The traditional, the novel, and the choosing between them for your patients
The world is full of connectivity—cell phones, land-line phones, and television media—and people now expect to have access to communication devices. All technology to connect hearing aid users to listening devices in the world around them has one major functional goal: to make the signal of interest louder or easier to discriminate in the midst of background noise.
While telecoils and amplified TV and phone systems are not new to the hearing instrument marketplace, hearing instrument digital wireless technology has been available only for the last several years. The main technological difference between wireless and older technologies is that wireless technology functions on a digital protocol, whereas telecoils and older systems are based on analog transmission. Advantages afforded by digital wireless technology over analog include a more robust signal, the possibility to transmit binaurally in stereo, a more favorable signal-to-noise ratio (SNR), and the potential of encoding the signal for privacy concerns.1
Market research among hearing care professionals and hearing instrument users, conducted in the United States, France, and Germany by an independent market research firm, revealed clear advantages to being able to connect to audio sources with hearing devices. In particular, responses indicated the most desirable improvements to increase the market penetration of wireless-enabled hearing instruments were for television and cell phone usage.1
There are a great number of solutions available today for improving satisfaction while using the television and phone, both with and without hearing aids. These solutions vary in their applicability for the individual patient, so it is necessary to explore the user’s needs when choosing among them.
Traditional Solutions for Television Use
In the past, there were limited technological solutions for better hearing while watching television. The earliest solution for increasing the television volume was to turn up the volume dial or to sit close to the speaker. The main problem with this solution is that turning up the volume to a comfortable level for an individual with significant hearing loss often results in others in the room hearing the television at an uncomfortable level.
In addition, there is no specificity with regard to frequency response when the volume is increased in this manner. Thus, a person with high-frequency hearing loss might need to turn up the volume to a very high level to hear soft dialogue in the midst of music playing at the same time, but other sounds, such as a door slamming on the program, might also be amplified to an uncomfortable level for the listener.
Closed captioning for television programming is available typically by activating the option on the user’s television system. Originally designed to assist people with hearing loss, closed captioning typically contains spoken dialogue as well as non-speech information (eg, the tone of voice used, music, or sound effects). Closed captioning became a standard feature of television sets sold in the United States in the 1990s.2 Open captioning is the same as closed captioning; however, it is automatically embedded in the program without activating a special menu option as in the case of closed captioning. Open captioning is used in some theaters to make movie-going a more attractive option for people with hearing loss.
Wireless options for amplifying the television with or without the concurrent use of hearing aids are not new. One of these options is a listening system or personal sound amplifier, such as the TV Ears™ (www.tvears.com). These systems allow for the volume to be set individually for the person with hearing loss, without disturbing others in the room. Transmission of the sound occurs usually through infrared technology. Some systems will notify the listener when the telephone rings. In some cases, the amplified sound delivered to each ear can be individually set to accommodate for asymmetric hearing loss or loudness preferences. The individual typically wears a headset that is connected to the television wirelessly, or a neck loop that can transmit the signal directly to the user’s telecoils. Some hearing instrument models, like completely-in-the-canal devices, may be used at the same time with the headsets, although wearing comfort or feedback may be a problem in some cases.
Television Solutions for Wireless Hearing Instrument Users
The wireless amplifier options above are successful in amplifying sounds overall, but are not designed to meet the precise needs of the listener like hearing instruments. They are not programmed for the individual; for example, there is no precise discrimination in these systems’ settings for a person with a flat moderate hearing loss compared to a mild sloping-to-severe loss. In this way, hearing aids are more personalized to the individual’s hearing needs.
For that reason alone, it is not hard to imagine why optimal television usage with hearing instruments was so desirable among market research participants. If the hearing instruments can transmit the television signal while also applying frequency- and ear-specific gain settings, the user can enjoy better hearing abilities. Further, if the television signal is transmitted directly to the hearing instruments, the user does not need to wear a gateway device or headset of any kind, allowing for better comfort and mobility.
