Bluetooth Wireless Technology for Communication Access
Ingrid McBride, Au.D., CCC-A Clinical Associate Professor Arizona State University
THE GOAL: COMMUNICATION ACCESSIBILITY
Even with the arsenal of HA/CI technology available today, many people need alternative technologies to supplement the hearing aid or CI Consider problems of noise & reverberation Consider distance from sound source
Assistive Listening Devices
Improve SNR picking up the signal directly from or close to the sound source
Increases the loudness of specific sounds only Minimizes background noise Eliminates distance between the speaker and the listener Eliminates reverberation (echo)

TYPE OF ALDs

Principle of remote microphone placement or direct connection to the sound source is common to all types Difference between types is the means of signal transmission

Hardwired Wireless

Signal-to-noise ratio advantage

NOISE NOISE SPEECH NOISE

Speech

Speech Speech

Speech Speech Speech

Wireless Technology

FM Infrared Induction Loop Primary advantages Remote microphone placement or DAI connection transmits signals directly from the source to HA/CI Overcomes noise, distance, reverberation Increased signal-to-noise ratioup to 20 dB NO cords/wires between transmitter & receiver BUT still have cords between device and transmitter

Background

YET.there is minimal use of ALDs in the adult population

Possible Reasons Why

Ease of Use of Devices (Jerger et al, 1996) Cost of devices (Fabry et al, 2007) Lack of considerable counseling, instruction and coaching re: FM use

(Boothroyd, 2003)

Cosmetics and intrusiveness (Fabry et al, 2007) Lack of clear cut criteria for determining device candidacy (Fabry et al, 2007)
MarkeTrak VI Results (Kochkin, 2002)

User Satisfaction

Kochkin (2005) reported that hearing aid users rate the use of mobile phones in conjunction with their hearing aids as one of the top 3 most troubling situations they face, with only 59% of all users reporting acceptable conditions in this scenario.
ANSI C63.19 - standard for hearing instrument/cell phone compatibility
Feedback Noise Interference Lack of clarity and loudness
Ratings predict compatibility of a given hearing aid/cell phone combination
Installed base of BT devices

What is Bluetooth?

Radio-based technology that permits short-range wireless mobilitydigital FM Allows devices to communicate and transfer information wirelessly through personal area networks Cable Replacement Technology: Replaces cables connecting portable and/or fixed electronic devices Advantages Robustness Low power Low cost Security Portability Multiple users can be in the same room using BT
FM vs. Bluetooth Frequency Bands
Globally operates on the unlicensed, Industrial Scientific Medical (ISM), low power microwave band at 2.400 GHz 2.48 GHz.

Dedicated FM 216-217 MHz

Bluetooth Connectivity
Allows wireless connectivity and data/audio exchange between multiple Bluetooth-enabled devices Cell phones Telephones MP3 players PDAs Lap top computers/PCs Printers GPS receivers Digital cameras
Cars BT adapters for nonBT devices Video game consoles
Why is it called Bluetooth?
Named after the 10th Century Danish Viking king, Harald Bltand known for his unification of warring tribes from Denmark including Skne (present day Sweden) Bltand translated into English become Bluetooth Selected by Bluetooth developers originally as a code name for the project but it stuck as the official name Like its namesake, Bluetooth is intended to unify the many electronic devices marketed by the telecommunication and computing industries

Bluetooth Wireless Technology
Bluetooth technology can be uni-directional or bi-directional and does not require line-of-sight positioning of connected devices
Bluetooth wireless technology is able to penetrate solid objects
Communication between devices is direct Use limited to paired devices
Point-to-point technology

Bluetooth Relationships

A Bluetooth-enabled device can connect to other Bluetooth-enabled devices in proximity BT symbol verifies device is BT-enabled Any time a BT link is formed, it is within the context of a Personal Area Network (PAN) or Piconet.
Short range, ad hoc network
Piconets are established dynamically and automatically as BT-enabled devices enter and leave radio proximity
A Piconet consists of Master and Slave devices
One device functions as the master; devices connected to it function as slaves.
Master sets up and controls the communication between the two All traffic must pass through the master Slave receives incoming signals and sends responses back to the master
The Bluetooth network topology
Piconet ad hoc network group of up to 8 devices Data can be transferred between the master and one other device Devices can switch roles and the slave can become the master Scatternet 2 or more piconets connected together

