Forum Proceedings

The following data was collected during the stakeholder forum and summarizes the comments of forum participants.

1. Priority Customer Needs

• Ease of use
• Need standardization so that receiver and transmitter match
• Need predictable level and quality of signal Need to be able to use in public areas like tour buses, museums, stadiums, crowds and churches
• Need training for users/operators of the transmitters
• Need to benefit people with any degree of hearing loss
• Need to be used in language translators, theatre, sporting events, classrooms, museums, tours

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2. State-of-the-Practice (current technology)

• FM systems are single speaker/single listener and single speaker/multi listener.
• No multi speaker/multi listener systems are available.
• Both transmitter and receiver can be mobile.
• Transmitter worn by speaker and speaker can move around.
• Transmitter/Microphone must be near the sound source (e.g. speaker's mouth).
• Personal FMs improves SNR and shortens acoustical pathway between speaker and listener).
• FMs are compatible with other devices (e.g. place transmitter microphone near TV or Radio)
• FMs does not require line of sight between transmitter and receiver (i.e. FM transmission is Omni-directional 360 degrees).
• Sound quality is dependent upon the frequency response of the transmitter microphone.
• FMs use frequency bands within the 72-76 MHz range and the 216 MHz-217 MHzfrequency range.
• FMs use "narrow band" (typically 50 KHz) or "wideband" (typically 150 or 200 KHz) transmission.
• It is often difficult for the user to select the correct frequency for FM systems having multiple frequency channels
• FMs are susceptible to interference from other FM radio sources (such as pagers and emergency vehicles) especially at lower (non-dedicated) frequencies (72-76MHz)
• FM systems can be used in most environments (e.g. classrooms, museums etc.).
• FM system can't be used in certain environments (e.g. industry, hospitals, airplanes where Personal FMs interferes with electronic equipment)
• Susceptible to electromagnetic field interference (e.g. lighting, motors, computers, lightning, power strips, etc.); The acoustic quality of narrow band transmission is typically not as good as the acoustic quality of wide band transmission.
• FMs are subject to signal drift (generally a low frequency system problem)
• For transmitters using low frequencies (72-76 MHz) narrow transmission bandwidth (10 KHz) limits signal quality and dynamic range. (e,g, limits sound quality)
• No guarantee that you are tuned in (e.g. FM receivers don't signal the user when the transmission carrier is lost or the carrier frequency band has been switched at the transmitter)
• FM systems provide a personal communication channel between the speaker and the listener.
• Concerns for privacy and security ( i.e. any receiver tuned to the transmitter frequency can "listen in." Also the FM signal can not be easily confined to the "room.")
• Small FM receiver is an accessory to some Hearing aids (e.g. FM boot)
• Small FM receiver is built into some BTE hearing aids
• Custom fit - mechanically and acoustically (e.g. Hearing aids response to a signal from the FM receiver is similar to the response directly from the hearing aid microphone.)
• FM receivers are cosmetically acceptable (Receiver is small and inconspicuous. Accepted by children in school environments)
• Effort to standardize different makes of Hearing Aids to accommodate modular FM receiver (FM boot).
• Some difficulty achieving full compatibility between standardized FM receivers and HA processing capabilities (which may differ across brands and models)
• FM transmitter too large (may interfere with vigorous physical activities like dancing, aerobics, etc)
• Receiver antenna is too long (strange looking on boot).
• Limited battery power (i.e. number of hours between charges).
• The FM (built in or boot) receiver does not require a separate power source (draws power from the battery hearing aids battery.)
• FM receiver decreases hearing aids battery life (i.e. time between replacements)
• Transmitter not powerful enough (range is limited)
• Battery life on transmitter is too short
• Increasing transmission power (range) decreases the time between charge.
• No low battery power indicator
• No automatic receiver on/off (e.g. power consumption continues when there is no carrier frequency detected)
• High system cost
• Transmitter and receiver easily lost. Small and delicate antenna
• Multi-path problems can cause drop out (e.g. building structural elements interfere with the direct transmission path. Transmission signal reaches the receiver by multiple paths and "sums" destructively.)
• FM-boot only fits on BTE
• General problem for smaller HA to accommodate FM receivers.

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3. Needed Technology (Innovations, Refinements)

• Ideal system should have a transmitter, a body‑worn repeater and a wireless link to a HA receiver
• Transmission protocol should not be limited to FM
• Should consider using universally accepted wireless standard (e.g. consider spread spectrum, ultra‑wide band, frequency coding phase shift keying, blue tooth.)
• Frequency agile (has capability to automatically "scan" and " lock onto" the carrier frequency)
• Supports bi-directional handshaking between receiver and transmitter.
• Handshaking might be all wireless or mixed (e.g. part wireless and part acoustic).
• Bi-directional handshaking might support channel switching, notification of poor signal reception, low battery indicator, etc.
• Guaranteed privacy and security
• Adjustable transmission range 0-40m indoors
• Improved Digital Signal Processing hardware and software is needed to support advanced communication protocols (e.g. spread spectrum)
• Clear transmission (i.e. good dynamic range, high signal to noise ratio, etc.)
• FM transmitter, microphone and receiver do not introduce unintended signal distortion(It should be noted that signal distortion is sometimes intentional - for example signal compression is sometimes built in at the transmitter.)
• Legislative action may be required for frequency spectrum allocation (i.e. the current allocation at 72-76 MHz may not be suitable for some advanced wireless communication protocols.)
• Transmitter should be size of fountain pen to size of cigarette pack
• Transmitter should weigh 4-5 ounces
• Backward compatible - works with existing hearing aids (e.g. a wireless communication accessory could replace the current FM-boot in a one to one fashion.)
• Handle both analog and digital.