Several systems on the market today combine near-field magnetic induction (NFMI) technology with radio frequency technology, such as Bluetooth. Bluetooth is used to send the signal from an adaptor that is connected to the television to a body-worn gateway device that converts the radio frequency signal to NFMI. This NFMI technology has a limited range, such that hearing instrument users fitted with NFMI-driven wireless connectivity need to be in proximity (within 3 feet) to the gateway device. Often this gateway device is worn around the neck on a lanyard. The implications for the hearing instrument user may vary, but for some it may prove to be an inconvenience.
Other systems on the market transmit radio frequency information directly from the adaptor to the hearing instrument using a proprietary transmission protocol in either the 900 MHz or 2.4 GHz frequency band instead of Bluetooth. In terms of phone and television wireless transmission, both allow the user to be as far as 20 feet away from the adaptor. This lends greater convenience to the hearing instrument user. For example, when watching television, the adaptor can be mounted or placed next to the entertainment system, and there is no need for an additional gateway device to be worn around the hearing instrument user’s neck.
Adaptors and/or gateway devices that connect the hearing instruments to the television or another audio source, such as a stereo or computer, are typically dispensed along with the hearing instruments and paired either at the hearing care professional’s office or by the user at home. Wired connections, typically via RCA cables, are used between the adaptor and the television, but the connections to the hearing aids are wireless. A wireless remote control or the push-button on the hearing instruments can activate the wireless transmission and make volume changes. Figure 1 shows the wired and wireless connections in the ReSound Unite TV system, used with ReSound Alera hearing instruments.
With either an NFMI or direct wireless system, it is possible for both the hearing instrument microphone and the television signal to be simultaneously active. This provides the user with environmental sound awareness as well as an amplified audio signal, which is especially desirable when the user is watching television with others in the room and would like to participate in their conversations or comments during the program.
One of the considerations when transmitting audio information wirelessly to hearing aids is the delay introduced by the processing of the signal from the adaptor to the hearing instruments. This delay can be detrimental to sound quality, especially when the microphone is active (for environmental sound awareness) or in an open fitting. This is because direct sound from the television may mix with the wirelessly transmitted sound and a difference in sound quality can be perceived.
Delays longer than 30 ms can be perceived as echoes by the listener. In addition, delays in wireless transmission longer than 80 ms can contribute to a “lip-sync” effect, where the speaker’s lips on the television program do not seem synchronized with the speech transmitted to the hearing instrument user.1 Interestingly, minimal delays (shorter than 30 ms) actually can be beneficial for speech perception, since minimal echoes that are relatively the same level as the direct sound are integrated by the auditory system to resemble the sum of both signal powers.3-5 Among today’s current wireless offerings for television signal transmission to the hearing instruments, delays range from under 20 ms to 70 ms. For example, the delay with the ReSound Unite TV system is 18 ms.
The advantages of programmable wireless transmission to hearing aids are many. First, better SNRs can be achieved for listening to the television in a noisy environment. Because the hearing aids are programmed individually for the user, the television signal is amplified according to the listener’s hearing loss for each ear. Users can choose to have their wireless program set up to amplify only the transmitted sound from the television or a combination of the transmitted sound and environmental sounds.
Some systems, such as the ReSound Alera Unite TV system, allow for any number of hearing instruments to be paired to the same television through one adaptor. This allows multiple hearing instrument wearers in the same household to enjoy wireless connection to the television simultaneously without each having to have their own adaptors. The ReSound system also allows one set of hearing instruments to be paired to up to three different Unite TV adaptors, adding convenience for users with more than one television in different parts of their homes.
Finally, the hearing instrument user has control over the volume in several ways:
- Through the television set or remote control,
- Through the adaptor, or
- Through the hearing aid volume control (either on the hearing aids or through use of a wireless remote control paired to the hearing aids).
Each of these advantages contributes to better personalization of the signal amplification, which may result in greater satisfaction among hearing instrument users when watching television.
