The Harvard Report Revisited – Kind of….
Sometimes one collects data that could be published, but somehow never gets around to it. This blog involves the results on one such study.*
Background
For many years, the so-called “Harvard Report” has been alternately credited and disparaged. For the uninformed, the general finding of the Report was that the desired response for the majority of patients with hearing impairment were hearing aids with a frequency response that was slightly rising with frequency (a range of slope between 0 and +6 dB/octave), along with various other recommended parameters {{1}}[[1]] Davis, H., Stevens, S.S., Nichols, R.H., Jr., Hudgins, C.V., Marquis, R.J., Peterson, G.E., and Ross, D.A. 1947. Hearing aids, an experimental study of design objectives. Cambridge, MA: Harvard University Press[[1]]. This was supported in a concurrent study in the United Kingdom {{2}}[[2]] United Kingdom Medical Research Council. 1947. Medical Research Council Special Report No. 261. Hearing aids and audiometers. London, His Majesty’s Stationery Office [[2]]. Current hearing aid selection procedures are based on “selective amplification,” and, as such, are said to have discredited the findings of the Harvard Report. This approach believes that some unique combination of hearing aid performance characteristics provides for optimal listening for each individual’s hearing loss {{3}}[[3]] Staab, W.J. Hearing aid selection in Sandlin, R (ed) Textbook of Hearing Aid Amplification: Technical and Clinical Considerations, 2nd Edition, Singular, pp 55-135[[3]].
RIC Hearing Aids
In 2004, I presented data on consumer preference results for a deep-fitting hearing aid. (Actually, this was a RIC [Receiver-in-the-canal] concept, even though the acronym RIC was not yet introduced. The instrument was called the PAC, for Post Auricle Canal). This was presented at the American Academy of Audiology Meeting. The investigation related to justification of the RIC, especially when it included a deep-fit design, which all RIC instruments did not do at the time. The reasons for the study were comments being made about the RIC concept, such as:
- A deep-fitting instrument is not comfortable when worn
- A deep fit will not reduce/eliminate the occlusion effect
- It will not look as good when worn as a custom-molded product
- How can sound quality be good if a closed ear system is used?
These comments were generally being made by individuals who had not fitted a deep-canal aid using current technology at the time, or who may have had several years’- old experiences. In some cases, this was the “spin” given to individuals by other dispensers/manufacturers who had not used such fittings or who did not have them in their product offerings.
Subjects
One hundred and four satisfied hearing aid wearers participated in the study. These individuals wore CIC or ITC hearing aids binaurally from multiple manufacturers, and were in the Clinic for routine office visits. Patients were asked if they would like to participate in the study, which would require them to make a comparison of RIC (Receiver-in-the-canal – a fairly new concept) hearing aids with their own hearing aids relative to: comfort, sound quality, sound of other people’s voices, and cosmetic appeal.
The task was for subjects to wear the RIC hearing aids for up to 30 minutes in the busy waiting room. Because all were satisfied (according to the subjects) and experienced wearers of hearing aids, there was no attempt to make an active A-B comparison. They already knew how their hearing aids performed in various situations. All subjects volunteered to make the comparisons. No incentive or reward was offered, and no attempt was made to sell patients a new hearing aid during the demonstrations. The hearing aids used for the study were SeboTek RIC hearing aids, considered the leader in advancing such products at that time.
RIC Settings
The setting and in-office on-the-spot request for patient participation did not lend itself to individualized programming of the RIC instrument. This could have been done, but the purpose of the study was to obtain the requested information in a reduced period of time – while they were in the office. Therefore, the RIC hearing aids were programmed using DSL [i/o] for gradually-sloping audiometric configurations rather than providing individualized fittings, as with the hearing aids they currently wore.
Four patient-selectable memories were programmed as follows:
- Memory One = Programmed in Mute position to facilitate insertion and removal
- Memory Two = Programmed for mild-to-moderate hearing loss
- Memory Three = Programmed for moderate-to-moderately severe loss with a gain increase of 10 dB over Memory Two and other parameters constant
- Memory Four = Programmed for moderate-to-severe hearing loss with a gain increase of 10 dB more than Memory Three, and with other parameters held constant
All patients were given the same hearing aid responses as identified above. Is this starting to sound something like the Harvard Report?
Results
Figure 1 illustrates the results of the study. Comparison results show that, overall, patients preferred the RIC instrument to their own in each of the study questions.
Figure 1. RIC versus custom-molded hearing aid preferences based on a population of 104 experienced, satisfied CIC and ITC hearing aid wearers.
Discussion
Is it acceptable to ask hearing aid patients their opinions about how they perceive hearing aid performance/cosmetic questions? Are they able to make good judgments in such a short time period? Who better to ask than satisfied, existing hearing aid wearers? It has been the author’s experience that patients who have been wearing hearing aids for an extended time period can readily tell when significant changes in their listening perceptions occur. This approach is also a time-tested system for making hearing aid judgments, as is evidenced in multiple hearing aid research studies, as well as making purchasing decisions.
What is obvious from these results, even without statistical analyses and how they relate to the initiative for this study, is that negative comments about deep-fitting hearing aids (at least this RIC type), are not supported. The RIC instrument had the greatest number of patient preferences in each of the four categories.
The only category where the combined results of the preference for one’s own hearing aid and no preference came close to the RIC hearing aid was in the area of cosmetics. This could be understood because the patient was basing this on the way the fitting appeared while looking in a mirror, and was not based on how others see the RIC in comparison to the custom-molded hearing aids. When looking in a mirror the distinction is difficult to make. It is suspected that the results would have been much more favorable toward the RIC if the cosmetic judgment was made by others.
Question 1 – Are RIC hearing aids substantially better in everything they do to explain these results? The answer is a partial “yes,” especially when designed properly. When the speaker is fitted deeply in the ear canal and the tip makes contact with the bony canal walls, the occlusion effect is mitigated, which improves overall sound quality and sound of voices – one’s own and others’. Sound quality is improved with a closed fit, and even more so when the RIC has a response that extends up to 12,000 Hz, which the RIC of the study employed. Comfort comes from the soft tips used on the speakers, eliminating custom-molded earpieces.
What the results show are the general advantages of a RIC over the custom-molded hearing aids used in this study, but such results should generally be expected regardless of which manufacturer’s RIC hearing aids is used.
Question 2 – Are the finely tuned programming approaches used today a case of overkill? After all, the fitting method used for the patients in this study was to have them select from three settings programmed for gradually sloping hearing losses (a la the Harvard Report), with the only difference between them the actual gain level of 10 dB. Still, patients were able to make judgments of significant magnitude. Would the results have been different, meaning even better, if the RIC instruments had been programmed for their losses? Or, were the custom-molded hearing aids not fitted well to begin with?
Regardless, the non-customized RIC instrument preferences for comfort, sound quality, other people’s voices, and cosmetic appeal exceeded those of the customized CIC and ITC hearing aids. These comments are not to suggest that the Harvard Report considerations should become the method of hearing aid fitting, but I cannot help but feel that somewhere Hallowell Davis and his colleagues might be smiling a little.
*In full disclosure, this study utilized the SeboTek Hearing LLC RIC (PAC) hearing aids at the time they were introduced into the marketplace. The office involved was a Clarity Hearing Aids office in Tulsa, OK, owned by SeboTek LLC. The blog author was a consultant to SeboTek at the time of the study.
