Those of you wearing hearing aids for many years may wonder why hearing aid batteries do not appear to last as long as before. It’s primarily due to the innovation in hearing aid technology; today’s hearing aids are essentially complex processors. They require significantly more power than the old Analogue hearing aids of years past. These processors analyse sound and make decisions through sophisticated processing. For example, when wearing hearing aids in background noise environments the signal processing is going to be activated to:
In these situations, the current draw from the battery will increase substantially. And if you add in wireless audio streaming on top of that, you might see the current drain double or even triple. Other features that contribute to increased battery drain include technology that communicates between the right and left hearing aids, as well as CROS technologies that stream data between devices.
In situations where these features are not as active, there is less current drain from the battery. For example, take a week when you are home and it is quiet. You may watch television, and have one-on-one conversations with your spouse. Your hearing aid battery may last the entire week. Then, the following week you attend a family reunion, out and about a lot, and go to a sporting event. Your hearing aid battery life may only be five days because of the change in your lifestyle and the demands on the hearing aid signal processing.
Battery life is going to vary between both patient use and hearing aid type; two patients using the same hearing aid won’t necessarily have the same battery life. It depends on the hearing aids’ settings, what features are active, how many hours a day they use the devices, and the environments that they are in. Obviously, a patient who wears hearing aids for 16 hours a day is not going to have the same battery life as one who only wears hearing aids for 8 hours a day. In addition, it is very common that the batteries in a binaural set of hearing aids will last different amounts of time. That’s because if the loss is different between the ears, then the programming between right and left hearing aids is different. This impacts battery life. So there are many individual factors to consider.
The good news is that hearing aid manufacturers are very conscious of the demands on battery life with the introduction of new hearing aid features. For example, hearing aid manufacturer Phonak, launched this year, the Venture range of hearing aids which boasts a doubling of processor power to facilitate the introduction of next generation technology automation, while also reducing the battery consumption by as much as 30%.
When our Audiologists fit hearing aids, patients go through a period of acclimatisation where they become familiar with the functions of their hearing aids and the sounds they have missed as a result of their hearing loss. During this period we recommend that they follow the Manufacturers guidelines regarding battery life and when to change batteries. Over the following months it is worthwhile tracking the battery life on a calendar, marking the dates when battery changes are needed. This will give an idea of the average amount of time the batteries are lasting, based on all the individual factors mentioned above.
There are a couple of basic things you can do to make sure you get the most from your hearing aid batteries, such as;
An 8th grade student, Ethan Manuell in Rochester, Minnesota, USA, who wears a hearing aid in his left ear, began a study[1] with the help of his audiologist, looking into how he might extend the lifespan of his hearing aid batteries. Perhaps he too didn't believe! The study Ethan undertook was with the standard zinc air hearing aid batteries. Zinc-air cells work like conventional batteries in that they generate electrical power from chemical reactions. But instead of packing the necessary ingredients inside the cell, zinc-air batteries get one of their main reactants-oxygen-from the outside air.
So to the science![2] When the sticker is removed from a new battery, oxygen molecules enter the cell through tiny holes in the top and come into contact with a positively charged electrode (cathode) made of porous carbon. Water and other molecules already present in the pores of the electrode react with the oxygen to produce hydroxyl. These molecules, and other pre-existing hydroxyls, migrate through an air separator to a negatively charged electrode (anode) that consists of a zinc gel. The hydroxyls bond to a zinc molecule to form zincate, which immediately splits into two hydroxyls, a water molecule and zinc oxide, and releases two electrons that travel through a circuit to power a device such as a hearing aid.
The student undertook trials and found that the optimum activating time for the battery, (i.e., the time from when the sticker is removed from the battery and placing the battery in the hearing aid), was five minutes. The results showed that the lifespan of the battery would be increased a further 2 – 3 days. Significant when you consider the original lifespan of the hearing aid battery!
In case you are thinking of leaving the activation period for longer, resist! The only downside of the zinc-air battery is that constant contact with ambient air can either dry up the zinc gel or, if conditions are too humid, flood it with water vapour. Both render the battery less potent. Another point is that battery performance may vary between manufacturers.
[1]http://kimt.com/2015/05/05/student-makes-discovery-when-it-comes-to-extending-hearing-aid-battery-life/?fb_ref=Default&fb_source=message
[2]http://www.technologyreview.com/article/401188/zinc-air-batteries/
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earpeace™ is a privately owned Irish Company, with its head office located in Galway, Ireland. The company is committed to providing exemplary audiology services and associated world leading technology products to its customers throughout Ireland. For further information about the company, please follow this link.