Forum Proceedings

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

1. Needs (unmet customer needs)

• Need to improve ability to hear speech in noise (hearing aid user participating in the Forum could not hear across the lunch table).
• Need to improve ability to hear non-speech sounds in noise (e.g. ability to hear a flute in an orchestral piece).
• Need to improve ability to hear speech at a distance (e.g. listening to a person some distance away is a problem even in a quiet environment).
• Need hearing technologies to incorporate wireless standards.
• Need microphones to have good directional performance at low frequencies.
• Need adaptive microphones (e.g. self-orienting, track speakers, switch speakers) for small group (e.g. business meetings) and classroom situations.
• Need hearing aid microphones with better directionality so the user can focus (their hearing) on the person they are listening to.
• Need hearing aid microphones whose directionality (e.g. directional, omni-directional) can be changed for different environments.
• Need hearing aid microphones whose directionality is easy for the user to control.
• Need a quick and easy means for hearing aid users to switch their microphones between omni-directional and directional modes (e.g. a hearing aid user can miss the beginning of conversations when they can't switch from omni-directional to directional mode quickly enough).
• Need lower "self-noise" (e.g. amplified noise of rustling clothes) for persons with mild hearing losses.
• Need binaural hearing aids.
• Need improved cosmetics for body worn microphones (e.g. look like jewelry, part of clothing or eyeglasses - does not look unnatural).
• Need microphones (e.g. body worn, desk top) that can lock onto and track sound source (e.g. speaker).
• Need body worn microphones (e.g. body worn microphone arrays) to look "cool."
• Need system for small group communication (people engaged in natural conversation - table of eight in a restaurant, business meeting, etc.).
• Need system for small group communication that does not require a microphone to be passed about.
• Need microphones (in hearing aids, in personal FM systems, etc.) that can "pick up" and orient toward new speakers engaged in natural conversation (e.g. small groups conversation at the dinner table or at a cocktail party).
• Need improved microphone positioning (relative to speaker or speakers mouth) to ensure good sound pickup.
• Need reimbursement policy to support the purchase of advanced hearing aid technology (for persons with all degrees of hearing disability).
• Need to educate persons with hearing disabilities on the benefits of hearing aids and assistive listening systems (e.g. only 20% of people who should use hearing aids are actually using hearing aids).
• Need improved hearing evaluation and hearing aid fitting.
• Need standard procedures/tests for evaluating all microphones in order to compare their performance.
• Need education on different microphones and listening systems and how each are suitable for different applications and sound environments
• Need to better educate consumers, middlemen, audiologists, and manufacturers about microphones (types, uses, applications, etc.) used in hearing aids, ALS, etc.
• Need to better educate consumers about the performance/possible problems of microphones in hearing aids, assistive listening systems, etc.

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

• Microphones (generally) have fixed performance characteristics that are not suitable for all environments and activities.
• Omni-directional microphones - receive sound equally from all directions.
• Directional microphones (all sorts) emphasize sound from the direction they are being "pointed."
• All directional microphones make the user seem closer to the sound source than he or she really is - "reduce the acoustic distance."
• Directional microphones include "cardioid family" microphones and beam forming microphone arrays.
• Directivity index is a measure of how directional a microphone is. Consider a cardioid microphone with a directivity index of 4.7 dB. If we spoke into this microphone at a distance of 5 feet in a reverberant environment, a directivity index of 25dB is needed in order to "sound" as if we were 1 foot away from the same microphone.
• While many microphones are available having a wide range of directional responses - not all are appropriate for hearing technology because of size, cost, power consumption, processing requirements, etc.
• Noise is not equal. Noise from speech babble is worse than machine hum.
• Most noise reduction techniques work well only for environments with few or stationary (unchanging) noise sources.
• Persons with hearing impairments often must "cuddle up" to the speaker in order to communicate.
• Higher reimbursement rates are now directed toward hearing technology for persons with severe hearing disabilities - a small market segment.
• As long as the hearing aid market remains small, research and development costs will remain a barrier.

