Hearing Aid Technology

From full wireless capability to digital sound enhancement, hearing aids have come a long way.

Deaf woman using smartphone

The considerable advancement of hearing aid technology in the 19th and 20th centuries can be attributed to three inventors: Alexander Graham Bell, Werner Von Siemens, and Thomas Edison. Bell used a microphone and battery to amplify sound electronically for his new telephone, while Von Siemens invented the first technology-based solution for hearing loss. Thomas Edison, who was hard of hearing, never built a hearing aid himself—in fact, he rather enjoyed his deafness for the solitude it provided. However, his contributions did send shock waves through the world of sound engineering. In 1877, he expanded on Alexander Graham Bell’s early telephone by inventing a carbon transmitter that converted sound into electrical impulses conducted through wires and converted it back again.

Hearing aids continue to evolve

Throughout the 20th, century hearing aids evolved significantly and continued to advance with each passing year. Early vacuum tube technology in the first portable hearing aids from the 1920s was eventually replaced by transistors and microchips, which helped make later devices smaller and smarter.

The first attempts at hearing restoration involved analog instruments, which converted physical sounds into electrical waves that simply made all incoming sounds louder. Consequently, noise, speech, and background sounds were all amplified equally, which made it difficult to discern what you wanted to hear from what you didn’t.

More modern analog hearing aids became programmable, able to be adjusted for different surroundings, such as large public places (arenas), smaller but still crowded rooms (restaurants), or quiet zones (home). These devices incorporated microchip technology that improved the usability of analog hearing aids. Despite their low cost, analog hearing aids were quickly replaced by digital as standard devices because of the wide range of features and settings the latter offer. If you are interested in purchasing an analog hearing aid, be sure that the manufacturer has been approved by the FDA to sell devices proven to assist those with hearing loss, and expect difficulty even finding analog options.

Digital hearing aids elevate hearing to a new level

Unlike analog devices, digital hearing aids receive sound waves and then convert them into digital signals. A computer chip allows the hearing aid to analyze the entire listening environment before deciding which sounds to enhance and which to dampen, all according to preferences programmed for the user or “learned” by the hearing aids through regular use. As a result, sound is clearer and more easily understood than when processed by analog hearing aids.

Each hearing aid has a set limit of equalizing channels that can analyze and modify multiple frequency ranges at once, sometimes making the finished sound richer and denser than what those with normal hearing experience. Directional microphones also aid in the enrichment of sound by turning up the volume on sounds directed toward you (e.g., someone talking to you) and quieting the rest. Think of this feature as the zoom lens on a camera, as opposed to omnidirectional microphones that pick up sound from wide angles.

Hearing loss can be especially challenging when it occurs within the frequency spectrum of human speech, which spans 200-5,000 Hz. For this reason, many hearing aids now can identify situations where speech is highly present and will manipulate incoming sound accordingly by boosting the clarity of sounds within this range. Once a hearing care professional has set up the programs according to your needs, the digital hearing aids can self-adjust in varying situations to match your hearing requirements.

Similar algorithms are used to prevent acoustic feedback, the phenomenon chiefly responsible for whistling and other unpleasant noises emitted by hearing aids of the past. This occurs when excess sound from the amplifier escapes from the ear canal and is picked up a second time by the microphone, resulting in an endless loop. Today, the potential for feedback has been greatly reduced due to digital audio filtering that can recognize when a duplicate frequency is heard and remove it before it expands.

Multiple memories

Digital hearing technology offers a wider range of programmable options than analog to make listening as seamless as possible. Using a remote control, hearing aid wearers can make manual adjustments to their hearing aids when in a new location to fit their needs. Once this information has been programmed, the device will remember the location and certain acoustic features, such as volume and frequency range. This information is added to a database of hearing aid “memories,” and some devices can automatically return to previously set programs if the sound environment is familiar.

Advanced digital hearing aids are also able to record information unrelated to sound, such as the time spent wearing the hearing aids and how often certain programs are used. Over time, these data points add up to construct a detailed overview of how you hear throughout the day, allowing adjustments to be made accordingly. For example, if you always turn up the volume at dinner to hear your family’s conversation, your hearing aid will eventually learn to make this change for you. By taking the time to calibrate your hearing aids in detail, you and your hearing care professional will have a better understanding of how your hearing loss is responding to treatment.

Binaural processing

All animals that hear with their ears are born with two for a reason. The ability to hear sound from different directions allows our listening to be more precise and rounded so we can isolate individual sound streams in relation to the overall field of environmental sound. When hearing damage occurs bilaterally (in both ears), it can become difficult for the brain to determine where sound is coming from. Today’s hearing aids correct this problem with the help of binaural processing.

Binaural processing attempts to replicate how the brain interprets sounds from both ears by synchronizing the behaviors of both hearing aids. This can help prevent one hearing aid from making different adjustments than the other, and allows for the same audio stream to be delivered to both ears at the same time. In situations where wind or noise affects only one ear, most hearing aids with binaural capabilities can coordinate by replacing the muffled sound source with a clearer one coming from the unaffected ear.