Bluetooth Basics

Uses radio frequency technology called Frequency Hopping Spread Spectrum (FHSS)
Reduces interference between wireless technologies sharing the 2.4 GHz spectrum Ensures that large numbers of devices can coexist in a small area without the need for manual selection of frequency channels A physical radio channel is shared by a group of devices that are synchronized to a common clock and frequency hopping pattern
The signal hops among various frequencies within the band; combats interference and fading
Adaptive Frequency Hopping
Signal hops among 79 frequencies at 1 MHz intervals to give a high degree of interference immunity Within the spectrum, AFH takes advantage of the available frequency Detects other devices in the spectrum and avoids those frequencies AFH allows for more efficient transmission Operating frequency bands: 2 2.400 GHz 78 2.485 GHz

Bluetooth Compatibility

Devices you want to pair must be compatible Bluetooth Core Specification how the technology works (protocol architecture) Bluetooth Application Profiles to use Bluetooth technology, a device must be able to interpret certain Bluetooth protocols or rules; the profiles define the possible applications Passkeys supported
Bluetooth Core Specifications
Developed and licensed by the Bluetooth Special Interest Group (SIG) Early versions 1.0 and 1.0B Had many problems Bluetooth v1.1 Bluetooth v1.2 Backward-compatible Faster connection and discovery Adaptive frequency-hopping spread spectrum for less RF interference Higher transmission speeds-up to 721 kbits/s Extended Synchronous Connections (eSCO) for improved voice quality of audio links

Bluetooth Specifications

Bluetooth v2.0
Fully backward-compatible with 1.1 Introduced EDR-Enhanced Data Rate for 3 times faster data transfer (2.1 Mbit/s) Reduced complexity of multiple simultaneous connections due to additional bandwidth Lower power consumption through a reduced duty cycle
Bluetooth v2.1 + EDRmost recent July 07
Fully backward-compatible with 1.1 Increased strength of security Simpler pairing of devices Extended inquiry responsemore info during discovery to allow better filtering of devices before connection. Near Field Communication (NFC) cooperation If you have this, just by bringing 2 devices close to each other (a few centimeters), you create a connection e.g. bringing a mobile phone to a camera, uploads the photos from the phone to the camera.
Bluetooth Application Profiles
Device used must support the appropriate Bluetooth profile of the Bluetooth receiver Profiles indicate the range of applications of a device At least 33 different profiles exist HFP Hands-free Profile HSP Headset Profile (most common) Provides support for BT headsets to be used with cell phones Phone must support HFP or Headset HSP profile A2DP Advanced Audio Distribution Profile High-end audio profile with broader bandwidth and stereo capabilities Defines how high quality audio (stereo or mono) can be streamed Required to listen to music from an MP3 player

Bluetooth Communication

To work, devices must find each other before communication between them occurs Terminology is non-standardized; also known as: marrying, shaking, connecting, seeking, bonding, identifying, linking and accepting During a connection between BT devices, an exchange of unique BT identity (global ID) takes place Device name (48-bit address) Device class List of services or profiles

Bluetooth Pairing

Getting two Bluetooth devices to communicate is a three-step procedure: Discovery process enables devices to find each other Pairing is a one-time process that creates a private link between two devices for secure communication Unites them with a password or passkey Creates a PAN Connecting allows the paired devices to actually transfer information Connecting is done on a regular basis Master must be turned on first

Operating Range

Bluetooth wireless technology can operate over a distance of 10 meters or 100 meters depending on the Bluetooth device class.
Class 3: ~1 meter or 3 feet
Max permitted power 1 mW Max permitted power 2.5 mW Most commonly found in mobile devices and rechargeable devices Max permitted power 100 mW Used primarily in industrial use cases
Class 2: ~10 meters or 33 feet
Class 1: ~100 meters or 300 feet
Bluetooth Interfaces with HAs
Bluetooth requires no connection between Bluetooth-enabled devices and Bluetooth transceiver Bluetooth transceivers cannot yet be integrated directly into hearing aids
Use in hearing aids requires a secondary peripheral device called a Gateway device Most devices use the BT relay in a bidirectional mode
Power consumption Size of components
Bluetooth Chips 2000 - 2006

