How modern hearing aids mimic natural hearing

Hearing aids have come a long way from what they used to be. Compared to the large devices that people with hearing impairments had to wear, they are now so tiny; very few will even notice that someone is wearing them. The modern hearing aids automatically adapt and synchronize to environmental or user changes to provide you with a natural and intuitive listening experience.

The different styles of hearing aids that people can choose from are:

  • Behind the ear (BTE) hearing devices are positioned behind the ear, where the electronic parts of the hearing aid are encased in a shell behind the ear and the sound travels into the ear through an ear hook or a thin tube.
  • Receiver in the ear (RIC) hearing devices are positioned behind the ear where the hearing aid has tiny housings because their receiver sits directly in the ear canal
  • Custom hearing devices are worn directly in the ear. They are very small, lightweight and tailor-made based on the anatomy of the wearer’s ear. They can either sit in the bowl of the ear of deep in the ear canal.

When listening situations become difficult, we rely on both ears to help us hear well. This is referred to as binaural hearing processes.

3 of the most important processes in binaural hearing include: binaural redundancy, binaural squelch, and binaural directed attention. The first is binaural redundancy, and this basically means that when we hear the same sound with both ears, our brain hears that same sound twice, and this combined perception is better than the individual signal. The second effect is called binaural squelch. When we hear with both ears, our brain is able to give neural preference for speech over noise. The third one is binaural directed attention. Unlike the other two processes which happen subconsciously, binaural directed attention involves conscious intent. When we hear a mixture of different sounds, we can consciously choose to listen to one particular signal while ignoring all others. For example, if you are standing in front of two talkers and only listening with one ear, the speech from each person overlaps. But when you listen with both ears, it’s easier for your brain to pick out the speech source you want to focus on while suppressing the other.

But what happens if we have a hearing loss? And how are these processes affected as we age? Unfortunately, the effectiveness of these binaural processes deteriorates with increasing severity of hearing loss and age. Why? Age-related hearing loss impacts on the audibility of sounds, and also damages the quality of sounds that are heard. And if the hearing loss is significantly different between the two ears, then the problem is even worse. Furthermore, with aging, cognition is affected, which can also be detrimental for speech understanding. Therefore, as a result, our ability to separate auditory signals deteriorates, it takes longer for us to identify where sounds are originating from and we struggle to follow the conversation in noisy situations.

So what is the goal of the modern digital hearing instrument? The goal is to decrease the gap between hearing loss and normal hearing by restoring normal auditory processes including binaural redundancy and squelch in order to improve hearing in challenging listening situations such as background noise, but also ensure a natural sound impression. Binaural hearing only works when the brain has input from both ears to work with.

Modern hearing aids combat binaural hearing problems by linking hearing aids to each other when the wearer has them on.  This is made possible by a unique feature called e2e wireless. The latest versions of e2e wireless systems are able to directly transmit audio signals between the two hearing instruments. So now, each hearing aid in a bilateral fitting knows exactly what the other hearing aid is picking up, and they can make decisions together in regard to signal processing to optimise settings. This means that each hearing instrument in a bilateral pair works with input from four microphones and the sharing of this information between the ears creates a virtual microphone network. This provides a heightened sensitivity of the acoustic environment referred to as High Definition Sound Resolution (HDSR).

Reducing listening effort in most challenging listening situations is another main feature of a hearing aid. Increased listening effort means having to recruit additional cognitive resources, which in turn leads to compromised decision making ability and decreased reaction time. It also results in listening fatigue which leads to a lack of concentration and diminished focus. These effects are detrimental for speech understanding and extremely tiring for the wearer! Luckily modern digital hearing aids with features such as SpeechMaster and Echoshield are specifically designed to decrease listening effort and improve listening ease. But that is not all they are targeting.

SpeechMaster utilises noise reduction algorithms, and alters directionality and amplification characteristics in the hearing instruments to isolate the target speaker directly in front of the wearer and reduce competing speech signals and noise from all other directions. This not only significantly improves speech understanding in noisy environments, but also decreases listening effort. The best part is that it operates automatically, meaning it will adapt and optimise hearing instrument settings depending on the situation you are in without you even realising.

As Echoshield’s name suggests, it is designed to improve hearing in reverberant or echoey environments such as halls, foyers, churches, restaurants – basically anywhere that has hard surfaces and minimal soft furnishings to absorb the sounds so they are not reflected. Unfortunately, a highly reverberant environment is similar to background noise. It degrades the clarity of the signal and leads to reduced speech intelligibility. Echoshield significantly reduces the impact of reflected sounds from hard surfaces and enhances the target speaker.

A common complaint from people with hearing loss, which involves a high degree of listening effort, is hearing phone conversations. When you think about it, this situation is extremely challenging given you are relying on hearing from one ear only, and you cannot utilise any visual cues such as lip reading or facial expression to augment your understanding. Some modern digital hearing instruments have technology which greatly assists in this area. For example, Signia hearing aids have a feature called Twinphone. Twinphone can actually send the signal from the telephone side to the non-telephone side via the e2e wireless system so the signal is heard in both ears! This not only increases the loudness, but significantly improves your ability to decipher what is being said. This would be especially beneficial for people with softer voices or accents. An additional benefit is that this feature is fully automatic. All you need to do is attach a magnet to the phone which then engages the Twinphone feature.

All of these features available in the modern digital hearing instrument combine to offer a sophisticated and holistic solution for the wearer that can also be tailored or customised depending on their individual preferences.

To find out more about Signia hearing aids, head to www.signia-hearing.com.au

 

To get a Quote on Signia Hearing aids click here

 

 

This is a guest post created by Signia for Value Hearing’s use.

 

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