How HearAngel works

The Science

The silent epidemic of permanent hearing loss

We started to evolve as humans around five million years ago, with hearing to enable us to communicate and keep us safe. Our hearing hasn’t evolved much since and has not caught up with the technological advances of reproduced sound through amplifiers and loudspeakers.

We use headphones more and more in our daily lives, but our hearing has not evolved to be exposed to these large sound doses and, according to the World Health Organisation (WHO), as a result more than 2.5 billion of us are at risk of permanent, avoidable noise induced hearing loss by 2050.

The biggest source of large sound doses for most of us is from headphones, so new safety standards have been introduced to provide us with information about our sound exposure over time so we can manage it ourselves.

Our ears are an amazing part of the body that help deliver the vital sense of hearing, but they are fragile and easily damaged. Repeated exposure to high sound doses through the use of headphones and earbuds can permanently damage hearing in a way that cannot be recovered.

Until evolution catches up, we need to adapt to this recent increase in sound dose and be aware of our exposure, so we can make informed decisions about our listening and protect our hearing.

We can hear sound because of vibrations (sound waves) that enter our ears that we then decipher. The outer ear directs sound waves into the ear canal where they travel to the eardrum. The eardrum vibrates from the incoming sound waves and sends these vibrations to three tiny bones in the middle ear that amplify the sound vibrations and send them to the inner ear. The inner ear contains a structure filled with fluid called the cochlea. Sound vibrations create waves in the cochlear fluids. As the waves peak, they cause tiny hair cells within the cochlea to bend, which convert the vibrations into electrical signals interpreted by the brain through the auditory nerve.

At birth, humans have about 15,000 auditory hair cells within the cochlea of each ear. These cells are the critical point where the physical noise energy is converted to allow your brain to detect and interpret the sound, with different hair cells able to respond to different ranges of sound frequencies. These hair cells are very vulnerable to irreparable damage by regular, repeated exposure the large sound doses and excessive noise. You don’t get any more and when they are gone they are gone - and so is your hearing. By the time you notice hearing loss, many hair cells have already been destroyed and cannot be repaired or replaced, and worse still this damage can take a long time to show up.

Because we tend to lose the outer hair cells through cochlea damage first, early hearing loss presents itself as a diminished ability to distinguish sound frequencies and therefore the quality of speech or music; we struggle to distinguish and understand speech, particularly when there is background noise. Eventually, if hearing loss continues, it can become hard to understand speech even in quieter places. In addition to damaging hair cells, repeated exposure to high sound doses can also damage the auditory nerve that carries information about sounds to your brain.

The solution to minimise hearing damage from the use of headphone products is to understand the degree to which your ears have been exposed to potentially damaging sound energy, and make sensible, informed choices about how to listen in order to stay within safe limits. The challenge is that the measurement of the sound energy exposure over time is not a trivial matter and certainly not something that can be intuitively gauged: it is a complex combination of listening period (time), how loud you listen (volume) and the energy content (density) of the sound you listen to.

Child on iPad wearing headphones

What are the safety standards?

The highest current safety standard is ITU/WHO H.870 which the World Health Organisation announced in February 2019. In December 2019 the ITU/WHO announced that Apple had integrated the standard into their HealthKit app. An updated version of the standard, H.870v2, is to be published in May 2022.

This standard requires that headphone users are given information about their sound dose and that they acknowledge these warnings, with the latest version of the standard demanding that the sound dose is measured as close to the ear as possible.

The second standard IEC62368 – 1:2018 came into effect in Europe and North America (with other countries planning to follow) in December 2020. This standard provides manufacturers with two options, the second of which is similar to H.870 but less demanding.

HearAngel® when integrated into the wireless headphones can meet both the IEC62368 – 1:2018 and/or ITU/WHO H.870v2 standards.

Why HearAngel®?

HearAngel® is built into wireless headphones to calculate the effect of what users listen to and give them accurate information about their listening habits, notifying them if they are at risk; think of it as a Fitbit for ears.

Users can choose to enable HearAngel®’s protection feature, which will manage their exposure automatically, making sure that they don’t exceed their Daily Sound Allowance® and preventing them from being exposed to harmful sound doses.

Parents or carers concerned about their children’s exposure can activate the parental control feature which will limit the child's peak exposure level, their sound dose and listening period to those selected.