Highlighted historical overview of research and
study projects performed at Aural Rehab Concepts and
DigiCare Hearing Research & Rehabilitation
1981-2002.REVIEW OF RESEARCH AND STUDY PROJECTS:
1981-2002
Since 1981, many important research and study
projects have been conducted under the auspices of
Aural Rehab Concepts and, later, DigiCare Hearing
Research & Rehabilitation. These and others too
numerous to list here have contributed significantly
to the fields of hearing health, educational
audiology and special education, and cognitive and
communicative rehabilitation. Following is a
highlighted summary review of some of the more
important projects whose outcomes and
recommendations are in use today:
1981- A NEW PSYCHOLOGICAL MODEL OF HEARING
IMPAIRMENT
Summary description: Development of a psychological
model based on Ramdsdell’s three levels of human
hearing and other concepts, and the psychological
effects of uncorrected hearing loss for children and
adults. Central to the thesis was that when hearing
levels declines in the Primitive (background) Level
of hearing that sound is then perceived in the more
emotionally-influenced Signal (warning) level of
hearing, adding significant stress to an
individual’s life. The object, then, was to correct
hearing levels back into a state that background
sounds could be perceived at the subconscious level,
relieving sufferers of the more stressful, autonomic
effects of hearing loss. Today, Jastreboff’s and
Hazell’s neurophysiological model for hyperacusis
and tinnitus better explains this concept.
1982- TINNITUS & AMPLIFICATION STUDY (TI)
Summary description: Over a 7-year period, 2,000
hearing aid patients who also exhibited tinnitus as
a secondary complaint to hearing loss were studied.
From this study came better correlates between
tinnitus description and site of lesion, as well as
correlation between subjective loudness and
objective measures in decibels above hearing
thresholds. Such phenomena as residual inhibition,
environmental masking, and auditory reattention were
identified as possible benefits of amplification.
1983- DEVELOPMENT OF OBJECTIVE TRANSCRANIAL CROS
FITTING METHOD
Summary description: This project involved
development of assessment and verification protocols
for fitting acoustically unaidable (dead or
profound) ears transcranially in cases where the
other ear is normal or near-normal. Results yielded
a more scientific method for providing the CROS
configuration than conventional approaches, and
utilized tactile pathways from the “dead ear” to
both the good ear and from the tympanic plexus of
the “dead ear” TM to the motor cortex of the
contralateral hemisphere. In doing so, head-shadow
effect was reduced, binaural summation and other
central auditory processing benefits were found, and
an improved signal-to-noise ratio (S/N) were
realized.
1984- THE EFFECTS OF LONG-TERM OVERAMPLIFICATION AND
COMPLIANCE AT THE TYMPANIC MEMBRANE (TM)
Summary description: From a patient base of more
3,000 current hearing aid users, those with a
history of high SSPL90 devices (>127dBSPL) were
selected for tympanometric testing. A strong
correlation was found between prolonged exposure to
amplified sound pressures >127dBSPL and a A-shallow
configuration. This finding added substance to the
FDA mandated warning to prospective users of
amplification at sound pressures of 132dB or above.
1995- “NON-ACOUSTIC OCCLUSION” RESOLUTION PROJECT
Summary description: Research on the role of a
branch of the Vagus Nerve that courses through the
external ear canal and causes complaints of
“occlusion” from hearing aid users. Methodology
developed for setting volume controls, as well as an
acoustic model showing the relationship of the
occlusion complaint to pressure on the Vagus.
1986- TRANSIENT NOISE REDUCTION HEARING AID CIRCUIT
Summary description: In an effort to reduce some of
the artifacts that plagued hearing aid circuits of
era (bothersome internal circuit noise, spurious
peaks that caused feedback and transient distortion,
and amplitude peaks out of sync with speech
formants), new electroacoustic designs and strategic
component integration were developed. As a result of
this project:
-Fidelity bandwidth was expanded from the
traditional 4200Hz to 7200Hz (>9000Hz in high
frequency configuration)
-Three strategic peaks were developed to coincide
with the 2nd, 3rd , & 4th formants of speech (in
English), producing a more audible and broader
response than the single peak, and greater
audibility, which provided the need for less
use-gain.
-A high definition (HD) miniature power circuit for
custom canal instruments
-Extended feedback loop at the output stage for
better “out-of-phase” feedback control and reduced
resonant distortion in open ear (and IROS) models.
