Dr. Hughes - Independent Medical Opinion

Enclosed herewith are my responses, listed in corresponding order to the numbered queries, to your request for additional information as outlined in your recent letter of December 19, 2003.

Although there is no documented set of standards for assessing response reliability, we as audiologists are instructed to use as many procedures as possible, in that the more tests utilized the more accurate the reliability judgement, rather than relying on just one test alone.

Basic customary procedures for a full diagnostic assessment of any individual, veteran or non-veteran, involve both air and bone conduction thresholds, speech reception thresholds, word recognition scores, and impedance audiometry including both tympanograms and acoustic reflexes. All of these combined are used to establish agreement or disagreement among the various procedures, and so determine the level of reliability.

2) Diagnostic evaluations are comprehensive assessments utilizing as many test procedures as possible to determine, not only the presence of hearing loss, but also its nature. In addition, they also assist in determination of habilitation/rehabilitation needs and/or need for medical intervention. On the other hand, screening is simply a tool to indicate the presence or absence of a hearing impairment.

Since results of the 1975 assessment show only air conduction thresholds, I would conclude that this was used as a screening tool.

With regard to reliability, this would depend on the audiologist's/examiner's experience in interpretation of the patient's manner of response. Personally, I would judge that this screening exhibits some reliability in that there is a hearing impairment evident bilaterally and that the hearing deficit is similar in both ears.

The only way it could be used for comparison purposes with the other two audiograms is that it shows there is a deficit in the high-frequency ranges.

3) In the 1975 audiogram, only air conduction thresholds were evident. This informs us that there is indeed hearing impairment (re right ear at 3000 through 8000Hz/ left ear at 2000, 4000, 6000 and 8000Hz). However, it does not reveal the nature of the loss (i.e. conductive, mixed, sensorineural); bone conduction assessment would determine this.

Speech reception thresholds and word recognition also assist in confirming the nature and estimated degree of impairment, as well as reliability. Although persons with conductive losses may need elevated presentation levels for speech audiometry, they generally achieve scores of 96% to 100%. Whereas, those presenting with mixed and/or sensorineural losses may show reduced word recognition, dependent on the degree and frequency involvement of the loss; higher frequency losses reflect poorer scores.

Impedance audiometry, generally, comprises tympanometry and acoustic reflexes. Tympanograms are graphs reflecting compliance, impedance of the middle ear, and thereby assess the nature of a hearing impairment as to whether or not there is any conductive component involved. Acoustic immittance aids in diagnosing of peripheral and central hearing disorders, and to some degree, the levels of the hearing impairment.

4) Whenever an audiometric assessment is to be performed, the ambient noise of the environment should be reduced or eliminated. In a clinical setting, audiologists usually use a sound-treated booth.

If background noise is present during testing, it can elevate thresholds (make the hearing loss more pronounced) especially in the lower frequency ranges such as 250 and 500 Hz; noise masks test signals.

However, judging by the threshold levels, especially at 250 Hz, I would conclude that ambient noise during the 1975 evaluation was fairly quiet.

5) Clinical audiometers usually measure in 5dB increments, but research and/or digital audiometers can register 1dB steps. In my opinion, this is simply a format issue and has no significant impact on the outcome of the testing. It would not significantly influence my reading of an audiogram.

In summary, let me assure you that although materials were received from two sources, I performed an independent evaluation stating only facts that I could substantiate as an audiologist, or that could be re-confirmed by any other Canadian-trained audiologist.

Although I quoted Veterans Affairs guidelines in my initial submission, they were used simply as a preamble to my opinions. There is nothing in those guidelines differing from customary procedures followed by audiologists in assessing any individual, veteran or non­veteran, across Canada.

Although I received, from N. Hobson "opinions and evidence" from other audiologists, their interpretations had no reflection whatever on my evaluation of the audiometric data. In fact, I transcribed the data from each assessment onto my own audiometric sheets so as not to be influenced by each different format, but only by the recorded information.

As an audiologist, I would accept the 1975 assessment as a reliable screening tool, to identify the presence of a hearing impairment only (re right ear at 3000 through 8000Hz and left ear at 2000, 4000, 6000 and 8oooHz).

Hearing impairment is a matter of degree and pattern. The etiology of sensori-neural impairments cannot be determined from the audiogram alone, although certain causes do produce somewhat typical audiometric pictures. Noise-induced hearing loss - exposure to extreme noise for long periods to produce permanent hearing loss - usually is reflected in the audiogram by occurrence of the greatest amount of loss around 4000 Hz, with perhaps some recovery at higher frequencies (Audiology 5th Edition - Hayes A. Newby, Gerald R. Popelka). Based on this I would hazard a guess that the 1975 evaluation suggests a possible noise-induced loss. However, persons whose screenings reflect hearing deficits should be referred for a complete diagnostic assessment to determine, for certain, the exact nature of the loss and the rehabilitative needs.

Whether the degree of loss reflected in the 1975 evaluation "constitutes a disability for pension entitlement" is not within my jurisdiction, as an audiologist, to decide.

Hopefully, this additional information will clarify any discrepancies.

Other than this current appeal, I have not performed any formal written evaluations for Veterans Affairs Canada. However, in the past, I was contacted a number of times by Dr. Winona Foster regarding hearing aids and pricing policies of western Canada versus the lower rates of eastern Canada.