segments are added in perception. An intact speech utterance is heard in addition to a noise pattern
Phonemic restoration
Background
Bregman (1990)
21.05.2011 Oliver Niebuhr 3
Analysis of Spoken Languageat the Dept. of General Linguistics Christian-Albrechts-Universität zu Kiel
• The notion of phonemic restoration was applied to connected speech…
• …based on the following concept that is reflected in the term „speech reduction“ = phonological information is lost
Background
//
[]String of modified sound segments
In speech comprehension, the
deleted phonemes or phonemic
features are perceptually restored
?
21.05.2011 Oliver Niebuhr 4
Analysis of Spoken Languageat the Dept. of General Linguistics Christian-Albrechts-Universität zu Kiel
• However, this phoneme-centered view is oversimplified. A growing body of evidence shows that connected-speech
processes are overall rather a non-linear reorganization than a deletion or „reduction“ of essential sound features.
• „The process stops where words are still distinct“ (Kohler 1990), i.e. the meaning-bearing word may be a better reference unit than the meaning-differentiating phoneme.
• Subtle “phonetic essences” of words remain even after a strong “de-segmentalization”, but these essences fall between the cracks of a phonemic perspective
Background
21.05.2011 Oliver Niebuhr 5
Analysis of Spoken Languageat the Dept. of General Linguistics Christian-Albrechts-Universität zu Kiel
Background
122ms, 72.8dB
90ms, 78.9dB
„Voss Shombdon“, /s/
„Vosh Shombdon“, //
(Niebuhr, 2009, 2011)
• The imprint of /s/ in the preceding vowel remains after /s/ assimilation
21.05.2011 Oliver Niebuhr 6
Analysis of Spoken Languageat the Dept. of General Linguistics Christian-Albrechts-Universität zu Kiel
Background
/n/ of „kann“ is verylong, palatal [] and has two E-max
[k] is producedas palatalized []
the two /a/are frontedand soundlike []
(Kohler and Niebuhr, 2011)
• Reorganization of the phonetic essence of German „Ihnen“ (you)
• (a) „Ich kann das ja mal sagen“• (b) „Ich kann Ihnen das ja mal sagen“• (I can mention this to you)
21.05.2011 Oliver Niebuhr 7
Analysis of Spoken Languageat the Dept. of General Linguistics Christian-Albrechts-Universität zu Kiel
Background• “Reduced” connected speech contains no maskers or
interruptors.• The seemingly deleted information can still be there, but
reorganized in a suprasegmental, non-linear representation. Perceptual conditions differ completely from the original line
of research on phonemic restoration.
• (Q1): Do we find auditory restoration under these conditions, when there is actually nothing to “undelete”?
• (Q2): If there is restoration, is the “phoneme” (which is in the first line a heuristic, meta-linguistic concept) an adequate operational unit? Wouldn’t a suprasegmental unit like the “syllable” be more suitable?
• As regards (Q2), there is experimental evidence in favour of phoneme restoration. However, the corresponding studies used phoneme-oriented tasks like “phoneme-monitoring” and orthography-related judgments. The presented study will use a more neutral task.
21.05.2011 Oliver Niebuhr 8
Analysis of Spoken Languageat the Dept. of General Linguistics Christian-Albrechts-Universität zu Kiel
Stimulus material – The SYLLABLE series
(German discount chain)
(frog puppet, Muppet Show)
(knowledge)
All 2-syllable nouns, 650 ms long
+(to see/to watch)
2-syllable verb, 700 ms long
7 syll. = +36 syll. = +25 syll. = +1
(2+2 syll., equal overall duration 1.350 ms)
ISO
con
dit
ion
WO
RD
+ co
nd
ition
„Nun wollen wir mal gucken“ (Now, let us see)„Können wir mit gucken“ (May we watch with you)
„Willst Du den gucken“ (Do you want to watch it)
21.05.2011 Oliver Niebuhr 9
Analysis of Spoken Languageat the Dept. of General Linguistics Christian-Albrechts-Universität zu Kiel
Stimulus material – The PHONEME seriesAll 2-syllable nouns, 620 ms long 2-syllable noun, 680 ms long
5 syll.= +1,+ 5 phonms.5 syll.= +1,+ 3 phonms.5 syll.= +1,+ 2 phonms.
