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Digital Hearing Aids:
First introduced in the U. S. market in early 1996, the 100% digital hearing aid continues to offer an exciting answer to the question, "What's next?" At the end of the '80s and in the early '90s, we started seeing dramatic new technologies, both multi-band and multi-memory programmable hearing devices. Through automatic means or manual adjustments and remote controls, we could finally help a person to maximize hearing ability in different situations. These types of choices are still available, and can provide good solutions for many users. But some didn't like the manual adjustments and some didn't care for the remote control. And there were always those people who were strongly motivated to hear the best they could, asking "What's new? Is anything better available?" With digital technology, a computer in the hearing aid can sample incoming sound over one million times per second, and update the hearing aid's output 32 thousand times per second. With previous devices, the dispenser could modify four or five parameters in traditional aids, perhaps ten or twelve in programmable aids. In the digital domain, however, more than a hundred different parameters are adjusted. Digital technology can make very complex decisions with extraordinary speed, automatically. Digital technology has revolutionized the way hearing aids process sound, just like CD players have changed how we listen to music. With digital technology, listening comfort and speech clarity can be provided automatically, with over one million adjustments per second. Almost all digital hearing aids are programmable, which means that the audiologist uses a computer to initially set the devices for your hearing loss, and to subsequently fine-tune and personalize them to your particular needs as you use them. As an audiologist, I first began fitting digital aids in February of 1997. I asked many users of existing high quality programmable products to compare the performance in a listening demonstration. Three ordered the digital hearing aids on the spot and three said they would be back within three months (and they did return). These were people who had been wearing hearing aids considered to be some of the "best on the market." Comments like "quieter", "I hear the traffic, but I can hear you much more clearly", and "my voice sounds more natural" got my attention. Were there any failures among those who have tried the digital aids since then? Of course. About 5% of the aids taken out on trial were returned or exchanged for other new products which provided better individual solutions. One kind of instrument is not best for every person, and everyone doesn't need digital or programmable aids. You hearing loss is as individual as your thumbprint. Many factors including your audiogram, anatomy, environment, and personal preferences and expectations influence the one you'll be most satisfied with. I feel that one of my strengths as a dispenser is matching the product to the individual person. To learn more about how digital instruments can be better, schedule a listening demonstration. The extraordinary difference is easier to hear than it is to describe. Digital versus digitally programmable: What makes a product "digitally programmable" is the ability to connect it to a computer and fine tune the way it performs for each individual patient. This characteristic makes it re-programmable if your hearing changes, a very useful feature. Digitally programmable hearing aids may have multiple memories, remote controls and various modes of sound processing (even digital), but it is the ability to change the settings with a computer which classifies it as "digitally programmable." Although they are programmed digitally, they process sound in an analog fashion. True digital processing in hearing aids has only been available in the U. S. since January 1996. Until 1998, the only "100% digital" processing aids were the Widex Senso and the Oticon Digifocus. Since then all manufacturers scrambled to come on line with their own digital products. We can expect continual improvements in digital products from now on. True 100% digital hearing aids are different in that once they are disconnected from the programming computer, a tiny computer chip within the hearing aid itself applies continuous digital processing to incoming sound. In premium products the computer in the hearing aid can make as many calculations and adjustments to sound in seconds as a 486 desktop computer, in instruments as small as the completely-in-the-canal (CIC) size. These "100% digital" aids are also "digitally programmable", since we use a computer connected to the aids to tell a computer in the hearing aid what to do with sound when it is disconnected from the programming computer. No wonder people have been confused! Performance of digital hearing aids varies. Here are some important questions to ask yourself. What is your top priority: performance, appearance, or cost? Knowing that, I can eliminate many choices right from the start, and focus on those things that are important to you. Are you primarily communicating in a quiet, one-to-one environment, or do you lead an active social life? What are the most important things you feel you need to hear better? When you're with other people, what sort of activities are you involved in? Would it be helpful to you to make sounds behind your head softer than sounds in front of you? How do you hear on the phone? Do you use a digital phone or cell phone? How do you feel about a volume control, remote control, automatic sound level adjustment, battery life, durability? The answers to these and other questions help me know which products to consider. With respect to digital aids, all digital processing aids offer less distorted sound. It is quite likely that within a few years, all new hearing aids will be digital. As of 2004, 83% of the new hearing aids fit contained digital processors of some type, compared to 27% in 2001! Today's products offer varied options, with unique internal computerized instructions for how to process sound. These options and instructions are what differentiate one product from another. Options also dictate the degree to which the audiologist can customize the features to suite your individual needs. And, no surprise, the most expensive digital products are the ones that give you (and me) the most options for fine-tuning. They also offer you the finest available hearing correction. Digital hearing aids, a primer. All digital hearing aids are not the same, which is why they have such a broad price range. But if an entry-level DSP hearing aid meets your needs and expectations, it can provide hearing improvement at a comparable price to quality analog products. And the possibilities just get better from there. Directional microphones, which make sound behind the listener softer, remain the best way to increase the signal-to-noise ratio to help hearing aid users hear better in noisy environments. Directional microphones used to be available only in behind-the-ear or large in the ear instruments. Now they are available in all sizes except the tiny completely in the canal size! And some aids change to directional microphones in noise automatically, so you don't have to fuss with buttons. Noise suppression also has many variations and improvements. A few new products can actually reduce two to four sound sources (like the water running and the whirr of the microwave) at the same time, making it easier to converse in real-life environment with several annoying sound sources, like a kitchen. The big trend in premium digital products today is sound processing using "Artificial Intelligence", allowing the chip to make multiple, parallel real-time noise