Acoustic compensation and articulo motor reorganisation in perturbed speech [Elektronische Ressource] / von Jana Brunner

Brunner, M.A. Jana

Informations

• Publié par: humboldt-universitat_zu_berlin
• Publié le: 01 janvier 2008
• Nombre de lectures: 5
• Langue: English
• Poids de l'ouvrage: 1 Mo

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Acoustic compensation and articulo-motor
reorganisation in perturbed speech
DISSERTATION
zur Erlangung des akademischen Grades
doctor philosophiae
(Dr. phil.)
im Fach Allgemeine Sprachwissenschaft
eingereicht an der
Philosophische Fakultät II
Humboldt-Universität zu Berlin
und dem
Institut Nationale Polytechnique de Grenoble
von
Jana Brunner, M.A.
geboren am 17.07.1978 in Eisenach
Präsident der Humboldt-Universität zu Berlin :
Prof. Dr. Christoph Markschies
Dekan der Philosophische Fakultät II :
Prof. Dr. Michael Kämper-van den Boogaart
Gutachter :
1. Prof. Dr. Bernd Pompino-Marschall
2. Dr. Janet Fletcher
3. Prof. Dr. Rudolph Sock
eingereicht am : 5. Februar 2008
Tag der mündlichen Prüfung : 30. Mai 2008iiAbstract
The present study describes the results of a 2 week perturbation experi-
ment where speakers’ vocal tract shape was modified due to the presence of
an artificial palate. The aim of the work is to investigate whether speak-
ers adapt towards acoustic or articulatory targets. Speakers were recorded
regularly over the adaptation time via electromagnetic articulography and
acoustics. Immediately after perturbation onset speakers’ auditory feedback
was masked with white noise in order to investigate speakers’ compensatory
behaviour when auditory feedback was absent.
The results of acoustic measurements show that in vowel production
speakers compensate very soon. The compensation in fricatives takes longer
and is in some cases not completed within the two weeks. Within a session
and for each speaker the sounds can be distinguished solely by acoustic pa-
rameters. The difference between the session when no auditory feedback was
available and the session when auditory feedback was available was greater
for vowels with less palatal contact than for vowels with much palatal con-
tact. In consonant production auditory feedback is primarily used in order
to adapt sibilant productions. In general, adaptation tries to keep or enlarge
the articulatory and acoustic space between the sounds. Over sessions speak-
ers show motor equivalent strategies (lip protrusion vs. tongue back raising)
in the production of /u/. Measurements of tangential jerk suggest that after
perturbation onset there is an increase in articulatory effort which is followed
by a decrease towards the end of the adaptation time.
Thecompensatoryabilitiesofspeakerswhennoauditoryfeedbackisavail-
able suggest that speakers dispose of an articulatory representation. The fact
that motor equivalent strategies are used by the speakers, however, supports
acoustic representations of speech. It is therefore concluded that articula-
tory representations belong to the speech production tasks. However, since
they are modified as soon as the acoustic output is not the desired one any
more, they rather function in the domain of movement organisation and the
acoustic representations dominate.
Keywords:
articulation, perturbation, compensation, movement optimisation, phoneme
representationsZusammenfassung
Die Studie befasst sich mit der Adaption der Artikulation als Folge einer
insgesamt zweiwöchigen Veränderung der Vokaltraktgeometrie durch einen
künstlichen Gaumen. Ziel der Arbeit ist zu untersuchen, ob die Adaption
auf artikulatorische oder akustische Ziele hin erfolgt. Die Produktionen der
Sprecher wurden während der Adaptionszeit regelmäßig akustisch und per
elektromagnetischer Artikulographie aufgenommen.
Akustische Analysen haben gezeigt, dass die Vokalproduktion sofort nach
Perturbationsbeginn adaptiert wird. Für die Adaption der Frikative benöti-
gen die Sprecher mehr Zeit, in einigen Fällen ist die zweiwöchige Adapti-
onszeit nicht ausreichend. Wenn die Daten nach Sprecher und Aufnahme
getrennt betrachtet werden, nehmen die Produktionen einzelner Phoneme
abgrenzbare Regionen im akustischen Raum ein. Der Einfluss der auditiven
Rückmeldung ist stärker bei Vokalen mit weniger linguo-palatalem Kontakt
als bei Vokalen mit viel Kontakt. Bei den Frikativen scheint die auditive
Rückmeldung vor allem für die Sibilantenproduktion von Bedeutung zu sein.
Generall hat die Adaption zum Ziel, die Abstände zwischen den Lauten bei-
zubehalten oder zu vergrößern. Untersuchungen zur Artikulation des /u/
zeigen, dass die Sprecher über die Sitzungen hinweg motorisch äquivalente
Strategien benutzen (Lippenvorstülpung versus Hebung des Zungenrückens).