1988- THE SPECTRA STATION PROJECT
Summary description: Development of the Spectra
Station acoustic sound enclosure, offering greater
acoustic control of the sound environment for
pure-tone, speech, and soundfield testing. HL
Calibrated soundfield offered for the first time
unaided/aided threshold comparisons, and more
precise Speech-in-Noise (SiN) testing. In 1989, a
new lead-lined Industrial Model (IM) was submitted
for and passed independent testing for compliance
with OSHA regulations.
1989- DEVELOPMENT OF THE FIRST BI-MODAL TINNITUS
INSTRUMENT
Summary description: A combination hearing aid and
tinnitus masker, operated on two separate
use-adjustable volume controls, this instrument
introduced the first movable peak masker with an
adjustable white noise floor, affording the
professional to more accurately target the tinnitus
noise and provide minimal (unobtrusive) broadband
masking in the background. The hearing aid component
portion was of conventional circuit design.
1989- TINNITUS STUDY OF HEARING PROFESSIONALS (TII)
Summary description: Over a two-year period a survey
was conducted at each session of a two-day Tinnitus
Management Seminar among course attendees
(audiologist, dispenser, & physicians) who also
experienced tinnitus. The study was designed to
specify precise frequency band comparisons,
objectively measured intensity above hearing
threshold, and audiogram configuration. The data was
plotted for judging inferential correlates, from
which assessment methodology was developed.
Counseling models were also derived from this study.
1989- ANALYSIS OF U.S. HEALTHCARE REFORM DATA
Summary description: Analyzed data being used in
Congressional hearings for the purpose of
restructuring the U.S. healthcare delivery system.
Cost analysis on hearing care costs re Medicare Part
C, Veteran’s Administration, and Medicaid found that
reform proposals (Pay or Play, etc.) would yield a
hearing aid unit cost (to taxpayers) of 3.4:1 versus
the private delivery system model.
1990- TOTAL HEARING CARE CONCEPT
Summary description: A practice model for dispensing
professionals was developed to assist the patient in
achieving “Communicative Wholeness”. The model
included: appropriate hearing aid fitting,
counseling/training in assistive devices (ALDs),
coping strategies (CS), and referral to other
professionals in the community. Over a 3 year period
this model was taught in an 8-12 format to more than
3,000 hearing health professionals throughout the
U.S. and Canada.
1991- LINGUISTIC ANALYSES ON HEARING AID CIRCUITS
Summary description: In cooperation with hearing aid
design engineers in Italy, linguistic
characteristics of several languages (English,
Spanish, French, German, Portugese, and Italian)
were compared in spectral peak analysis. From there,
hearing aid circuit configurations were designed for
each population to meet specific speech formant
locations.
1993- ANALYSIS OF CLINTON HEALTHCARE REFORM DATA
Summary description: Similar analysis applied to the
1989 data was applied to the Clinton Reform Model,
resulting in argument against that model. In
contrast “trial balloon” programs, such as Medical
Savings Accounts (MSA) and Federal Employees
Insurance Program (FEIP), were found to be far
superior and cost-effective.
1993- JEDMED VIDEO OTOSCOPY PROJECT
Summary description: Involved development of
assessment protocols for use of the video otoscope
in dispensing and audiology practice, as well as
scope of practice review. Reviewed current FDA Red
Flag conditions and their relevance to video
otoscopy.
1993- U.S. Otoscopy & Cerumen Management Survey
Summary description: Each state law was studied and
each state regulatory agency was interviewed
relative to mandatory use of otoscopy in dispensing
practice, as well as possible prohibitions against
cerumen management. From this survey,
interdisciplinary consensus was codified and
published.
1993- ANALYSIS OF FDA HEARING AID RULE AND PROPOSED
CHANGES
Summary description: A line by line review of the
1977 Hearing Aid Rule was administered, as well as a
comparison to proposed changes. Gatekeeper status
seemed to be the only real debate, as almost every
state had already complied with the Rule, and
followed standards of care in licensure law
predicated by the International Hearing Society (IHS).
From this experience came the IHS Uniform Licensing
Model, and considerable overhaul of state licensing
laws all over the U.S., including increased
educational/training requirements for entry-level
dispensing professionals.
1995- DEMOGRAPHIC STUDY OF THE HEARING IMPAIRED
POPULATION (U.S.)
