Carhart’s Method

I visited my favorite car salesman the other day.  His dealership was fixing my recalled Takata airbag.  In the course of our conversation, Tom told me that the large automotive group that owns his dealership has purchased the 6 other dealerships in that auto mall.  They probably won’t rename the mall to reflect the large auto group, but each lot will benefit from customers who want to shop around.


Choices are good. So are data.


The car episode reminded me of past efforts of some audiologists who expanded their offices to include devices other than hearing aids.  They incorporated other listening devices, telephones, TV speaker systems, and other stuff that might appeal to and help a hard of hearing patient/customer.  Will these same offices have the nerve to put up displays of PSAPS and OTC choices?

Fifty or sixty years ago, when a HOH patient sought hearing aids, there were essentially two courses of action.  Most often, these individuals visited a retail office selling these devices and found each office sold only one brand of hearing aid.  Single-line offices were the rule back then.  Audiotone, Maico, Beltone, RadioEar, Qualitone, Vicon, and Zenith were the names on the doors.  On fewer occasions, patients visited a clinic offering hearing services.  Audiologists at that time referred to single line sales offices after using the Carhart method of comparing various hearing aids with each patient.

Raymond Carhart, PhD

By the time audiologists entered the retail market in the late 1970s, most retail offices offered customers multiple choices.  The Carhart method of evaluating potential hearing aid benefit in a clinical setting vanished, demo (consigned or trial) hearing instruments in clinics disappeared, and audiology was hooked on the established and successful model of retail dispensing that persists in most offices today.


Face Validity Has Its Place


Criticism has been leveled at these old methods, but there is a lesson from Professor Carhart that we may wish to revisit.  Clinical data—gathered as independently as possible—may be crucial to a patient making the effort to solve a hearing problem.  If not crucial, at least this data may be a significant part of the enabling that patients say they desire. (Recall the FTC hearings.)

In the busy otology office where I worked many years ago, I evaluated 6-8 patients per week with Carhart’s method.  I made referrals to local sales offices with specific recommendations of instruments to be purchased, rented, or otherwise tried.  While I certainly lost clinical control of those patients, I have no doubt that at least some of my recommendations gave these patients a small sense of what today we would call positive enabling.

Enabling a person involves objective data, time and effort, and perhaps participation from others.  Intuitively, there is a direct relationship between each of these factors and the end result—patients feeling empowered. 

The Carhart method of evaluating hearing aids certainly added to patient empowerment.  Patients left the audiology clinic with information about hearing instruments, how they sounded, and how they might help lessen a hearing problem.  Granted, we should have done more, but, at that time, this was all we had. The Carhart method provided data, maybe not all it could be, but data nonetheless.


The Data Changed But the Patients Didn’t


Time passed.  Technology changed.  Devices improved dramatically, as did techniques for gathering data.  Patient empowerment seems to have stagnated, if you believe what consumers and patients said at the FTC meeting in April.1 I hope you are asking “Why?”

In the minds of many consumers, as they complain they are not feeling empowered when investigating hearing aids,they may believe that the information they get from many audiology and physician clinical offices is not sufficiently based in clinical data.  Or maybe not too different from any retail sales source. 

Perhaps Tom, my car friend, could offer some suggestions from the auto sales business.  In his business, customers find some empowerment in “shopping” from various sources, evaluating options, styling, and prices.  Tom likely thinks that, if he offers data, choices, and alternatives, he will gain customers.  Sure, they get a sales pitch, but they also feel “empowered”.

I am not saying that we should revive the Carhart Method of hearing aid evaluations; I am just suggesting that there might be lessons we can still take from Professor Carhart.

  • The first lesson might involve patient choice: Patients chose a “neutral” source of information with Carhart’s method.
  • The second lesson may involve some sort of personal opinion that illustrates the benefits of one instrument over the other. Even if the Carhart data weren’t sufficient, they might have had some positive influence on the patient. (Don’t read any more into this.)
  • The neutrality of the data might have played a role in the recommendation for trial with hearing instruments. The hour or so of interaction and explanation with the patient really constituted the beginning of rehabilitation.

You can probably come up with some other benefits of an independent, data-driven, objective assessment of patient needs, outcomes, and whatever.  Perhaps your contemplation will reveal that you are doing things that help empower patients.Maybe you could do more.  Maybe we abandoned the Carhart method too quickly.




1See the four-part discussions available at Scroll to 2017 workshops and hearing aids.

About Mike Metz

Mike Metz, PhD, has been a practicing audiologist for over 45 years, having taught in several university settings and, in partnership with Bob Sandlin, provided continuing education for audiology and dispensing in California. Mike owned and operated a private practice in Southern California for over 30 years. He has been professionally active in such areas as electric response testing, hearing conservation, hearing aid dispensing, and legal/ethical issues. He continues to practice in a limited manner in Irvine, California.


  1. Two comments:

    1) “Granted, we should have done more, but, at that time, this was all we had” is not quite true: We’ve had the Master Hearing Aid for decades; and in fact it’s still a powerful tool for reverse slope SNHL, as the results are often, shall we say, “surprising” (it shows how every fitting formula blows up with RSHL!);

    2) When I started from scratch in the industry, I asked the manufacturers had a “consignment program” for dispensers. Unfortunately, “consignment” in our industry is totally different than for typical W/D, jobber, and retail businesses, as the philosophy is “you can’t sell from an empty wagon. Basically, I was asking for a 90 day plan where the instruments remain sealed in the package until sold; and at the end of the 90 days either the devices would go back, or the consignment term renewed. In a program such this, demo aids would be in a separate pool, usually purchased at a very low price for the purpose of demo — This is standard retailing 101.


  2. In a nutshell, hearing help is 80% psychology, and 20% technology ! We are dealing with human minds, and not with the product. The product is already existing, and ready to be used, but the human mind is generally too confused about the outcomes and needs education. Changing the plasticity of the brain requires more intelligent interaction with the patient. If not done, then the positive outcomes may be reduced, and that may be the main reason why hearing aids are not sought after commodities!!!

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