Hearing and Hearing Loss – The basics

Hearing and Hearing Loss – The basics


Hearing is the ability to detect sounds in everyday life and listening is the ability to interpret them – e.g. follow conversations in a noisy environment.

Loudness (intensity+ This is often measured in terms of hearing level (dB HL) – louder sound, higher number) and pitch (frequency+ Frequency is measured in kilohertz (kHz) – higher pitch, higher number) are two basic properties of sound. People with a hearing loss might experience difficulties

  • with quieter sounds or pitch, or both
  • in a quiet or noisy environment, or both

Any reduced sensitivity to sound can have a negative impact on quality of life. Click here for an example

Audiometry tests hearing acuity. It measures sensitivity to pitch and loudness under specified conditions. The test produces an audiogram. The audiogram compares an individual’s hearing sensitivity to a reference standard of ‘average hearing’. The audiogram does not define whether an individual will benefit from a specific intervention. A Hearing Care Professional needs to record history and symptoms, perform audiometry and other tests before it is possible to understand an individual’s hearing ability and address their communication needs.


Hearing loss can be

  • unilateral or bilateral
  • temporary or permanent, and
  • stable or progressive.

Sensorineural and conductive are the names given to the two main types of hearing loss

  • Sensorineural+Sometimes referred to as presbycusis, sensorineural hearing loss is when the tiny sensory hairs in the ear wear down – often as a natural part of the ageing process. The effect of this is different for everyone. For some people it means that although they can hear most sounds, they seem muffled or distorted; some can hear well when it’s quiet but struggle when there is lots of background noise; some struggle to hear particular sounds; or some people can’t hear any sounds at all. Whilst sensorineural hearing loss is a normal part of ageing, we don’t have to accept it. Research shows that over 40% of over 50-year-olds suffer some form of hearing loss, whilst over 70% of over 70-year-olds do. The majority of people with presbycusis can have their hearing and quality of life enhanced with simple forms of hearing support, such as a hearing aid. hearing loss accounts for more than 90% of all hearing loss in adults. In most cases it is permanent and there is no medical or surgical treatment1. Age-related hearing loss is the main cause of sensorineural hearing loss2.
  • Conductive+This can happen when certain sounds can no longer pass freely into your ear. It can happen because of a blockage, for example from earwax or something trapped in your ear. It can also be because of a medical condition like an ear infection, or ruptured eardrum. Conductive hearing loss can cause sounds to become quieter and can often be treated and cured with medical management. hearing loss accounts for 8% of hearing loss in adults. There is often a mechanical cause – e.g. impacted wax, perforated eardrum3. It is usually temporary, but can be permanent. There are medical and surgical treatments for certain forms of conductive hearing loss.

People that have a sensorineural and conductive hearing loss are said to have mixed hearing loss.

An audiogram – the results of a test usually performed by a hearing specialist – can be used to classify whether somebody has sensorineural, conductive or mixed hearing loss. The hearing specialist can also assess the ear using other tests – e.g. tympanometry and otoscopy – to help confirm the type and cause of hearing loss, and decide whether a referral to a medical colleague is required.

Disorders of central auditory processing, also known as auditory processing disorder (APD), can result in hearing difficulties.  In these cases the audiogram is normal but individuals might complain about not being able to hear clearly. Prevalence data for APD is both variable and scarce*For example the Canadian Interorganizational Steering Group for Speech-Language Pathology and Audiology “Prevalence rates of auditory processing disorder in both children and adults have been difficult to confirm, and reports in the literature are inconsistent. Intuitively, prevalence rates should differ across age of the population; overall, the research suggests that audiometry process disorder is relatively infrequent in children and young adults, but quiet common in adults with brain injuries, (for example, with traumatic brain injury in veterans), and very common in seniors”. Ref: Canadian Interorganizational Steering Group for Speech-Language Pathology and Audiology 2012. Canadian Guidelines on auditory processing disorder in children and adults: assessment and intervention. It is estimated that 0.5% to 1% of the population have APD, with a higher prevalence in children – e.g. some estimates suggest a prevalence of between 2% and 7% in children4. One research project from the UK reported that APD might make up 5.1% of the caseload in children’s audiology, but just 0.9% of the caseload in adult clinics5.