suppression and directional decisions, always with the objective of enhancing speech perception in that particular moment and in that particular situation. The first product to exhibit this was the Oticon Syncro, which has performed very well! Over the past six months, most of the major manufacturers have developed "me too" products, because they recognized that this type of decision-making strategy was more effective in enhancing speech perception for most users. Better digital feedback suppression systems have allowed us to give users more power in the high frequencies, where the clarity of speech lies, without annoying feedback or whistling. This improved feedback suppression, in turn, has fostered the introduction of several new products which can be fit with the ear extremely open and unplugged, providing more natural sound quality and better quality of your own voice, without feedback or whistling as a trade-off. Power versions of these products have also been developed in the past year. Two products I have been evaluating in recent months are the Siemens Acuris and the GN ReSound Metrix. Both look promising. Each has its individual unique points. So if you're confused about the new hearing aids, don't feel bad. So am I sometimes. But by studying them and learning the subtle differences among them, I can help you select the one that seems best suited to your particular needs and expectations. My categorization for digital products goes like this. Premium digital products process sound in nine to fifteen frequency bands, automatically making constant, minute adjustments for soft, medium and loud sounds in each of these bands. These products have true noise reduction capabilities. This means they process speech and non-speech differently, with the goal of keeping the speech signal louder than the non-speech. This does not mean disappearing the background noise (i.e., traffic, air conditioning, silverware, dishwasher sounds, etc.), but rather making it softer than the speech. The way premium digital products accomplish this preserves speech clarity in noisy environments better than any other products (for most users). Digital aids also tend to have special features to control feedback, enhance soft speech, and in many cases, allow directional hearing. Many have multiple settings for varying environments. Some products exercise these options automatically, while others allow user control with a button on the hearing aid or a remote control. Some digital products have manual volume controls. A manual volume control is not always necessary, since the sophisticated processing reads the sound input and controls it automatically on many more levels than a conventional, volume-controlled aid can. Non-premium digital products have varying degrees of adjustability and less distorted sound than conventional aids. In an effort to offer digital at a reduced price, manufacturers have reduced the whistles and bells, while maintaining many of the sound quality benefits of digital sound processing. Some of the features commonly eliminated or delivered at a less-adjustable level are the speech vs. non-speech noise reduction, and flexibility and number of multiple memories There are also some entry-level digital products which do not truly distinguish between speech and non-speech inputs as they process sound. In general, even, non-premium digital products perform significantly better than most of their analog counterparts. It is important that you, as a consumer, understand that all digital hearing aids are not created equal. You won't get all the capabilities you've heard advertised in every digital product. But there are wonderful, affordable choices out there now which can significantly improve your hearing. Directional microphones To find out whether digital processing or directional microphones can help you hear better, make an appointment with your audiologist for an updated audiogram and consultation. In many cases you can listen to a demonstration of the product in our real-life surround sound audio-visual room, and hear the difference for yourself. At Anaheim Hearing Center our goal is the same as yours: to find the very best solution possible for your hearing problems. How technology can help in a restaurant or other noisy environment: In this same noisy environment, digital noise reduction can add another level of improvement. In premium digital products, the instrument listens in 9 to 32 frequency bands and makes a separate calculation for each band. If the incoming sound in that band has more interfering non-speech (dishes, music, air conditioning, etc.) than speech, the volume in that band is automatically reduced. If that band has predominantly speech information, the volume in that band is maintained. The result is that speech information remains louder than interfering non-speech input, which is what it takes for you to understand in the presence of noise. This feature is now available in all sizes of digital hearing aids. The combination of these two features can take you a long way toward enjoying conversations in noise again. Facts and myths about digital hearing aids. Myths: Digital hearing aids do not deliver miracle processing, true high fidelity sound like a CD, perfect compensation for everyone, optimal performance for everyone in all environments, perfect hearing in a reverberant room with poor acoustics. Is digital for everyone? Not necessarily. It depends on your hearing loss and your expectations. Are they susceptible to breakdown due to wax and moisture, like other hearing aids? Yes. Are they superior to anything we've ever had to offer? Definitely yes! Schedule a listening demonstration and decide for yourself. What makes one digital aid different from another? They all convert sound to digital information, process it, and restore it to analog sound output. Digital processing allows sophisticated real-time processing not possible in conventional analog circuitry. One of the things differentiating one manufacturer's digital products from another is the instructions within the digital chip in the instrument about how to manipulate sound. Some products give reduction of noise interference a high priority, while others give clarity of speech the highest importance. Future improvements in digital instrument performance will revolve around better instructions or algorithms for how to manipulate sound most effectively. All manufacturers are rushing to introduce their own digital products. In some cases, digital processing is used to recreate formerly popular analog processing strategies. In other cases, completely new processing strategies possible only with digital technology are being created. For more information about specific products, visit the following manufacturer websites. A "sound picture" is worth a thousand words. When you schedule your personal listening demonstration, we'll program the most appropriate digital instrument for your hearing loss and then step outside into the traffic noise or recreate a noisy envrionment in our surround-sound audio-visual room and converse with you. You'll immediately experience the difference digital processing can make in your life! If you like what your hear (or don't hear), and want to try a 100% digital product on a 60 day evaluation basis, a future appointment will be set for a complete evaluation. More extensive information about digital products will be available for you to take home with you. If your needs and expectations can be met better by a product other than 100% digital, we can discuss the options when you are here. Our goal at the Anaheim Hear for Life Center is to keep you fully informed of all your options, and to set realistic expectations for hearing help. |
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