Motion-sensor technology

Digital hearing aids work best when the wearer is stationary, which means that sound can become muffled while in motion. Some hearing aid models have attempted to correct this problem by communicating with the iPhone’s onboard motion-sensor. This feature is relatively new and is not available on most hearing aids, but those who have it can enjoy improved audio quality while walking or exercising. With the help of a Bluetooth connection, these hearing aids receive information from your iPhone about your position and constantly reevaluate the environment to maintain stability. Speech from the sides and back is emphasized without reducing the volume of important sounds like sirens and oncoming traffic. Eliminating the need to worry about audio quality while on-the-go is just one more way modern hearing aids make hearing enhancement safe, automatic, and comfortable.

T-Coils and loop systems

Hear the sound wave

The telecoil (T-coil) is a receiver built into many hearing aids that allows you to pick up sound coming from the telephone, television, stereo, and similar audio sources more clearly. It also reduces the likelihood of whistling when using the phone or near other electronic devices.

Recently, the functionality of the telecoil has expanded to allow users to tap into commercial loop systems that stream audio directly to their hearing aids in public spaces, such as movie theaters, concert halls, and places of worship. These FM and infrared loop systems enable users to hear sound from a microphone directly via a magnetic signal, rather than through the hearing aids’ microphones alone. Traditionally, loop systems broadcast sound through an assistive listening device, which was usually worn on a loop around your neck that sent audio into your hearing aids via the T-coil.

Today, hearing aid wearers no longer have to worry about carrying around a bulky device in public to hear the sounds they want. Most modern venues have installed induction loop systems that direct sound from a microphone through amplifiers, the signal of which is picked up through a loop of wire around a given space. This creates a magnetic field that can be detected by your hearing aids with the help of a T-coil. This feature, which is now common on most hearing aids, allows users to tune into these systems by simply switching settings to “T” while in the presence of a loop. The T-coil picks up the resulting fluctuations in the magnetic field and delivers the sound, which is pure and undistorted, directly into your hearing aids without the need for an external assistant listening device.

Induction loop systems are common in Europe but less widely available in the United States. Fortunately, government regulations have been put in place to assist those with hearing loss by providing mandatory disability services, such as closed captions and loop systems, in public venues. A list of locations that have had induction loops installed can be found at: http://www.aldlocator.com.

Bluetooth and wireless capability

Nearly every electronic device today makes use of Bluetooth technology in some way. By connecting and exchanging information between devices like mobile phones and laptops over a secure short-range radio frequency, this incredible breakthrough has completely changed how we think about communication. Hands-free connectivity is a huge benefit of Bluetooth, as it enables users to talk on the phone more safely while driving and connect laptops to available networks or hotspots when traveling.

While hearing aids used to require the use of wires or cables to connect, the advent of Bluetooth-compatible hearing aids offers a far more flexible wireless option. Almost all digital hearing aids now come equipped with the ability to utilize Bluetooth technology. You can pair your hearing aids to multiple devices, such as smartphones and laptops, to stream selected audio right into your ears. Typically, this is done with the use of a separate remote that can communicate with compatible devices. For those who are more tech-savvy, this remote can be substituted for a free Android™ or iPhone app that allows for multi-channel synchronization and manual adjustment of settings.

As of this writing, only a handful of hearing aid models are sold with the label Made for iPhone, which indicates that the device is compatible with most Apple and iOS devices. In the future, it is likely that all hearing aids will be able to connect to smartphones with a wide range of hearing-related features. Be sure to ask your hearing care professional about what’s available within your budget so you can make the most of your improved hearing experience.

Tinnitus treatment

Black man keeps his ears shut

More than 50 million Americans report some long-lasting ringing in their ears as a result of prolonged noise exposure or another auditory condition. When damage occurs in the nerve cells or cochlea, these areas can have difficulty transmitting auditory signals to the brain. In some instances, the brain overcompensates for this sudden absence of electrical impulses by becoming hyperactive, producing a sound that is not present in the external environment. This condition, known as tinnitus, is similar to the feeling of a phantom limb that is often described by recent amputees.

Sound generators and other tools to fight tinnitus are now available on many hearing aids. By determining the pitch and quality of your tinnitus, a hearing care professional can provide a backing sound that masks or otherwise reduces the severity of the internal noise. The newest technology analyzes the frequencies of incoming sound, allowing the digitized output to remove tones that approach the levels of the tinnitus sound. This approach, known as notch therapy, is only available in certain hearing aids but has been shown to drastically improve symptoms of tonal tinnitus (the kind where you hear a hissing, ringing, roaring, or similar sound). Talk to your hearing care professional to determine if a hearing aid with tinnitus notch therapy is right for you, and to see what other options are available to reduce the ringing in your ears.

Talk to a hearing care professional about your options

As you can see, hearing aids are available with a wide array of features. Schedule an appointment online with a hearing care professional to see what choices are best for you.