Beam forming microphones

• Directional microphones (e.g. some body worn beam forming microphone arrays) can currently achieve directivity index of 12 dB.
• Beam forming microphone arrays are now used in hearing aids, hand-held batons, body worn, eyeglasses, table top, etc.
• Adaptive beam forming microphones arrays (desktop, wearable) automatically change their directional response (e.g. alter directivity with changes in environmental noise, track speaker, switch to a new speaker).
• Beam forming microphone array has been placed on an eyeglass frame (NIH sponsored research with four microphones on the frame).
• Microphone technology will be increasingly dependent upon digital signal processing.
• Wyn Suede carried out important research on beam forming microphones.

Hearing aids

• Hearing aids microphones (generally) have poor directional performance at low frequencies because of the small separation between hearing aid microphones.
• Directional hearing aids - must face the speaker (sound source). Decreased ability to locate new speakers (sound sources).
• Directional hearing aids sometimes have a single microphone with two "ports."
• Directional hearing aids with two microphones and digital signal processing (beam forming) - provide limited improvement (reduce background noise less than 5 dB).
• Directional hearing aids have an effective hearing range of six feet or less.
• Some hearing aids can be manually switched between directional and omni-directional modes.
• Some hearing aids automatically switch between directional and omni-directional modes in response to the environment (more convenient than manual).
• Some hearing aids have dual microphones - directional response is obtained with beam forming techniques.
• Some hearing aids (ITE, BTE) with dual microphones (beam forming) can be switched between cardioid to hyper-cardiod beam patterns.
• Hearing aids generally use 1.1volt zinc-air batteries.
• Battery state-of-the-art is much more advanced than the battery technology employed in hearing aids.

Binaural hearing aids

• Of persons wearing hearing aids, 53-56% have two aids (Hearing Journal cited).
• CRoS hearing aids (a hearing aid with a microphone on opposite side of persons head) are useful when riding in a car.
• BiCRoS hearing aids could be adapted to do binaural processing.
• CRoS hearing aids with additional microphones are being looked at.
• Binaural hearing aids have been attempted. Two hearing aids hard-wired to an external digital signal-processing unit (a prototype device). Two hearing aids linked by an AM wireless link (Telex product no longer on market).
• Early binaural hearing aids (wired and wireless) were oversimplified.

System for Small Group Communication

• Systems for small group communication require that the microphone be passed around (single-microphone system) OR that everyone has their own microphone (multi-microphone system).
• Systems that provide poor sound quality to the listener are worse than having no system at all.
• People are intimidated (uncomfortable, unaccustomed to) speaking into microphones.  As a result they speak too loudly, too softly or position themselves too far or too close to the microphone.
• Sound amplification systems (e.g. public address systems in schools, trains, and airlines) often have poor sound quality and provide little benefit to hearing-impaired individuals.
• Sound amplification system performance (often) depends upon the user speaking directly into the microphone.
• Remote microphone - most commonly a microphone with an FM transmitter.
• Systems with a single microphone -cumbersome or impossible to pass a microphone from speaker to speaker.
• Systems with a single microphone -listeners miss the beginnings of conversation as the microphone is passed from speaker to speaker.
• Assistive listening systems (FM, infrared, inductive loop) often have multiple microphones connected to a single transmitter.
• Systems with multiple microphones are difficult to set up properly - cumbersome or impossible to place a microphone in front of each speaker.
• Systems with multiple microphones - difficult to identify and orient toward the current speaker.
• Multi-microphone systems have been built into rooms - with automatic switching (pick up new speaker) and mixing (get input from correct microphone). These systems have good reception and signal to noise performance (reference Shure's Intellimix).

Public policy

• ADA standards have not been established for many difficult hearing environments.

Related technology

• Parabolic microphones with humans to "aim" them constitute a highly directional microphone system.
• Personal Digital Assistant (PDA's) are sometimes used to beam text based communication to another person (e.g. friends communicating at bars).
• "Blue Tooth" - named after a King of Denmark who had blue teeth - is an international wireless communication standard being developed to support communications between electronic devices such as TV, cell phone, and computers.
• Microphones for cochlear implants with signal processing.
• Laser pointer microphone picks up whatever you are aiming at (20 degree azimuth).
• Baton microphones.
• Sound recording industry often employs several microphones (of various sorts) and brings sound signals together through a mixer.
• Remote microphones with FM transmitters are used in professional music and theater.
• Teleconferencing employs various types of microphones.