Traditional Solutions for Phone Use
Similar to the television solutions above, there are older, non-wireless as well as wireless solutions for better hearing on the phone. Some methods are contingent on features available on the hearing instruments, whereas others do not require hearing instruments to be worn.
Most phones have a speaker option, where the conversation can be routed not through the phone receiver but through a speaker on the base of the land-line phone or in some location on a mobile phone. Speaker phones can often be adjusted to higher volumes. However, the privacy of the conversation is threatened, as anyone within earshot can also hear the entire phone conversation.
Another option is to use an amplified land-line or mobile phone. This assistive listening device can achieve greater loudness levels in the receiver than a regular phone. Privacy is improved over a speaker phone option. However, much like the amplified listening devices available for televisions, the amplification is not specific or personalized to the listener’s hearing loss for each ear.
A TTY, or text telephone, is a device that allows people with hearing or speech difficulties to type messages to one another as an alternative to speaking and listening. A TTY is required for both parties to conduct a conversation. If one of the conversation partners does not have a TTY, he or she can use the Telecommunications Relay Service (TRS) and speak to an operator who will transcribe spoken words into text for the other partner. Conversely, the TRS operator will read aloud what that partner has written to the partner who does not have a TTY.6
A current solution akin to the TTY is the use of text messaging between mobile phone users. With virtually any mobile phone and service provider, text can be typed and transmitted in the same way as a mobile phone conversation between communication partners. This allows for all users, including those with hearing loss, to communicate on mobile phones. However, a significant drawback for using texting—through either a TTY, TRS, or mobile phone—is that it is difficult to have an involved or lengthy conversation. Further, speech tonality and inflection is lost, which can lead to miscommunication (eg, when sarcasm is used). In addition, users with manual dexterity or vision problems may have difficulty typing on the small keyboard or reading the small screen of the mobile phone.
A solution that directly involves the hearing instrument is the telecoil. Telecoils have been integrated into hearing instrument technology for many years, and work through induction from a magnet in the phone receiver. To use a telecoil, the listener must activate either a switch or a specific program in the hearing instrument. Once the hearing instrument is set to the telecoil mode, the phone can be held to the ear without feedback since the amplification is not occurring in the usual manner but rather through the inductive coil in the hearing instrument. Telecoils can also be used to achieve a better SNR in public areas such as theaters that are equipped with looping technology, lending them functionality outside of phone usage.
However, a significant drawback is that telecoils are optimized for use with land-line phones and may not be as effective with mobile phones. Further, the optimal position to hold the phone receiver to the ear with the hearing instrument in telecoil mode may vary per phone and per user, and there is often a learning curve associated with obtaining the best signal from the phone. Finally, the user must remember to quickly change to the telecoil mode or program on the hearing instrument when the phone rings, unless the hearing instrument is equipped with an “Autophone” feature. Autophone, sometimes with the addition of an adhesive magnet applied to the phone receiver to strengthen the inductive signal, automatically switches the hearing instrument to the telecoil program when the phone is brought to the ear. Autophone can also be used for an acoustic telephone program in some hearing instruments that do not have telecoils.
All of the above solutions will help to amplify the phone signal, and in the case of the telecoil and Autophone features, there will be specificity in the frequency response that can be programmed for the individual user. However, the phone signal will still only be presented monaurally. It would be optimal to provide the signal to both ears simultaneously, since improved speech recognition has been noted to occur when listening binaurally versus monaurally for listeners with hearing loss.8
Phone Solutions for Wireless Hearing Instrument Users
Cell phone connectivity was the second most desired improvement in terms of wireless features revealed by the market research. The need for more robust solutions arises in part from the high level of difficulty people with hearing loss have with using a phone. With phone conversations, there are no visual cues to permit speech reading, and often the connection is not perfectly clear. Further, some hearing instruments experience feedback whistling when an object such as a phone is held close to the ear. Even with well-fitted hearing instruments, it is no surprise that telephone use is a common concern among users. And when hearing instrument users complain of their troubles on the phone to others, it can lead to individuals not purchasing much-needed hearing instruments due to their anticipation of these problems with the phone.7
Regardless of the wireless transmission technology (NFMI or direct) employed by a hearing instrument, mobile phone solutions are all achieved through Bluetooth technology and an adaptor. Figure 2 shows the direct proprietary 2.4 GHz wireless technology used by the ReSound Unite Phone Clip accessory, which connects to ReSound Alera hearing instruments. The phone conversation is transmitted through the adaptor to the hearing instruments, and the user speaks into a microphone on the adaptor instead of on the phone. For this reason, the adaptor is typically positioned near the user’s mouth, by either clipping it to clothing, wearing it around the neck, holding it in the hand, or affixing it to the car visor while driving. With small adaptors, such as the ReSound Unite Phone Clip, that are dedicated to phone use, wearing comfort is unlikely to cause a problem; for multipurpose wireless devices that have more components for additional functionality and larger antennae, the adaptor may be larger and less comfortable to wear.