Messungen des Rucks (engl. jerk) für artikulatorische Gesten deuten darauf
hin, dass der artikulatorische Aufwand nach Perturbationsbeginn steigt und
zum Ende der Perturbation hin wieder fällt.
Die Fähigkeit der Sprecher zu kompensieren wenn keine auditive Rück-
meldung vorhanden ist, zeigt, dass Sprecher über artikulatorische Repräsen-
tationen verfügen. Die Tatsache, dass motorisch äquivalente Strategien von
den Sprechern genutzt werden, unterstützt jedoch akustische Repräsentatio-
nen der Phoneme. Die Schlussfolgerung, die aus der Untersuchung gezogen
wird, ist daher, dass artikulatorische Repräsentationen beim Sprecher exis-
tieren, dass sie aber vor allem der Bewegungsorganisation dienen. Sobald das
akustische Resultat nicht mehr das gewünschte ist, beginnen die Sprecher,
die Artikulation zu verändern.
Schlagwörter:
Artikulation, Perturbation, Kompensation, Bewegungsoptimierung,
PhonemrepräsentationenPreface: Aim and structure of
the study
This study presents the results of a speech perturbation experiment where
the vocal tract shape of seven speakers was modified by a palatal prosthesis
andspeakersadaptedtheirarticulationtothismorphologicalchangewiththe
aim to produce speech which sounds normal to them. The adaptation time
was two weeks. Speakers wore the palatal prosthesis all day long and prac-
ticed speaking. Their articulation was recorded via 2D (five speakers) or 3D
(two speakers) electromagnetic articulography. In the initial perturbed ses-
sion speakers’ auditory feedback was masked in order to investigate speakers’
compensatory abilities when only tactile feedback was available. The data
were analysed in an effort to find out whether speakers adapt towards ar-
ticulatory or towards acoustic targets. The results of this study therefore
contribute to the knowledge of productional targets, but possibly also to the
one of perceptual targets. They furthermore provide new insights in speech
motor control and movement organisation.
TheworkwascarriedoutintheframeworkoftheDFG-project Akustische
Kompensation und artikulo-motorische Reorganisation bei künstlich verän-
derten Gaumenformen. This project is a co-operation between the Institut
für Phonetik und Sprachverarbeitung of the Ludwig-Maximilians-Universität
Munich and the Institut für deutsche Sprache und Linguistik of the Hum-
boldt-Universität zu Berlin. Part of the data discussed here were provided by
the Munich partner (two speakers), the rest of the data was recorded at the
Zentrum für Allgemeine Sprachwissenschaft in Berlin. The primary analysis
steps (acoustic segmentation, formant measurements and articulatory seg-
mentation) were carried out to equal parts in Berlin and Munich.
The study deals with articulatory data and discusses the nature of phone-
mic targets in speech production. The final aim of this work is thus to shed
light on the question whether the aim of a speaker is to produce a certain
acoustic output or a certain articulatory movement. More concretely, the
question is: What is the goal of an adaptation process and what is only an
vauxiliary means? Do speakers aim at producing a certain acoustic output
and the articulatory movements are the auxiliary means or do speakers aim
at producing articulatory movements and the acoustic output is only the
consequence of it?
While an answer to this question gives insights into speech production
mechanisms it might add knowledge to the perceptual area as well, i.e. to
the question whether what is perceived by a listener are the articulatory
movementsorwhetherthelinguisticmessageisdirectlyintheacousticsignal.
More concretely, the perceptual question to which this work might contribute
iswhetherlistenerswhohearasounddirectlyperceivethearticulatoryaction
or event which is transmitted by the acoustic signal or whether they take
the linguistic message directly from the signal and the articulatory
movements are just a means to produce them. Thus, it is again the question
of what is primary and what is an auxiliary means: If one assumes that a
listener perceives articulatory movements, these articulatory movements are
primary and the acoustic signal is the auxiliary means, it just transmits the
signal. If one assumes that the listener takes the message from the acoustic
signal, this acoustic signal is primary and the articulatory movements are
just the auxiliary means: They are used in order to produce the acoustic
signal.
While these questions at first sight seem to be rather theoretical, they
bear important implications for a number of other research questions in the
field of phonetics and linguistics. To give an example, explanations of lan-
guage change always pr