Few words about hearing aids

What is a hearing aid ? What is the purpose of a hearing aid ? What can we expect from a hearing aid ? Why are there so many price differences between hearing aids and is this justified ?

So many questions that it is useful to ask yourself before buying these devices. But, if the different brands flood the media with their advertising, the technical explanations and objective performances of each one, the main interest for any buyer, are passed over in silence, as if the latter was judged incapable of understanding and that it was a totally secondary element. Yet this is the heart of the matter ! Could one then advance, paraphrasing the grandmother of a certain political figure that “When it is fuzzy, there is a wolf” ?

What is a hearing aid ?

Schematically, these are miniaturized sound amplifiers, currently analog, which equip the hearing impaired and whose purpose is to vibrate the liquids of the inner ear in order to stimulate the hair cells not destroyed. Whatever the quality of the device, what is destroyed is destroyed. The damage concerns the inner ear, i.e. the sensory organ. One will never regain the hearing of one’s younger years. Let us repeat the absolute necessity to protect one’s ears, throughout one’s life, from environmental or professional noise aggressions.

What is a hearing aid used for ?

A hearing aid is used to amplify damaged hearing frequencies, regardless of the price of the device purchased.

What are all hearing aids made of ?

A microphone

All of them, regardless of their brand, are substantially the same. Often equipped with multidirectional inputs (minimum two), spatially offset, which allow to create a spatial effect. It picks up sounds and transforms them into electrical signals. These microphones have a limited bandwidth. They are therefore the first filter in the quality of the device.

An amplifier

It is a sound amplification and sound processing system. The electrical signal collected by the microphone is transformed by an analog-to-digital converter (ADC) into a series of numbers (digital device). These binary values are then processed by a mathematical algorithm and the numbers coming out of the microprocessor are different from those present at the input. They are then transformed back into electrical current thanks to a digital to analog converter (DAC).

An earphone

It is very small in the hearing aid, inducing distortions all the more important as the amplification will be big. It transforms the modified and amplified electrical signal into a sound wave. It is the second weakest link in the hearing aid because of its size. A consumer walkman will perform better because of the larger size of the earpiece.

The microphone and earpiece should be as far apart as possible in the device to avoid feedback (whistling sound obtained by bringing your mouth too close to a microphone to speak).

What can you expect from a hearing aid ?

The best ! But the best remains imperfect, limited by two points:

The weak link : if an element is of poor quality, it is this element that imposes the overall quality of the device. However, the miniaturization of digital devices imposes microphones and headphones, similar for all, which cannot be compared to high-fidelity devices and which influence the final restitution of the sound. The processor, which is more or less the same whatever the price, will have little or no influence on the quality of the whole.

The part of destruction of the hair cells which is definitive as we have seen and on which we will not be able to act.

Why such a price difference between hearing aids ?

Hearing aids come in all price ranges and users get lost.

It has been said: a hearing aid serves to amplify damaged hearing frequencies. Without exception, all hearing aids, including assistive listening devices, meet these criteria. So why are there such price differences between hearing aids fitted by hearing care professionals and assistive listening devices, which can be found on the market at 300 euros ?

• Hearing aids are fitted by hearing care professionals, the audioprosthesists. Hearing care professionals advise and fit hearing aids according to the patient’s own hearing curve, which is determined by the ENT specialist. This requires repeated adjustments, monitoring of the patient and adjustment of the settings during the life of the device. All curves, especially severe hearing loss, are handled by these specialists.

Source: French Competition Authority, July 2016

“What avenues for improving competition in the hearing aid sector, in France?”

• Listening assistants are pre-set and ready-to-wear hearing aids. They selectively amplify the high frequencies (2,000Hz / 4,000Hz / 6,000Hz in particular) affected by presbycusis. Presbycusis concerns all ageing individuals who are often slow to get hearing aids at the beginning, due to the prohibitive cost (despite the 120 euros reimbursed by the Social Security) and also due to a denial of the handicap (rather male) as well as a questionable aesthetics for the contours. These listening assistants can thus fit all the beginners or average presbycousics provided (for the intra-conduits) that the conduit is not too narrow. They can also be a first step towards hearing aids, preserving the cognitive abilities of patients who are fitted far too late, especially in France (5 million presbycusis sufferers and 15% of those fitted). As their hearing capacities diminish with time for some, but more so their cognitive capacities, they will be able to choose at any time to continue their journey with the hearing aid technicians.

How do patients feel about wearing a listening assistant ?

For almost all of these patients, whom we can meet in consultation and who have made this choice for financial reasons, the feeling is excellent. This is confirmed by e-mail exchanges between specialists1.

However, there are a few rules to keep in mind: the need, for patients who have made this choice, to have the “green light” from an ENT specialist, in order to avoid a bad indication, as is systematically the case for the hearing aid specialist, in order to benefit from the “Sécu” reimbursement.

What will tomorrow be made of ?

This is an interesting question for everyone, but the only consideration is that of the patients.

Unquestionably, an “acceptable” price seems unavoidable, taking into account the elements mentioned above. A bilateral device with Bluetooth could avoid feedback by adapting a microphone in one device and the earphone in the contralateral device and vice versa. Indeed, one of the claims of the hearing impaired of today, as Professor VANECLOO indicates, “is no longer to hear more but to understand better” thus imposing the stereo sound.

In the long term, what will tomorrow bring for all these devices? Will we go towards the ever smaller with the development of miniaturization and better quality? Will we return to a system that favors a Hifi sound with an independent microphone that can be hidden wherever we want and quality headphones in the ears, all connected by a Bluetooth system?

Questions that deserve to be asked because we will all be concerned.

¹ Robyn M. Cox, Jani A. Johnson, Jingjing Xu, 2015
“Impact of Hearing Aid Technology on Outcomes in Daily Life: The Patients’ Perspective”

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