Yantz and Preves, 2007

Bluetooth connectivity with Hearing Aidscurrent approaches
BT to FM relay FM receiver DAI boot HA e.g. Phonak SmartLink BT Receiver Inductor HA Telecoil
e.g. Artone BT neckloop, MaxIT BT neckloop, Beetle H2ST BT Receiver DAI to HA e.g. GNResound Azure BT accessory BT to NFMI relay NFMI HA receiver

e.g. Oticon Streamer, Phonak iCom and Siemens Tek Adapted from Yantz and Preves, 2007
Wireless technologies: Basic comparison
Radio Frequency Power consumption Range One or 2-way communicatio n Security Interference susceptibility Audio bandwidth Latency (delay) Dedicated FM 72-76 MHz or 216217 MHz High > 100-150 1-way Low Medium 7.5 kHz < 2 ms Bluetooth 2.4 GHz NMFI 10-15 MHz Telecoil N/A
High < 33 Both High Low 3.4 kHz (HDP) 10 kHz (A2DP) > 10 ms (HSP) > 100 ms (A2DP)
Low 2-3 Both High Low 10 kHz <5 ms
Low Several cm 1-way High High Depends on telecoil response Depends on group delay in HA

Bluetooth via Induction

Unlike traditional induction neckloops and silhouettes, these devices require no connection between the phone and the head Can be used with telecoil-equipped hearing aids or cochlear implants Advantages: lower cost, ease of use Disadvantage:
Increased chance of picking up electromagnetic interference in addition to radio frequency interference Telecoil-response influences how person ultimately hears
Artone Bluetooth Induction Neckloop
Amplified inductive neck loop and Bluetooth transceiver with built-in microphone and interchangeable colored faceplates Wireless connectivity between HA/CI and cell phone, computer or other Bluetooth-enabled device Single multi-function button to answer/end calls Volume control

Specifications

Bluetooth v2.0 Supports Headset HSP and Hands-free HFP Passkey: 0000 Rechargeable Lithium-ion battery
Talk time: up to 8 hours Standby time: up to 240 hours USB charger cable; car charger adapter
Class 2 Operating range Cost: $165.00
MaxIT Bluetooth Induction Neckloop
Amplified Inductive neck loop and Bluetooth transceiver with built-in microphone and interchangeable alkaline or re-chargeable Ni-MH AAA battery Hands-free Connectivity with Bluetooth-enabled cell phones and computers Single multi-function button to answer/end calls Volume control
Compatible with Bluetooth v2.0 and v1.2 Supports HSP and HFP profiles Passkey: 0000 Rechargeable Ni-MH battery
Talk time: up to 15 hours Standby time: up to 500 hours USB charger cable; car charger adapter
Can be used with Alkaline AAA batteries Class 2 Operating range Cost: $145-160.00
Beetle H-2ST Bluetooth Silhouette and neckloop
Mini-Bluetooth lapel-clip transceiver with volume controls Choice of interchangeable single or dual induction silhouettes or neckloop Barrel-shaped, multifunction button with builtin microphone Wireless connectivity to Bluetooth-enable cell phones, computers, and personal audio devices that use the stereo A2DP Bluetooth profile
Compatible with v1.2 Supports HSP, HFP and Advanced Audio Distribution (A2DP) Passkey: 0000 Rechargeable Lithium-ion battery
Class 2 Operating range Cost: $159.00
Talk time: up to 4 hours Standby time: up to 70 hours USB charger cable

Telecoil as the last link
Susceptible to EM interference Telecoil orientation For optimum reception, T-coil should point in the direction of the magnetic field Verification of Telecoil response is essential Programmable telecoil is preferred Should be programmed to provide desired response Verification of telecoil response recommended! Coupler or real ear measures Input source Telewand

Telecoil response

Mic Telecoil

Telecoil

Telecoil response when pt arrived
Telecoil response after programming
Bluetooth via DAI GN Resound Azure
BT wireless headset accessory For use with Azure AZ 60 models only Clips onto the bottom of the hearing aid Stays off while connected until phone rings
Answer call by pushing button on headset or on phone Hearing aid automatically turns off external mic and turns on cell phone mic Available ONLY in Europe!

