President’s Message: Isomorphism and Clinical Decision Making

This article is a part of the September/October 2026, Volume 38, Number 5, Audiology Today issue.

Isomorphism is a concept that appears in mathematics, computer science, and organizational theory. It means that two apparently different systems can share a similar underlying structure or set of processes. Consider this simple algorithm for keeping a rocket on course:

Input: Current position

Evaluation processor: Define variance (current position versus desired position)

Output decision: If variance >0, course correction is required

Action: If course correction is required, effect course change; if not, maintain course

The same process is used in medicine and in audiology:

Input: Subjective data (demographic, chief complaint, onset and progression of primary and co-occurring symptoms, history, other contextual data, etc.); objective/behavioral data (physical exam, test results).

Evaluation processor: The audiologist completes three evaluation processes:

First, compare the obtained data against expected patterns for normal auditory functioning and the various types and causes of auditory disorders and diseases. One pattern will be more likely than the others. This evaluation informs the first key decision point: What is the likelihood that this person has a worrisome disease process?

Second, compare the collected data against the patient’s auditory complaints. Can the problems described in the patient’s complaints be reasonably explained by the observed hearing loss? Is there evidence in the subjective interview, questionnaire data or formal speech-in-noise testing that the person is experiencing “proximal” activity limitations (i.e., directly related to the hearing/communication problem) (National Academies of Sciences, Engineering, and Medicine, 2025) or listening difficulties? Or are they experiencing more “distal” avoidance behaviors (i.e., downstream effects on daily life or participation) or participation restrictions? The key decision point: What is the likelihood that this person can benefit from audiologic rehabilitation?

Third, evaluate the likelihood of
future risk to hearing health or wellness
(Humes et al., 2024). For example, is there a history of noise or ototoxic exposure, diabetes, alcohol abuse, or a family history of progressive hearing loss? This sets up the last decision point about the need for future follow-up.

Output: The audiologist’s decision for each of the three key decision points. These judgments are the product of training and cognitive work. They result in the assessment statements mentioned in my message in the January issue of Audiology Today. Briefly, is there a need for medical referral, audiological management, or other health or hearing maintenance planning?

Action: The management plan develops lawfully from the audiologist’s assessment and is executed in collaboration with the patient. The audiologist’s impressions determine whether to refer or not, treat or not, and plan for future hearing and healthcare needs. This also facilitates care coordination. It communicates to other healthcare providers which problems you will manage and why you might refer for additional services. The real value of your audiological evaluation to your patient and the healthcare system is captured in this isomorphic algorithm. You effect a course correction in your patient’s life.

With a little reflection, you might recognize that you always go through the evaluation process before initiating any audiologic intervention. The context may change (i.e., adult hearing evaluation, cochlear implant reprogramming, repositioning for benign paroxysmal positional vertigo, repairing an earmold), but the process is the same. The process is isomorphic. It captures the elements of the SOAP (Subjective, Objective, Assessment, and Plan) structure and, I would argue, serves as the foundation for documenting the audiologist’s clinical decision-making, including the development of a care plan. Further, when this service is provided and clearly documented in a SOAP note, a fee should be charged. Yes, even a lowly office visit fee. How can a rocket ‘course correct’ without an evaluation process? It can’t.

When I talk about this with other audiologists, I hear several common concerns:

“I work in a physician group. They only want me to list test results as my impressions.” My answer is that physicians are asserting responsibility for managing their patients. Their documentation is in SOAP format, and within that context, the audiologists’ test results are simply objective or behavioral data. This is not a bad thing. Audiologists provide an important, highly technical service in the ear, nose, and throat clinic. But this is not managing patients in an independent, autonomous practice. I speak to the latter.

Another concern is that “my state does not allow audiologists to ‘diagnose’. Your proposed statements appear to cross the line.” My response is that there is a difference between diagnosing ear disease, where “diagnosis” means that a specific disease is present with absolute certainty, and making probabilistic professional judgments about disease risk. Stating an impression such as “the presentation appears consistent with age-related hearing loss” is your professional opinion. It may be right or wrong. It is stated in a way that does not exclude the possibility of an alternative, though unlikely cause. (Pro tip: Don’t be wrong. If there is any indication of an elevated risk of ear disease, explicitly state that the cause is not clear to you and refer.) Ultimately, in every case where you are evaluating someone independently and considering whether a hearing aid or aural rehabilitation might help, you must first decide whether a medical referral or further evaluation is needed. You are licensed. There is no way around it.

David Zapala, PhD
President