Chapter 9 Source-Filter Theory and Problems in Speech Production

Clinical Applications of
Articulation Therapy
Chapter 4
Perry C. Hanavan, Au.D.
• Ken Stevens x-ray film
Strain Gage
• The Iowa Oral Performance Instrument
(IOPI) is used to objectively measure
tongue and lip strength and endurance
– Also provides biofeedback for oral motor
X-ray Microbeam
• Microbeam analyzes speech
patterns by tracking small pellets
placed on the subject’s tongue, teeth
and nose
• Tracking accomplished by a very
narrow x-ray beam passing through
the subject area and detected by a
sodium iodide crystal located behind
the head
• Dense pellets block the x-rays from
reaching the crystal
• Allows study of speech patterns in
real time
• Speech therapists are
using ultrasound
• SmartPalate
Oral Devices
• Electropalatography
• Glossometry
• Video with Dr. Samuel Fletcher
• Device that consists
of electrodes
mounted on a thin
acrylic plate which is
custom made to cover
the individual’s hard
palate and upper
teeth and measures
tongue and palate
contact patterns
from electrodes.
• Device that consists
of electrodes
mounted on a thin
acrylic plate which is
custom made to cover
the individual’s hard
palate and upper
teeth and measures
optical tracking of
tongue surface
using LED.
• Primarily suitable for static
• Attempted to acquire dynamic MRI
image sequences, i.e. MRI
• One technique involves acquisition
of single images from an utterance
repeated over and over
• A new technique for magnetic
resonance imaging (MRI) allows
movements of joints and organs to
be captured in real time
Electromagnetic Articulography
• See inside patients’ mouths to track
their speech movements.
• Only about 40 in the world,
• Holds out promise as a therapy tool
for people who have lost ability to
• Small sensors attached to thin wires
placed inside mouth with magnified
images of mouth movements
appearing on screen
• helps patients by showing how to
position tongue to create speech
Source Filter Theory and
Problems in Speech Production
• Source-filter a way of conceptualizing
problems of speech production
– Dysarthria—neurologic disorder with weak speech
– Hearing loss—difficulty with relationship with
acoustic input and speech production
– Phonological disorders—often phoneme perceptual
– Tracheotomy—larynx development, tongue
– Cleft Palate—velopharyngeal problems
(resonance—nasality problems)
• Neurological disorders with weak speech
– "Slurred" speech
– Speaking softly or barely able to whisper
– Slow rate of speech
– Rapid speech rate with a "mumbling" quality
– Limited tongue, lip, and jaw movement
– Abnormal intonation (rhythm) when speaking
– Hoarseness, breathiness
– Drooling or poor control of saliva
– Chewing and swallowing difficulty
Vowel Space
Slope index
• This parameter is
measured in Hz per
msec, is based on
the relationship
between the F2
transitions and
place of articulation
“Deaf Speech”
• Individuals with congenital or pre-lingual
hearing loss vs. post-lingual loss
• Loss of speech intelligibility
• Difficulty in segmental aspects of speech
• Difficulty in control of suprasegmental
aspects of speech
• Difficulty co-articulating
Segmental Problems
• Most frequent errors in spoken language of deaf
– Vowel problems (tend to neutralize vowels)
– F1/F2/ charts shows marked limitations in both
horizontal and vertical degree of tongue movements
for vowels
– Consonant errors common—omissions and
substitutions involving voicing and manner of artic
– Place of production errors common because of
imprecise tongue position and reduced articulatory
Acoustic Analysis of Speech
• Alveolar and velar stops produced further
back in the vocal tract than normal
– Provides clues for speech therapy
Suprasegmental Aspects
• Incorrect Fo in word and sentence
• Not enough variation in Fo to differentiate
between declarative vs. interrogative
Speech Therapy Emphasis
• Some programs put emphasis on speech
in education process, others some, and
yet others put none
• Maasen & Povel (1985) research showed
improving segmental production caused
50% improvement in intelligibility with
major increase resulting from correcting
vowel production
Phonological Disorders
• Speech disorder known as an articulation
• Do not use some or all of the speech
sounds expected for their age group.
• Phonological processes
– Children use alternative articulation or simpler
articulatory gestures in place of the adult
– May produce a /t/ for /k/ sound
– Sample
• Surgical procedure to create an opening through
the neck into the trachea
• Developmental consequences in infants
– Prevention of larynx from making developmental
– Thus limiting movement of tongue
– Reduction in articulatory movements
– Alteration of resonance characteristics
– Sample
– Sample
Cleft Palate
• Congenital split in the roof of the mouth.
• Resonance issues
• High incidence of conductive hearing loss
(typically middle ear infections)
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