Can looking into someone’s eyes tell you how much they are in love? Perhaps, but looking into someone’s eyes can certainly tell you how well they can hear. Broadly speaking, the more hard of hearing someone is, the more eye contact they need to have in order to understand speech. Our brains use both auditory and visual stimuli when we communicate and the worse one of our senses is, the more we rely on the other.

Pupillometry is the measurement of pupil size and reactivity to stimuli. For example, bright light will cause the pupil to contract and low light will cause it to dilate. When it comes to hearing, and accounting for all other reasons why pupil size may change, it turns out that the more challenging the listening situation, the harder it is for one to hear and the more the pupil will dilate.

A standard measure of hearing ability is to measure speech intelligibility, e.g., how many words of a sentence did one understand? Although this is a valid measurement, it does not tell us about cognitive effort. How hard was it for you to get all the words correct? This is where pupillometry is very effective as an objective measurement tool.

Hearing researchers use pupillometry to measure the effectiveness of new hearing aid technology, especially how the technology performs in difficult listening situations. At Resonance Hearing Clinic, when a manufacturer presents new technology to the market, we look for pupillometry studies to help wade through the marketing hype and help determine how well the new technology will help our clients.

So, the next time you look in someone’s eyes, do it with love and make sure they can hear you.