Should Audiology be Concerned with Cognitive Testing?

As part of the fitting process for hearing aids, several pre-fitting tests may be performed.  Experience has shown that speech-in-noise tests such as the Quick SIN or Words-in-Noise or a loudness discomfort level test can help the audiologist get the best results for their patient.  However, recent advances in understanding how the brain processes sound indicate that the fields of audiology and psychology may collide.  That’s because there is more and more recognition of the importance of cognitive function (or working memory) in auditory processing.

Working Memory, Short-Term Memory, and Long-Term Memory 

Short-term memory allows you to keep something in mind (say a telephone number) for a brief period of time until it is either no longer needed or transferred to long-term memory.  Short-term memory is like the front desk attendant for the brain. There are limits to short-term memory, and as we age, the amount of time our brain can store information becomes shorter and shorter.

Long-term memory is where we store “memories” like our wedding day or the smell of a new car.  It is also where we store implicit memories that allow us to do things by without thinking, such as typing or riding a bicycle.

Working memory is the type of memory that is most important to the field of audiology.  This is the memory where sounds get processed.  As the signals come in and are recognized as speech, they get compared and integrated.  Working memory processes and prepares information for short- or long-term storage.

How Processing and Working Memory Work Together

Think of a difficult hearing situation, such as a noisy restaurant.  The listener has to tune into the speaker’s voice and block out background noise.  Then the signal is recognized as language, and the semantics and syntax must be processed. If the listener can see the speaker, the visual cues will need to be integrated. All of this is happening in working memory.

Once the data is matched with stored representations, it can be moved over to long-term memory.  In a quiet situation the processing and storage is quick; in noisy situations it may take longer.   However, if the listener has working memory loss, this processing will be difficult no matter the environment.  Hearing will be difficult in quiet and noisy situations, not because of hearing loss, but because of cognitive function loss.

Measuring Working Memory for Audiological Purposes

One of the better ways to measure working memory for audiological purposes is the Reading Span Test. This test was designed to measure storage and processing capacity of working memory. In studies concerned with speech recognition, it’s usually given as a visual (reading) test rather than an auditory test, so that results will reflect cognitive capacity and not be contaminated by hearing loss.

That being said, don’t be surprised if your hearing aid fitting includes some tests that don’t seem to relate to hearing.  It is just another way that the field of audiology has expanded to give the best hearing opportunity to every person with hearing loss.