Hearing Aid Technology and Features
Starting in the late 1990s through the early years of this century, the hearing aid industry made the conversion from analog technology to digital technology.
By going digital, many of the features most helpful in today’s hearing aids were made possible. With each generation of technology, two of the most helpful features, feedback (squealing) reduction and managing background noise, are improving. These, as well as other features, are not perfect, but are much more effective than they were even five years ago. With today's technology, hearing-impaired people can hear and understand speech in noisy environments that was not possible previously.
Here is a list of the most effective features that will assist you in researching for your next pair of hearing aids
- Feedback reduction
- Feedback is the squealing sound you get when a microphone picks up the sound emitted by a sound system’s speakers. Think of an auditorium when you get a loud squeal through the speakers. A hearing aid does the same thing when sound from its receiver (speaker) is leaked to its microphone. The newest-technology hearing aids have the best versions of this very important feature. Further improvements are allowing more severe hearing losses to be fit with open-ear hearing aid technology, where previously only custom in-the-canal options were available. Efficient feedback reduction also helps custom hearing aids fit more comfortably by not requiring a super-tight physical fit in your ear canal.
- Noise reduction
- Noise reduction can be very beneficial. In the hearing aid world, noise reduction refers to the ability of the hearing aid to not amplify certain sounds under certain conditions. It does not actually remove any sounds (unlike, for example, noise canceling headsets, which introduce an inverse-phase signal that actually cancels out sound). Reducing the effect of sounds, like road noise in a vehicle or the fan sound in the office, can greatly improve your overall comfort as well as improve your ability to understand speech. It can interfere with listening to music, so you may have to make adjustments to the settings to listen to your favorite music properly.
- Channels and Bands
- There is a lot of confusion in the hearing aid industry relating to channels and bands. Simply put, channels affect how the hearing aid operates; bands affect how the hearing aid is adjusted. In general, having more channels is better than having more bands, and the more channels the better – to a point! Research has shown that more than eight channels offers marginal improvement. More important than the actual number of channels or bands is what the hearing aid is doing with them. In other words, don’t place too much emphasis on these numbers. The more noise you regularly experience, the more you will benefit from a greater number of channels and bands.
Channels are sections or slices of the frequency spectrum that are processed more or less independently by the hearing aid. For example, if a hearing aid has eight channels, it will divide up the sound into eight separate sections and each section can be processed independently from the other seven. This is useful for automatically adjusting to a variety of sound environments. Usually the audiologist or hearing specialist can make some changes to the channels for the management of loud sounds.
Bands are used to adjust the hearing aid’s amplification characteristics and for fine-tuning the hearing aid to the wearer's loss and preferences. Hearing aids can have a band for each channel or multiple bands per channel. Like channels, the audiologist or hearing specialist can adjust these bands to the wearer's preference.
- Directional microphones
- Directional microphones remain one of the best tools to hear a single voice in a crowd of people or other noisy environments. As the name implies, they amplify sounds from certain directions more than sounds from other directions – usually they will amplify sounds from in front of the wearer more than in other directions, although recent technologies are improving on this directionality. This technology is seeing big improvements with integrated adaptive technology. A significant drawback is that directional technology alters the natural sense of where sounds are coming from, which can actually hinder the wearer's ability to understand speech. For this reason, it is a good idea to get a hearing aid with multiple memories where you will have access to a program that locks the microphones in an omni-directional mode.
- Automatic Telephone Switch (also known as Automatic Telephone Response)
- This feature can be a big help in understanding telephone conversations. The hearing aid senses the magnetic field of standard, landline telephones and automatically switches to a program (or setting) that is optimized for listening on the telephone. Typically, this means more volume in the lower frequencies and less volume in the higher frequencies to limit or prevent feedback. Keep in mind, this feature does not work well or at all with cell phones and cordless phones.
- Sudden impact sound limiting
- Loud or sudden noises used to get amplified by hearing aids the same way voices do. Imagine a waiter who drops a full tray of dishes right next to your table, then amplify the sound two or three times. This is an example of why sound limiting is an important feature. This feature is helpful to make hearing aids more comfortable in areas where loud sounds, like a dropped dish or slamming a door, might occur.
- Wind noise limiting
- Wearing hearing aids outdoors on a breezy day is much more enjoyable with hearing aids that incorporate a wind noise limiting feature. This feature reduces the annoying sound of air blowing across the microphone (just like using a cordless phone or cell phone outside).
In addition to the features listed above, which are fairly standard in most of today's hearing aid models, below are some features and accessories that are available in some top of the line hearing aid models.
- Remote controls
- Not entirely new, remote controls are getting smaller and have newer, more advanced capabilities. For hearing aids too small to incorporate any switches or dials, the remotes can give the ability to change volume and select between multiple memories or programs – each designed to work best in a specific environmental setting: normal, noisy, music, telephone, etc. A few give the ability to adjust the tone, sharpening the tone for better speech discrimination in noise and backing it off for a rich sound in normal or low noise environments.
- This technology is probably consuming research and development money faster than any other as of this writing. Some of the top manufacturers have made Bluetooth available by using their remote control to sync with a Bluetooth phone or other audio device. The remote then streams the signal wirelessly into your hearing aids. This technology is only worth the price if you currently spend a lot of time on the phone and experience trouble understanding speech.
Some people wonder why you have to use an adapter to get Bluetooth signals to your hearing aids. The reason is power requirements. Although Bluetooth uses a very low power signal, it demands more power than the tiny batteries in a hearing aid can support. The Bluetooth adapter takes the Bluetooth signal and converts it to an even lower power technology that your hearing aid can process without using up its battery too quickly.
Smarter Technology Working Together (Integrated Adaptive Technologies)
The sound processors used in hearing aids are getting smarter with each new generation. Input sounds are analyzed and classified before they get amplified. Sounds that don’t meet the manufacturer’s criteria to be classified as speech don’t get amplified as much as those sounds that do meet the speech criteria classification. Most of the standard features listed above are now being made adaptive so they operate automatically. Integrating these new adaptive features creates continuously improving sound processing. The wearer hears more of what he or she needs to understand, speech, and hears less competing noise, like crowd roar, paper ruffling or silverware clacking.
Typically, when a manufacturer has a new generation of technology it is released in a series of technology levels (often three or four). Although the circuit and exterior are generally identical, the technology levels have varying prices and capabilities.
Comparing Performance Across the Various Technology Levels
All technology levels will sound about the same in quiet to medium noise environments. The top-level hearing aid will perform for better in a crowded restaurant, considerably better than the low-level, but only marginally better than the intermediate level.