Download Differential Interaural Intensity Difference (DIID) Procedure

Differential Interaural
Intensity Difference (DIID)
Procedure
Jane A. Baran, Ph.D.
Department of Communication Disorders
University of Massachusetts Amherst
Background
ƒ It has also been observed that many children
and adults with auditory processing disorders
demonstrate similar types of auditory deficits as
do patients who have undergone surgical
sectioning of the corpus callosum (Musiek et al.,
1984, Musiek et al.,1994).
ƒ Therefore, a training procedure was developed
that could be used with children (and adults) in
an effort to remediate ear deficits noted on
dichotic speech tests
Background
ƒ Application of procedure is
based upon the physiological
mechanisms underlying
dichotic speech processing
ƒ Within the CANS, there are
two main pathways that bring
auditory information from the
periphery to the auditory
regions of the cortex
• contralateral pathways
• ipsilateral pathways
Background
ƒ Procedure developed to address central auditory
deficits in dichotic processing of speech signals
ƒ Its development was based upon earlier
observations that some patients who had
undergone commissurotomies (complete or
posterior) demonstrated improved left ear scores
on dichotic speech tests when the intensity of
the stimuli presented to the right ear was
reduced (Musiek et al., 1979).
Background
ƒ Procedure takes advantage of improved dichotic
performance when speech stimuli are presented to the
two ears in a more favorable listening condition (i.e., by
reducing the intensity of the stimuli presented to the
better ear until performance in the “deficit” ear reaches
normal/near normal levels)
ƒ The intensity of the signal to the better ear is then
increased using an adaptive procedure—thus reducing
the interaural intensity difference (IID) between the two
ears until the presentation levels of the stimuli presented
to both ears are equal
ƒ Presumably leads to alterations in neural
function—brain plasticity
Background
ƒ Under normal listening conditions either pathway
can convey the neural information from the
periphery to the auditory cortex for processing*
ƒ Under dichotic listening conditions, the ipsilateral
pathways are believed to be suppressed and
information travels to the auditory cortex via the
contralateral pathways*
• Right ear to left hemisphere
• Left ear to right hemisphere
¾ If the stimulus presented to the left ear is speech, then neural
information must travel from right hemisphere to left hemisphere via the
interhemispheric pathways for language processing
*Model proposed by Kimura (1961)
1
Intervention Protocol
Determining Candidacy
ƒ Document that a dichotic processing deficit is present
ƒ Determine candidacy
ƒ Implement training program
ƒ Complete post-training
assessment(s)
ƒ Establish a crossover performance point by reducing the
intensity of the stimuli presented to the better ear
ƒ Verify that the following two conditions are met at the
crossover point
• Performance in the poorer ear is at normal or near normal limits
at the crossover level
• Intensity of the stimulus presented to the better ear does not
drop below the level of audibility
If these two conditions are not met, then the individual is not a good
candidate for the DIID procedure
Example of the Procedure Used to
Establish the Crossover Point
ƒ Once crossover point and candidacy for procedure are established,
training can begin
ƒ Initial training begins with an IID that is 3 to 5 dB greater than that of
the crossover point
Right Ear
Left Ear
96% @ 50 dB
88% @ 40 dB
70% @ 30 dB
50% @ 25 dB
38% @ 20 dB
42% @ 50 dB
50% @ 40 dB
58% @ 30 dB
76% @ 25 dB
86% @ 20 dB
Example of Dichotic Training
Arrangement
Dichotic digit scores = 96% RE, 42% LE
20 dB HL
Intervention Protocol
50 dB HL
ƒ A variety of dichotic tasks are administered at this IID (as well as
subsequent IIDs). These should include:
• different types of dichotic stimuli (e.g., dichotic words, digits, CVs, and
sentences)
• tasks that require the patient to attend to both ears, as well as tasks that
require the individual to direct attention to only one ear at a time
• Patient is asked to repeat all stimuli heard in one or both ears depending on
procedure being used
• Other tasks can also be included (e.g., identification of the location [right ear
or left ear] of target words in sentences).