Summary description: Developed statistical template
for a more accurate estimate of demographic data on
the hearing impaired population in the U.S. From
there, statistical data from more than 15 studies,
including data from the U.S. Department of Education
and Department of Health & Human Services, were
calculated to present the most accurate picture of
the current market of all ages and at the four
disability levels (mild, moderate, severe, and
profound). These data were also used to determine
the size of the potential market for multichannel
cochlear implants under the then-current candidacy
criteria.
1997- DEMOGRAPHIC PICTURE OF SEVERELY HEARING
IMPAIRED (SHI) MARKET
Summary description: Codification of recent
research, definitive categorization and inferential
projections of the severe (SHI >70dB PTA) and
profound (SHI >90dB PTA) population. Includes
performance groups (A, B, C) re “best aided” NU-6
hearing only scores. This study helped identify
cochlear implant candidacy under new criteria.
Illustrated in graphs and narrative description.
Template up-dated 1999 and 2001.
1998- EXTERNAL EAR NEURORLEX MODEL
Summary description: Determination of 4
neuroreflexes of the external meatus as they relate
to earmold comfort and adaptation: 1) Vagus reflex
(cough reflex, non-acoustic occlusion, watering
eyes, cardiac tension, nausea), 2) Trigeminal reflex
(“red reflex”, thickening TM at tympanic plexus,
artificially increased SSPL90 output requirements),
Tensor Tympani reflex (taut TM, artificially
increased SSPL90 output requirements), and Lymphatic
reflex (lymphatic swelling at or near point of
pressure due to more than 1 paperweight of pressure,
primarily at the bony isthmus). Remediation,
counseling and earmold modification provided to
improve earmold ergonomics, including ear impression
taking, ear impression modification (before sending
to the lab), and post-fitting modifications re user
experience. Concepts published and taught in “Nuts &
Bolts” and “Problem Fitting Cases” workshops
throughout the U.S. and Canada.
1999- MODEL FOR COMPREHENSIVE AUDITORY
REHABILITATION
Summary description: Extension of previous “Total
Care Dispensing” concept, adding principles of
neuroplasticity of the central auditory process and
auditory cortex. Time-weighted changes monitored in
articulation index (similar to Gatehouse & Killion
H.A.B.R.A.T.), but based upon principles governing
the homunculi.
2000 BOTANICAL SOLUTION EXTERNAL EAR PROJECT
Summary description: Safety and efficacy testing of
botanical solution used for preparation of external
ears for fitting of new hearing instruments.
Developed 2- and 4-week regimen and made video
otoscopy observations to note changes in physiology,
particularly regrowth of missing keratin protein,
which is found to be missing in most new users.
Also, noted changes in non-Red Flag conditions, such
as long-term adhesive otitis residue, calcium-plaque
tympanosclerosis, and healed stress fissures and
past perforations.
2002- HEARING HEALTHCARE & OVER-DIAGNOSES OF
ALZHEIMER’S DIAGNOSIS
Summary description: Codified 36 studies in the
literature on cognitive decline re unmitigated
hearing loss and resultant improved cognitive
function upon auditory rehabilitation. Presented
paper at the American Academy of Audiology in April,
2002 on the need for auditory assessment and
intervention BEFORE medical/clinical diagnosis of
Alzheimer’s disease can be given.
2002- TINNITUS & AMPLIFICATION 2002 STUDY (TA2002)
Summary description: Large population study of
hearing impaired population whose secondary
complaint is tinnitus. Utilizing known benefits of
amplification (residual inhibition, environmental
masking, auditory reattention, stress relief), and
noting long-term changes in patient perception of
tinnitus complaint. Also, documentation of current
medical program, medication dosage(s), dietary and
stress factors that may influence tinnitus
experience. Correlation of data for development of
“Best Practice” models for allied health
professionals. Study ends June, 2003 at which time
data will be collected and published.
Future projects slated for 2003:
1) DIGITAL PROGRAMMING SOFTWARE STRATEGIES FOR
MENIERE’S AND BPPV CASES (CONCURRENT WITH MEDICAL
INTERVENTION)
2) SPATIAL SEPARATION STUDY ON DIGI K (EQUALIZED)
DSP AMPLIFIER
3) Neuroreflexes of the external ear and their role
in hearing aid adaptation
4) Update study on Diabetes Mellitus II, and effects
upon hearing aid candidacy |
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