Need a hearing aid but don’t want the hassle or fashion nightmare your grandmother used to wear? Not a problem. Hearing aid manufacturers hear you loud and clear and have made great strides in the last few years to address what was wrong with Grandma’s hearing aid. Consequently, a growing trend in the hearing health field is the return to popularity of behind-the-ear (BTE) hearing instruments.
First manufactured and popularized in the 1950s, BTEs enjoyed a modest 25 percent market share until the 1970s, when custom in-the-ear (ITE) hearing aids became the rage. Through the 1980s and 90s, BTE fittings consistently accounted for about 15 percent of the market share. Hearing Review reported in 2006 that BTEs have recently gained the lead over other styles, constituting 44 percent of hearing aids fitted, while custom styles lagged behind (ITEs at 31 percent; in-the-canal [ITC] at 15 percent; and completely-in-the-canal [CIC] at 11 percent). Analysts attribute the BTE resurgence to a number of factors including new open-fit systems, receiver-in-the-ear options, directional microphones, wireless technology and improved cosmetics with sporty slim-line designs and colors. These factors, coupled with a lower repair rate for BTEs, in comparison to custom fitted hearing aids (ITE, ITC, and CIC), suggest that BTEs’ upswing is likely to continue in the near future.
Open-fit Systems
Two of the most common complaints from hearing aid users are related to occlusion and feedback. Hearing your voice as hollow or boomy, as if you were in a tunnel, is what is known as the occlusion effect. It is caused by the ear canal being blocked, or occluded, by an earmold or a hearing aid shell, both of which seal the ear canal, trapping air inside and increasing sound pressure. The sound of your voice causes the trapped air particles to move or vibrate like a drum, resulting in speech sounding louder to you. The tighter the seal, the louder the sound seems.
On the flipside, feedback is the whistling sound that occurs when an earmold or earshell is not sealed tightly enough. Amplified sound slips back through to re-enter the microphone of the hearing aid, resulting in a squeal similar to that of a sound system when someone comes too close to a microphone. Traditional venting, which can decrease occlusion, actually increases the likelihood of feedback.
New open-fit systems couple venting systems designed to guard against feedback with digital signal processing strategies that “sense” and reduce the opportunity for feedback before it occurs. Open-fit systems have a smaller opening on the outside of the mold than the one on the inside, allowing it to “collect” the trapped air and funnel it out of the ear.
These systems are ideal for people whose hearing is near normal in the low frequencies but slopes steeply in the high frequencies – a typical pattern for baby boomers with hearing loss caused by the natural aging process and noise exposure. A 2006 study comparing three types of open-canal hearing aids concluded that open-fit systems are an effective means of overcoming occlusion, one of the major barriers to people using hearing aids. Many hearing aid manufacturers currently offer open-fit BTE models.
Receiver-in-the-ear Technology
Another innovation aimed at reducing occlusion and feedback is receiver-in-the-ear (RITE) technology. The occlusion effect is reduced or eliminated by using deeply fitting hearing aids or earmolds (with no vents) that make full contact with the bony structure of the ear canal. This method minimizes the amount of air in the system and likewise the vibration of trapped air particles. The hearing aid receiver is mounted in the ear canal and the other components (microphone, amplifier, power supply) are housed in the BTE unit. Separation of the microphone and receiver effectively reduces the opportunity for feedback.
Hearing aids using RITE technology are ideal for people with moderately severe, severe or profound hearing losses. The number of manufacturers developing BTE units with RITE technology is steadily increasing. Together, open-fit and RITE BTE hearing aids account for about 30 percent of BTE hearing aid fittings.
Directional Microphones
By amplifying the noise of interest (the speech signal) over background noise, the directional microphone is the only hearing aid feature that has been shown to improve the signal/noise ratio to facilitate understanding of speech in noisy situations. Although directional microphones have been around for many years, the advent of advanced digital signal processing has catapulted directional microphone technology to a new level of sophistication.
