A new study raises the specter that as we age, assessing hearing loss is more complicated than just taking and passing a hearing test. A very sophisticated British study matched old and young people with similar backgrounds and hearing test results (Audiograms). It found that the older people, even when tests suggest that they have normal hearing, still had greater difficulty than young people do, especially in noisy environments.
Although this study had a small sample size, it was very cleverly designed: old and young participants were matched by IQ, Audiogram results, education, and other factors (to exclude extraneous affects). The provocative results indicated that older people performed less well on certain hearing tests than younger people do, even when their audiograms were similar or essentially the same. Clearly, the implication is that when it comes to hearing—especially speech processing in noisy environments—the older we get, the less well we do.
What do the results tell us and what are the practical implications? From the research paper: “Taken together, the results show that, even in the absence of hearing loss as measured by the Audiogram, SiN [speech in noise] identification declines with age. Both consonant and sentence identification were poorer for the older participants, but possibly not for the same reasons.” So the research is still incomplete in the sense that we have the experimental data but don’t know the cause! The significance for older people, as the authors state in their conclusions, is this: “These findings indicate a need for clinical tests in addition to the Audiogram when assessing the hearing of older people, and confirm the need to take age into account in studies examining the effects of hearing loss.”
Should we be surprised by this finding? Not really. Although we traditionally think of hearing loss as something that goes on exclusively in the ear, we are finding, more and more, that the ears—like the eyes, the nose, and the other sensory organs—are merely the first step in the process of interpreting external stimuli. After reaching the ears, sound is packaged, transmitted, processed, and made meaningful in the brain. In other words, hearing problems may occur anywhere in the pathway. In fact, as this paper points out, the ear itself could test normal for sound collection and we may still have difficulty hearing.
With the advent of new molecular and imaging technologies, scientists have gained a better understanding of the hearing process. In fact, as a result of this ongoing research, a number of drugs that may help with these problems are in development. More about that soon.