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3. Needed Technology (refinements, innovations)

• Natural hearing systems should be studied and modeled (e.g. a small bird in Australia is able to localize very low frequency-the acoustical path in its skull does something to create the delay)
• Microphones should be highly directional across all speech frequencies (200 Hz to 7 kHz).
• Microphones should have increased directionality (higher directivity index).
• Microphones should reduce "wind" and "outdoor" noise.
• Microphones should work in very complex acoustic environments where the sound sources (voices) may be physically moving about.
• Microphones should improve the speech in noise ratio.
• Microphones should have wide dynamic range.
• Microphones should have a linear response to sound signals over entire auditory frequency range.
• Microphones should provide hearing-at-a-distance (analogous to depth-of-focus for a light microscope) especially in difficult acoustic environments.
• Microphone sensitivity should adjust to the environment (high sensitivity for quiet conversations in quiet environments, lower sensitivity for loud conversations in noisy environments).
• High research and development costs for improved technologies.
• Cost (e.g., R&D, production, price reimbursement issues)
• Highly directional microphones (hearing aid, hand held or wearable) are hard to aim (e.g. locating a new speaker).

Beam forming microphones

• Beam forming microphone arrays (e.g. desktop microphones) should provide orientation cues (e.g.  N S E W lights on beam forming device - indicating direction of speaker).
• Beam forming microphone arrays (e.g. desktop microphones) should be adaptive (e.g. track moving speaker, pick out and orient toward new speaker, change directional performance in response to environmental cues).
• Adaptive filtering should identify and eliminate steady state noise such as wind noise and fan hum.
• Beam forming microphone arrays should be employed in hearing aids, "optional attachment around the ear," body wearable, hand held, and table top devices.
• Beam forming microphone arrays (with necessary processing) should be small and inexpensive.
• Beam forming microphone arrays should work in difficult listening environments (e.g. many sound sources, noise from all directions)
• Beam forming microphone arrays should work in real time (fast response, no processing delay).
• Beam forming microphone arrays (two or more microphones) should not generate more noise than single microphone (24 dB - 27 dB with a filter band up to 10 kHz).
• Beam forming microphone arrays directionality should adapt in response to environment factors (e.g. level, orientation and type of noise, multiple speakers, etc.)
• Beam forming microphone arrays should orient to new speakers or track moving speaker.
• Beam forming microphone arrays should sense noise from all sources and directions and change their performance based upon this information.
• Beam forming microphone arrays should pick up orienting cues. (Microphone anticipates who you want to hear, not who you are currently "pointing at.").
• Beam forming microphone arrays should have user selectable steering modes (user needs to know which modes will work in each environment)
• For persons with intact hearing, the brain automatically orients the eyes to the sound source.  For a adaptive microphone system (orienting to a sound source), the brain can't (directly) fulfill this function and the user may not be able to physically re-orient to new speakers fast enough.
• Beam forming microphone performance depends upon the placement and separation of the microphones.  The size and form of the hearing aid, hand held or body worn device will impact microphone performance.  Increased a devices size or changing its shape may not be acceptable to users.

Hearing aids

• Directional hearing aids (using two or more microphones) should employ improved digital signal processing schemes.
• Hearing aid microphone directionality should be user and/or automatically controlled.
• Directional hearing aids should have an improved user interface to control microphone directionality (e.g. omni-directional, directional or degree of directivity).
• Hearing aid microphones should be weather proof, durable, smaller, and less expensive.
• Hearing aid microphones should employ adaptable beam steering that fits the acoustic environment (e.g. kids sitting to the driver's right or in the back seat of a car)
• Hearing aids with improved microphone performance (e.g. advanced beam forming with powerful digital signal processing) should not increase power consumption (work with standard hearing aid batteries).
• Hearing aids should have higher gain settings without feedback (through hearing aid microphones).
• Hearing aid function should be "matched" to residual cochlear function.
• Remote microphones should have a wireless link directly to a hearing aid receiver.
• As hearing aid capabilities become more complex it may become more difficult to properly fit the hearing aid to the client.
• Hearing aid feedback is still a problem due to poor earmold fitting.
• Hearing aid feedback is still a problem because of the small physical separation between hearing aid speaker and microphone (e.g. for ITE aids).
• Tiny market for hearing aids.
• Adding hardware to increase processing power also increases power consumption and decreases battery life (or time-between-recharge).
• Increasing battery size (to provide additional power) is precluded for small hearing aids.