a. Transmitter Controls

• Watertight (e.g. sealed membrane on/off switch)
• Larger (e.g. requires low precision)
• Tactile (e.g. switch location and function identifiable by touch.)
• Up/ Down switch to select transmission frequency.
• Stand-by feature (e.g. use input threshold detector to place transmitter on low ‑ power stand-by when the input signal is below a threshold. This may require signal processing to account for voice loudness and the varying sound environment.)
• Feedback to user when transmitter active (e.g. LED or blinking LED)
• Transmitter can be "plugged" into a wide array of consumer and telecom devices (telephone, alert systems, home environment, computers, mixers, etc.)

b. Transmitter Microphone

• Processing of microphone signal adapts in response to environmental variable (e.g. signal strength, environmental noise characteristics, reverberation)
• Water resistant, wind resistant (Disposable windscreen), shock resistant
• "Flexibility" (e.g. microphone can be detached from the transmitter)
• Ability to switch (swap transmitter microphones with differing functional characteristics.)
• Low sensitivity to vibration (does not pick up vibration noise)
• Minimal internal microphone noise
• Microphone and transmitter share same power source.
• Microphone located at one end of transmitter.
• Microphone should be highly directional and capable of picking up sound signal (voice) at 8 to 10 feet in a noisy environment.
• Microphone should have a directivity pattern of 20-40 degrees
• Size of microphone and transmitter should have a total size of 1" to length of pen.
• Microphone (even if swappable) and transmitter should form an integral unit
• Mute option, controlled at transmitter (i.e. transmission carrier maintained, but no sound signal transmitted)
• Microphone should be able to pick up speech in noise (Sensitivity without saturation)
• Microphone should be able to pick up speech in quiet (i.e. Sensitivity should allow microphone to pick up quiet voice in quiet environment.)
• Switch able between omni directional and directional microphone.
• Smart mike system should be considered (Multi-microphone array beam forming microphone that adapts to sound environment, locates and tracks sound sources.)
• Life of battery 15 to 20 hrs for the transmitter
• Power level indicator.

c. Transmitter Antenna

• Antenna inside transmitter, never breaks
• Omni directional transmission.
• Optional external antenna jack for 4" external antenna (increase transmission range)
• Replaceable
• Antenna can "fold out" from transmitter allowing transmitter to be "stood up" on table.

d. Body worn Repeater

• Work with or w/o hearing aids (can be interfaced with HA, used with headphones etc)
• Should have 3.5 mm jack (i.e. for D.A.I or inductive neck loop).
• Support wireless transmission to hearing aid. (i.e. F.M. or other wireless protocols).
• Repeater should accept wireless data i/p (non analog signals from computer, etc.)
• Repeater can interface to "other" electronic devices (e.g. tape recorders, public address systems, mixers etc.)
• Receive all available frequencies (Works across all allocated frequency ranges.)
• Tunable by user (user can select carrier frequency)
• Repeater should be able to communicate to the HA (e.g. T‑Coil, D.A.I, F.M ‑ boot).
• Repeater should be able to handshake bi‑directionally with any wireless transmitter.
• Should have user selectable volume Control
• Watertight (e.g. sealed membrane on/off switch)
• Batteries of the control should last 3-4 weeks at 8-10 hours of continuous use
• Repeater battery (rechargeable or disposable) should be recyclable.
• Disposable batteries should have 40 hrs life minimum.
• Battery level indicator
• Feedback to user on loss of transmitter signal.
• Display Transmitter Carrier Detection
• Repeater should have up/down switch, to select initial transmitter frequency
• When turned on receiver should select last transmitter frequency used when turned off.
• Size - 6"x3/o"x'/4"
• Same antenna characteristics as transmitter (e.g. omnidirectional transmission for handshaking, same range as transmitter)
• Repeater should have on/off indicator (e.g. LED)
• Adjustable according to individual requirements
• Active Tone Control, Active high frequency gain

e. Hearing Aid Receiver

• Ideally a wireless receiver should be built in to the (BTE) hearing aid.
• A receiver accessory to the HA (e.g. wireless or FM-boot ) is less optimal.
• Receiver should be durable (unbreakable)
• Cosmetically appealing with small size, small antenna and light weight
• Additional weight for receiver should be about the same as a current FM boot accessory
• Smart signal selection capabilities to pick up and lock on to the wireless signal from the repeater (e.g. strongest FM signal)
• Manual signal selection capabilities (e.g. user presses a push button to manually select and lock onto a signal in multi-channel environments such as theatres)
• Antenna should be inside receiver.
• Wireless receiver should be affordable
• Easy to use manual on/off switch
• For receiver boot accessory ‑ electronic interface to HA must be reliable (e.g. Durable, waterproof, etc)
• No visual indicator (e.g. power level, signal detect, etc) needed on HA
• Low battery indicator (e.g. beep, vibrate)
• BTE receiver should have wireless communication link with repeater.
• No bi-directional communication from HA receiver to repeater (e.g. to control or notify repeater)
• Moisture Resistant
• Wireless receiver powered off of HA battery.
• Receiver battery should source > 3-4 mA current.
• Receiver battery should be easily replaceable.
• Rechargeable BTE battery with life of 12 hrs per charge.
• Compatibility with existing BTE's (backward compatible)
• Explore new/ larger markets (e.g. communication between coach and players)

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4. Barriers (to realizing technology)

• Cost (hearing aid w/built‑in receiver are now $500-3000 dollars adding an FM or wireless receiver might raise HA cost to $3000-4000 dollars)
• Miniaturization (e.g. general problem for some wireless protocols such as spread spectrum which require significant electronics.)

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