Currently, directional microphone technologies include adaptive directional systems, automatic mode switching and multiband directionality. Adaptive directional microphones “decide” where the background noise is coming from (the side or the rear) and adjust accordingly. Automatic mode-switching directional microphones go one step further and “decide” when a directional microphone is needed. Multiband directionality systems take it to another level by “deciding” how the noise is distributed across the frequency range and automatically adjusting the frequency band as needed. All of these functions are achieved by complicated algorithms, making this generation of hearing aids truly smarter than the last. And people are taking note. The use of directional microphones has steadily increased in recent years. In 2001, less than 25 percent of hearing aids sold had some type of directional microphone system. Whereas in 2005, more than 35 percent of dispensed hearing aids had directional microphones and the greater increase of availability of the technology was seen in use by BTE instruments – 47 percent utilized this technology, in comparison to less than 20 percent of custom ITE instruments, according to Hearing Review.
Wireless Technology
Over the past 10 years, wireless communication systems have grown exponentially. Wireless communication options for people with hearing loss include induction loop, frequency modulation (FM) and Bluetooth applications, many of which work only with BTE hearing aids.
Induction loop technology utilizes a magnetic field as a transmitter and a telecoil (T-coil) of a hearing aid as the receiver. The T-coil accesses the signal of interest, such as a landline telephone, cell phone, television, voice microphone or any other signal transmitted via an induction loop. The crisp sound that seems as though it’s being pumped directly into the listener’s head can be a religious experience for first time users (see “UK and USA: Worlds Apart for People with Hearing Loss,” p. 26).
The good news about T-coils is spreading fast. Consumer purchases of hearing aids with T-coils increased from 39 percent in 2005 to 45 percent in 2006. Currently, more than 58 percent of all BTE instruments include a T-coil.
The wireless use of FM technology to transmit a signal from the speaker to the listener has been around for a long time; however, use of ear-level FM systems has exploded with the introduction of the Phonak MicroLink system in 1996. A small “boot” plugs into the BTE, picks up FM signals and pumps them directly into the hearing aid. Prior to the BTE boot, the only type of FM system available was an impractical style that had to be worn on a person’s torso – limiting it to primarily classroom settings. Current ear-level FM technology, limited to use with BTE instruments and implant sound processors, has helped fuel the growth spurt in BTE sales.
Bluetooth, the wireless newcomer, connects BTE users to direct input from cell phones, MP3 players, computers and other sound sources.
And finally, there’s a new and exciting development for people who wear hearing aids on both ears (binaural hearing aid users). Hearing Review reports that binaural fittings have been on the rise for some time. With new digital signal processing binaural communication strategies, binaural fittings could go off the charts! Manufacturers have developed ways for both hearing aids to communicate with each other to synchronize adjustments such as volume, compression, microphone directions and other features. See “Showstoppers” (p. 48) for more on new wireless binaural communication technology applications that made their debut at this year’s convention of the American Academy of Audiology.
Improved Cosmetics
And lastly, let us not forget that “all is vanity.” Hearing aid manufacturers have been anticipating an increase in consumers as the baby boomer generation ages. In addition, the success of early hearing detection and intervention has increased baby, toddler and children consumer populations. To satisfy tastes and needs of the young and not-so-young, manufacturers have been busy designing BTE hearing aids customized to consumer groups. Good-bye glum, bubble-gum beige hearing instruments; hello rainbow of color. Along with the dye job, BTEs have gone in for a face lift and tummy tuck resulting in more cosmetically appealing, slimmer, sleeker cases (see “Tuning into the Heart of Rock and Roll,” p. 38). With these new colors and shapes, attempting to hide hearing aids is so “last year.” Suddenly, ear gear is in and invisible is out! Besides, these days everybody is sporting something in their ear – iPod earbuds, Bluetooth earphones, and yes, sleek and savvy slim-tube BTEs.
BTEs are back and have brought with them a host of new features that are making consumers happy to see them again.
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