Binaural hearing aids

• BiCRoS hearing aids should perform true binaural processing.
• Binaural hearing aids should have a wireless bi-directional communication link.
• Binaural hearing aids should employ binaural processing (i.e. hardware/algorithms that take advantage of head-shadow effects, signal time delays, etc.).
• Binaural hearing aids should do beam forming with the microphones from both hearing aids (sound received at both hearing aids with wireless connection and true binaural processing).
• There is an incomplete understanding of how impaired ears function. For example, how do impaired ears process binaural cues?
• Research is needed on binaural "stereo sound" pickup and processing by persons with and without intact hearing.
• Binaural processing by the brain is not fully understood in intact hearing systems  (e.g. how is a voice picked out and focused upon at a cocktail party?).
• Binaural hearing aids may not be accepted if people perceive that their hearing is worse if they use two hearing aids.

Body worn microphones

• Wearable beam forming microphone arrays (e.g. microphones spread over surface of necklace or eyeglasses) should have a wireless link to the hearing aids.
• Wearable beam forming microphone arrays (e.g. microphones spread over surface of necklace or eyeglasses) should be adaptive (e.g. change directional performance in response to environmental cues).
• Body worn microphones (e.g. eyeglass microphone arrays, body worn microphones, etc) must have acceptable size, weight and appearance.
• Hand held or wearable beam forming microphones may not be accepted because of added expense, complexity (another thing to carry around) or appearance (odd looking).
• Hand held or wearable beam forming microphones may not be accepted if people perceive that their hearing is worse if they use additional devices.
• Hand held microphones with laser pointing might be socially unacceptable (annoy other persons).

Systems for small group communication

• Everyone should be able to communicate with a hearing aid user via common telecommunication devices (phones, pagers, etc.).
• Telecommunication devices (cell phones, pagers, etc.) should act as receivers and be interfaced to hearing aids via neck loops and DAI.
• Hearing aids should be equipped with a receiver (in-built or accessory) and receive wireless communication directly.
• Wireless communication devices that now support data communication (e.g. Palm Pilot) should incorporate microphones and support voice communication.
• New concept for assistive listening system - microphone transmitter broadcasts on some frequency; press "frequency select" button on cell phone (pager or similar device) to select among transmission frequencies; cell phone interfaced to hearing aids via neck loop, DAI or headphones.
• Systems for small group communication should provide orientation cues (e.g. N-S-E-W lights on beam forming device - indicating direction of speaker).
• In order for systems to work all hearing aid users must have appropriate receivers and all non-hearing impaired must have appropriate transmitters.
• Complex systems tend to be larger and may not be accepted by users (e.g. impede physical activities, poor aesthetics)
• Systems may not be socially acceptable.  How do friends, peers and coworkers view the person using the system?  Will people be willing to carry and use cell phones (related devices, remote microphones and transmitters, etc.) in order to communicate with persons with hearing impairments?
• Power consumption - adding a receiver and processing hardware to hearing aids increases power consumption and decreases battery life (or time between recharge).
• Systems that require additional hardware have increased associated costs.
• Classroom situations are complex.  It is currently not practical for each student and teacher to have a separate microphone.
• Complex systems (many components, wires, require careful setup, sensitive to environmental factors) are not accepted in many situations (e.g. classrooms, cocktail parties, etc).

Other Issues

• Worldwide performance standards should be established for hearing aids.
• Marketing should be employed to improve consumer awareness of advanced hearing technology.
• In-the-ear receiver that resembles accepted technology (e.g. like Back Street Boys' ear receivers).
• Designer colors for teenagers.
• It is not true Bell array built into ceiling, 1980's - complex mixer system - did not work.

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