Intervention Protocol
ƒ Patients should be seen for DIID training for 15 to 30
minute sessions for a total of 3 to 4 sessions per week
ƒ After a week of training at the initial IID level, the IID
should be reduced (i.e., the intensity of the stimuli
presented to the “better ear” should be increased while
the presentation level of the stimuli to the “poorer ear” is
maintained at 50 dB HL
• For most patients, this will mean increasing the intensity of the
stimuli presented to the right ear (better ear) without adjusting
the level of the stimuli presented to the left ear (poorer ear)
2
Intervention Protocol
Example: Adaptive Approach
100 %
Performance
LE
ƒ If performance in the poorer ear is 80% or better
following the decrease in IID, then training should
continue at this IID for the remainder of the week
(50 dB HL maintained)
ƒ If performance drops below 80%, the IID should be
increased in 1 dB increments until performance of the
poorer ear on the dichotic task(s) reaches 80% or until
the IID level returns to the starting level – training should
continue at this level for the remainder of the week
RE
ƒ During each subsequent week of training, the initial
training session should begin with an attempt to
decrease the IID
20 dB
• this procedure should be followed until such time as the patient
begins to show rapid improvements in performance
50 dB
0%
Training Sessions
(courtesy of Frank Musiek)
Intervention Protocol
Considerations
ƒ If and when the patient begins to show rapid and
significant increases in performance,
decrements in the IID can be made at the
beginning of each session
ƒ It may take several sessions for a patient to
tolerate any change in the initial IID
ƒ Improvements are often noted in incremental
steps and not an a gradual continuum of
improvement
ƒ Ultimate goal is to have patient perform dichotic
processing tasks within the normal limits of
performance for both ears when the dichotic
stimuli are presented at equal sensation levels
ƒ If goals are not achieved within 3 months, then it
is unlikely that the patient will receive additional
benefits from training
ƒ For more information on this procedure, see
Weihing and Musiek, in press.
Case Study #1*
100
ƒ An 11-year-old with auditory, reading, and spelling
difficulties
• moderate to severe left ear deficits on dichotic speech tests
(competing sentences and dichotic digits)
• a severe bilateral deficit on a monaural low redundancy speech
test (low-pass filtered speech)
• a severe deficit on a temporal patterning test (frequency pattern
sequences)*
Digits
O
O
LPFS F. Patt C. ED.
5
75
X
X
50
25
X
Case Study #1
Pre- and postintervention test
results for an 11 y.o.
with auditory, reading,
& spelling difficulties.
Training was on
dichotics.
X
% Correct
ƒ Child presented with the following deficits:
C. Sent
X O
O
X
Key:
ƒ Training was completed with dichotic speech materials
0
* Testing was done in the sound field
(*courtesy of Frank Musiek)
0
(courtesy of Frank Musiek)
3
Case Study #2*
Case #2: History
ƒ 58-year-old male who suffered a CVA
ƒ No hearing problems noted pre-CVA
ƒ CT scan revealed a large subcortical bleed in
the temporoparietal area
ƒ Post-CVA, the patient experienced a number of
auditory problems
ƒ left vertebral angiography revealed an occlusion
of the left posterior parietal and angular
branches of the middle cerebral artery
ƒ diagnosis was a arteriovenous malformation
(*courtesy of Weihing & Musiek)
Case #2: History
• difficulty following rapid speech
• problems conversing in group settings
• difficulty hearing on the phone with the right ear
• severe difficulty hearing in presence of background
noise
Case #2: Audiogram
ƒ Following the CVA, the patient initially presented with
global aphasia
ƒ At 14 months post-CVA, he had improved considerably,
but still demonstrated the following speech and language
disorders
• mild to moderate anomia for nouns and verbs
• mild to moderate comprehension difficulties, with the severity of
the difficulties consistent with the complexity of materials
• mild apraxia for speech
(From Weihing & Musiek, in press)
Case #2: Initial Central Test Results
Case #2: Performance on a dichotic speech task over
the course of DIID training
1
2
3
4
5
6
LE RE LE RE LE RE LE RE LE RE LE RE
100
X O X O
X
Key:
1 Dichotic Rhyme
2 Double dichotic Digits
75
3 Single Dichotic Digits
X
50
O
O
O
X
25
4 Duration Patterns
X
5 Frequency Patterns
6 Auditory Closure
(Adapted from Weihing & Musiek, in press)
O
(From Weihing & Musiek, in press)
0
Normal Range
X, O = LE, RE
4
Case #2: Percent change in central test performance
noted for pre- and post-intervention comparisons
Improvement for three patients with LE
deficits on dichotic tests after training
30
Key:
20
15
10
5
0
3
2
6
1
4
•
Dichotic Rhymes
•
Double Dichotic Digits
•
Single Dichotic Digits
•
Duration Patterns
•
Frequency Patterns
•
Auditory Closure
5
Percent Improvement
Percent Change (Post – Pre)
40
RIGHT EAR
25
32-62%
30
20
72-88%
76-88%
10
-5
-10
0
(Adapted from Weihing & Musiek, in press)
Efficacy Studies
Left ear
Mean performance change on
two dichotic tests (dichotic digits
and competing sentences)
following training on dichotic
materials as reported in two
preliminary studies.