(2+2 syll., equal overall duration 1.300 ms)
(German hanseatic city)
(hammer)
(take it)
+(soft drink)
ISO
con
dit
ion
WO
RD
+ co
nd
ition
„Willst Du mal Cola“ (Do you want Cola)„Haben wir Cola“ (Do we have Cola)
„Nehmen Sie Cola“ (Do you take Cola)
21.05.2011 Oliver Niebuhr 10
Analysis of Spoken Languageat the Dept. of General Linguistics Christian-Albrechts-Universität zu Kiel
Experiment/Task• Pairwise comparisons with regard to stimulus duration
between• the target stimuli (A)…• …and []-like reference stimuli (X)
• Rationale: if there are more or less comprehensive restorations in the target stimuli, they will appear longer than the []-like reference stimuli • (–) indirect judgments, which can only provide indirect evidence.• (+) listeners’ attention is not explicitly drawn to phonemic units, but to the utterance as a whole; both stimuli are speech or speech-like
• The []-like reference stimuli were phonetically constant, but varied in duration from -150 ms to +600 ms relative to the duration of the respective target stimulus (620; 650; 1.300; 1.350 ms)
• Stimulus pairings were presented (with several randomized repetitions) in both AX and XA orders
21.05.2011 Oliver Niebuhr 11
Analysis of Spoken Languageat the Dept. of General Linguistics Christian-Albrechts-Universität zu Kiel
Experiment/Task• Two separate experimental sessions with two groups of naïve
subjects
ISO stimuli : SYLLABLE
+
WORD+ stimuli : SYLLABLE
+
WORD+ stimuli : PHONEME
ISO stimuli : PHONEME
Judged by subject group #1in AX/XA pairs
Judged by subject group #2in AX/XA pairs
21.05.2011 Oliver Niebuhr 12
Analysis of Spoken Languageat the Dept. of General Linguistics Christian-Albrechts-Universität zu Kiel
Results 1: Perceived wordings• The target stimuli were presented (together with a list of filler
items in an overall randomized order) to a third group of 12 Northern Standard German listeners.
• Their task: “Write down what you hear”.
• Result: The intended wordings were unequivocally identified in the target stimuli.
• It can be assumed that the same perceived wordings underlay the duration judgments of the other two groups of listeners.
• On this basis, the main results show the following…
21.05.2011 Oliver Niebuhr 13
Analysis of Spoken Languageat the Dept. of General Linguistics Christian-Albrechts-Universität zu Kiel
• Even ISO stimuli appeared slightly longer (on average 37 ms) than the [] references with physically identical durations.
• The WORD+ stimuli, for which auditory restoration can occur, appear longer than theISO stimuli.
• The more syllablescan be restored,the longer is thestimulus perceived
relative to []
Results 2a: SYLLABLE stimuli
+0 syll. +1 syll. +2 syll. +3 syll.
21.05.2011 Oliver Niebuhr 14
Analysis of Spoken Languageat the Dept. of General Linguistics Christian-Albrechts-Universität zu Kiel
• Average reaction times in the duration-oriented AX/XA comparisons increase, the more syllables can in principle be restored in the target stimuli.
Results 2b: SYLLABLE stimuli
+1 syll.
+2 sy
ll.
+3 syll.
+0 syll. +0 syll. +0 syll.
21.05.2011 Oliver Niebuhr 15
Analysis of Spoken Languageat the Dept. of General Linguistics Christian-Albrechts-Universität zu Kiel
• Even ISO stimuli appeared slightly longer (on average 66 ms) than the [] references with physically identical durations.
• The WORD+ stimuli, for which auditory restoration can occur in terms of +1 syll. and +2 to +5 phonemes, appear longer than theISO stimuli.
• The WORD+ stimuli,in which no syllables,but only phonemescan be restored, donot differ from eachother.
Results 3a: PHONEME stimuli
+0 syll. +2 phnms +3 phnms +5 phnms
21.05.2011 Oliver Niebuhr 16
Analysis of Spoken Languageat the Dept. of General Linguistics Christian-Albrechts-Universität zu Kiel
• Average reaction times increase for the PHONEME stimuli between ISO and WORD+, i.e. when there is a syllable to restore, but the reaction times remain constant withinthe WORD+ stimuli, for which auditory restoration can occur only in terms of +2 to +5 phonemes.
Results 3b: PHONEME stimuli
+0 syll. +0 syll. +0 syll.
+1 syll. +1 syll. +1 syll.+2 phnms +3phnms +5 phnms
21.05.2011 Oliver Niebuhr 17
Analysis of Spoken Languageat the Dept. of General Linguistics Christian-Albrechts-Universität zu Kiel
• The present study provided clear, but indirect evidence that auditory restoration occurs not just for masked speech, but also for “reduced” connected speech.
Previous evidence in favour of auditory restoration was not an artefact of a phoneme or orthography-oriented task.
• However, the operational unit of the restoration seems to be a suprasegmental one, which is larger than the phoneme (i.e. a single speech sound). It need not be what we refer to as ‘syllable’.
• Besides the empirical support for auditory restoration, it seems that we do not really know yet, when it occurs and what is actually restored…• canonical/full forms in all details?• basic sound and pitch qualities?• just a temporal/rhythmical grid?
Discussion
This must become a separate line of research in future
studies on speech perception