The Influence of Cardiovascular Health on Peripheral and Central Auditory Function in Adults: A Research Review

Raymond H. Hull and Stacy R. Kerschen

Wichita State University, Wichita, KS

Contact author: Raymond H. Hull, Wichita State University, Department of Communicative Disorders and Sciences, Wichita, KS 67260-0075. E-mail: ray.hull@wichita.edu.

Purpose: This article provides a comparative review of research that has been conducted over the past 60+ years on the influence of cardiovascular health on the function of the peripheral and central auditory systems, and findings on the influence of improvements in cardiovascular health on those same systems.

Method: Research spanning the past 6 decades reviewed for this article has both hypothesized and confirmed the cardiovascular system's effects on the peripheral and central auditory systems. A review of the influence of the cardiovascular system is presented in this article, and a potential new avenue for auditory rehabilitation is postulated. The review presented in this article does not represent all studies conducted in the topic area but does provide an in-depth look into this fascinating area of research.

Conclusions: The negative influence of impaired cardiovascular health on both the peripheral and central auditory system and the potential positive influence of improved cardiovascular health on these same systems have been found through a sizable body of research that has been conducted over more than 6 decades. The most significantpositive relationship between improved cardiovascular health and improvements in those auditory systems has been found among older adults. If that relationship continues to be confirmed, then a potential new avenue for auditory rehabilitation on behalf of adults who possess impaired auditory function may be discovered.

Do I Need Two Hearing Aids?

Basically, if you have two ears with hearing loss that could benefit from hearing aids, you need two hearing aids. It is important to realize there are no "normal" animals born with only one ear. Simply stated, you have two ears because you need two ears. If we try to amplify sound in only one ear, you cannot expect to do very well. Even the best hearing aid will sound "flat" or "dull" when worn in only one ear.

Assuming you have two ears that hear about the same, you can do a little experiment at home to better understand how important binaural hearing is:

First, gently close just one ear, by simply pressing the little fleshy part in the front of your ear canal (the tragus) into your ear canal -- a little. Do not apply pressure, do not hurt yourself. Just close the ear canal to eliminate sound from entering the ear. The idea is to close that ear for about ten minutes while you watch TV or listen to the radio, or speak with your spouse. Then, after a full ten minutes, remove your finger. What an amazing difference!

There are many advantages associated with binaural (two ear) listening and importantly, there are problems associated with wearing only one hearing aid -- if you are indeed a candidate for binaural amplification.

Localization (knowing where the sound came from) is only possible with two ears, and just about impossible with one ear. Localization is not just a sound quality issue; it may also be a safety issue. Think about how important it is to know where warning and safety sounds (sirens, screams, babies crying, etc) are coming from. Using both ears together also impacts how well you hear in noise because binaural hearing permits you to selectively attend to the desired signal, while "squelching" or paying less attention to undesired sounds such as background noise.

Binaural hearing allows a quality of "spaciousness" or "high fidelity" to sounds, which cannot occur with monaural (one ear) listening. Understanding speech clearly, particularly in challenging and noisy situations, is easier while using both ears. Additionally, using two hearing aids allows people to speak with you from either side of your head - not just your "good" side!

People cannot hear well using only one ear. There are studies in the research literature that show that children with one normal ear and one "deaf" ear are ten times more likely to repeat a grade as compared to children with two normally hearing ears. Additionally, we know that if you have two ears with hearing impairment, and you wear only one hearing aid, the unaided ear is likely to lose word recognition ability more quickly than the ear wearing the hearing aid.