It is very easy to overlook the importance of hearing loss because of how common it is. Hearing loss affects health in the UK more than nearly any other condition (1). However, we are increasingly aware of the consequences of untreated hearing loss - be it depression and dementia in adults, or speech development and educational progress in children.
Hearing loss makes it more difficult to communicate with others - particularly in noisy environments. This can mean adults will avoid such environments, or alternatively communicate less when they are in those environments. That reduction in contact, or the loss of variety in the people you see, is one of the reasons that hearing loss is so closely linked to be depression and dementia (2). If children can not hear speech clearly, then it becomes very difficult to develop speech. The situation is worse in noisy environments, where it becomes more difficult to hear, as it is for adults. Schools are often noisy environments, and hearing loss that is not treated frequently affects progress and behaviour in school (3).
We divide hearing loss into ‘conductive’ hearing loss and ‘sensorineural’ hearing loss. In ‘conductive’ loss, the problem is caused by sounds not being able to get to the hearing organ (cochlea). If you put your fingers in your ear, you can mimic a mild conductive hearing loss. ‘Sensorineural’ loss occurs when the hearing organ itself becomes less good at detecting sounds.
We can tell the difference between these by testing hearing using sounds presented normally - through air into the ear canal using headphones; and then also testing hearing by sending sounds to the hearing organ directly, by vibrating the bone of the skull. As this does not rely on the ‘conductive’ hearing pathways, and we know what loudness sounds most people can hear, this lets us work out which type of hearing loss is causing the problem.
This difference between the two is important, as there is much more we can do for conductive hearing loss. When there is a problem with the ‘conductive’ pathway, it is usually possible to do an operation to fix it. This may involve draining fluid from the ear, fixing a hole in an ear drum, or putting the hearing bones back together. Sensorineural hearing loss has more limited options - it is most commonly treated with hearing aids, although cochlear implants may be used when the hearing loss is severe.
Testing hearing in children can be more difficult. Most hearing tests involve the audiologist playing a sound and asking if you can hear it. Children, especially those under 5, are less reliable than adults at this! Sometimes two people are needed to do the test, and it involves playing a game, or having something fun to look at.
There are also a number of ‘objective’ hearing tests. These don’t rely on you choosing to respond to a sound, but rather they detect your body’s responses to hearing a sound. The most common types of these are ‘OAEs’ which detect hair cells moving in the cochlea (these are the tests most commonly used on newborn babies), and ‘ABR’ or ‘Corticals’ which detect the response of the brain to a sound. The video below gives information about hearing testing at Great Ormond Street.
References:
1. Global, regional, and national incidence, prevalence, and years lived with disability for 328 diseases and injuries for 195 countries, 1990-2016: a systematic analysis for the Global Burden of Disease Study 2016. GBD 2016 Disease and Injury Incidence and Prevalence Collaborators. Lancet. 2017 Sep 16;390(10100):1211-1259.
2. Dementia prevention, intervention, and care: 2020 report of the Lancet Commission. Livingston G, Huntley J, Sommerlad A, Ames D, Ballard C, Banerjee S, Brayne C, Burns A, Cohen-Mansfield J, Cooper C, Costafreda SG, Dias A, Fox N, Gitlin LN, Howard R, Kales HC, Kivimäki M, Larson EB, Ogunniyi A, Orgeta V, Ritchie K, Rockwood K, Sampson EL, Samus Q, Schneider LS, Selbæk G, Teri L, Mukadam N. Lancet. 2020 Aug 8;396(10248):413-446.
3. Childhood Sensorineural Hearing Loss and Educational Attainment in Adulthood: Results From the HUNT Study. Idstad M, Engdahl B. Ear Hear. 2019 Nov/Dec;40(6):1359-1367.