Wireless transmission of the phone conversation allows the user to have a greater degree of mobility, flexibility, and control. For some wireless transmission systems, such as ReSound’s 2.4 GHz system, the telephone can be as much as 30 feet away from the listener. Further, the volume can be adjusted through either the phone, the adaptor, a remote control, or the hearing instruments, for each or both ears. Since the signal is transmitted to both ears simultaneously, binaural listening on the phone is made possible without the use of a headset. This is especially important when the user is in noisy environments, and since hearing aid users have been shown to understand more of the telephone conversation when listening with two ears instead of one.9
For land-line phones, wireless transmission to hearing aids is also a possibility, as long as the land-line phone is Bluetooth-enabled. Another method of wirelessly transmitting land-line phone signals to the hearing instruments is the JK Audio Inline Patch (www.jkaudio.com/inline-patch.htm). The Inline Patch allows for wireless streaming to the hearing instruments via the same adaptor used for the television. With the ReSound Unite TV, RCA cables are connected to the Inline Patch and the sound is transmitted directly to the hearing instruments. Since there is no microphone on the Inline Patch, the mouthpiece of the phone can be held close to the user’s mouth, or the user can wear a headset with a microphone attached and the earphone portion placed behind the user’s ears and hearing instruments.
Today, users with hearing loss have more solutions from which to choose than ever before. Compared to most traditional solutions, wireless technology with hearing instruments provides greater benefits in terms of patient wearing comfort, range/mobility, binaural listening, and improved privacy. However, as with all clinical amplification decisions, the patient’s lifestyle and needs are of utmost importance when deciding which solution is the best. Matching the individual patient to the optimal solution can result in the greatest level of satisfaction possible.
- Groth J, Anthonsen F. Fewer wires, less complexity, and more connections: the new challenge for wireless hearing instruments, Hearing Review. 2010;17(6):28-30.
- Wikipedia. Closed captioning. Available at: en.wikipedia.org/w/index.php?title=Closed_captioning&oldid=434913022. Accessed June 21, 2011.
- Haas H. The influence of a single echo on the audibility of speech. J Audio Eng Soc. 1972;20:146-159.
- Lochner JPA, Berger JF. The influence of reflections on auditorium acoustics. J Sound Vibrations. 1964;1:426-454.
- Nabelek AK, Robinette L. Influence of the precedence effect on word identification by normally hearing and hearing-impaired subjects. J Acoust Soc Am. 1978;63:187-194.
- AboutTTY.com. What is a TTY? Available at: www.abouttty.com. Accessed June 21, 2011.
- Kochkin S. MarkeTrak VII: Obstacles to adult non-user adoption of hearing aids. Hear Jour. 2007;60(4):24-51.
- Nabelek AK, Pickett JK. Monaural and binaural speech perception through hearing aids under noise and reverberation with normal and hearing-impaired listeners. J Speech Hear Res. 1974;17:724-739.
- Picou E, Ricketts T. Comparison of hearing aid-based telephone routing strategies. Seminar presented at: American Academy of Audiology; April 2010; San Diego.
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