Right ear
Mean Percent Change
20
15
A. Musiek, unpublished
data (training involved
two to three 20-min.
sessions per week for
approximately three
months)
10
5
0
Digits-A
C.Sent.-A
(Adapted from Musiek et al., 2007)
Digits-B
B. Wertz & Montcrieff,
unpublished data
(training involved three
30-min sessions per
week for four weeks)
Conclusions
Conclusions
ƒ Preliminary data suggest that the DIID
• is an efficacious intervention procedure for
dichotic processing deficits
• can potentially be used with a wide range of
patients with dichotic processing deficits,
including
• children and adults
• individuals with comorbid peripheral hearing losses
(e.g., those with mild to moderate hearing losses)
• some individuals with comorbid speech and
language problems
Acknowledgments
ƒ Further research is needed to:
• establish the efficacy of the procedure
• determine the type, frequency, and extent of
training necessary to achieve the desired
treatment outcomes
• identify the underlying neurophysiological
changes that accompany the behavioral
changes (improvements) noted over the
course of training
•
•
•
•
•
Frank Musiek
Jeffery Weihing
Deborah Montcrieff
Diane Wertz
Eliane Schochat
5
References
References
Baran, J.A., Shinn, J.B., & Musiek, F.E. (2006). New developments in the
assessment and management of auditory processing disorders.
Audiological Medicine, 4, 35-45.
Musiek, F.E., Gollegly, K.M. & Baran, J.A. (1984). Myelination of the corpus
callosum in learning disabled children: Theoretical and clinical implications.
Seminars in Hearing, 5, 231-241.
Kimura, D. (1961). Some effects of temporal lobe damage on auditory
perception. Canadian Journal of Psychology, 15, 156-165.
Musiek, F.E., & Schochat, E. (1998). Auditory training and central auditory
processing disorders: A case study. Seminars in Hearing, 19, 357-366.
Musiek, F.E., Baran, J.A., & Pinheiro, M.L. (1994). Neuroaudiology: Case
Studies. San Diego: Singular Publishing Group.
Musiek, F.E., Wilson, D., & Pinheiro, M.L. (1979). Audiological manifestations
in “split brain” patients. Journal of the American Auditory Society, 5, 25-29.
Musiek, F.E., Chermak, G.D., & Weihing, J. (2007). Auditory Training. In G.D.
Chemak & F.E. Musiek (eds). Handbook of (Central) Auditory Processing
Disorder: Comprehensive Intervention (pp. 77-106). San Diego: Plural
Publishing, Inc.
Weihing, J.A., & Musiek, F.E. (in press). Dichotic interaural intensity
difference training: Principles and procedures. To appear in D. Geffner &
Deborah Ross-Swain (eds.), Handbook for Auditory Processing Disorders:
Assessment, Management and Treatment. San Diego: Plural Publishing,
Inc.
6