GN Resound Azure

Bluetooth gateway
A Bluetooth gateway is a small body-worn BT transceiver that can detect short-wave radio signals from Bluetooth-enabled devices Converts the signal into another format for retransmission to the hearing aid All permit bi-directional transfer of audio communication Frequency Modulation (FM)
Phonak SmartLink Requires FM receiver attached to hearing aid OticonStreamer Phonak iCom Siemens Tek Sends signal to NFMI equipped hearing aids
Digitally modulated near-field magnetic induction (NFMI)
Near-Field Magnetic Communication Proprietary wireless technology developed, patented and licensed by Aura Communications. NFMI communicates wirelessly by coupling a low power, non-propagating, quasi-static magnetic field between devices Works on the principle of magnetic induction
Creates a weak magnetic bubble of 4 to 6 feet in diameter in which it works
A magnetic field is generated on a carrier frequency and digitally modulated Receiver circuitry in the HA demodulates this signal Communication can be 2-way and the signal can be encoded for security
Ensures secure encoded communication and reduced susceptibility to interference

NFMI advantages

Magnetic communication is not blocked or reflected by objects, it is free from the interference, nulls and fades that are frequently an issue with RF solutions. Extremely small components
The entire NFMI receiver is implemented in silicon on the HAs integrated circuit and is small enough to fit inside custom HAs
Lower Power consumption than BT: about 100 nanowatts
Increases power consumption by only 10%
Range: 1 meters Frequency: 10 to 15 MHz.

Phonak SmartLink

BT-to-FM relay 3 solutions in one device
FM transmitter with 3 mic modes HA remote control Bluetooth transceiver for mobile phone use Not a direct BT signal Converts BT to FM signal which is not secure

Uses 2 technologies

Specifications Bluetooth Core v1.1 Supports Bluetooth profiles HFP and HSP Class 2 operating range For practical use with cell phones ONLY Quality poor for audio Uses protected code: 1234 and not universal code of 0000 Can be connected to only 1 BT device at a time Have to disconnect 1st BT device in order to pair with another BT-enabled device

Phonak iCom

Only works with Phonak Naida and Exelia BTE hearing aids and Exelia FS/HS/ITC custom aids Doesnt work with petite custom aids Neckloop serves as antenna Uses Digital Coded Induction technology or NFMI to stream signal to hearing aids EZBluetooth permits adjustable gain increase for the streamed signal and HA mic attenuation
Specifications Class 2-operating range Bluetooth v1.2 Bluetooth profiles supported HSP, HFP, A2DP 1.0 Passkey: 0000 Max 8 simultaneous paired devices Rechargeable Lithium-ion battery 5 hours BT streaming Standby up to 30 hours 11 hours audio streaming via cable 10 hours streaming via FM system

Oticon Streamer

Bluetooth interface for Oticon Epoq hearing aids Neck worn Streamer receives Bluetooth or DAI signals and transfers it to aids using NFMI NFMI technology used in Oticons RISE platform is called earStream Variant of NFMI 120,000 bits per second Also functions as a remote control for volume and program adjustment Max 8 paired BT devices at one time
Bluetooth compliance Version 2.0 Supports all relevant Bluetooth profiles Advanced Audio Distribution Profile (A2DP) Headset Profile HSP Hands Free Profile HFP Passkey: 0000 Bluetooth Range: 10 meters (class 2) EarStream range:.5 meters

NFMI to HAs

Bluetooth device & Streamer

Siemens Tek

Tek Connect communicates wirelessly with Siemens HA using NFMI/e2e wireless
Works only with Siemens Pure 700 & 500 BTE RIC and CIC, Explorer 500 P BTE
Doubles as a remote control 2.5 mm stereo input plug for hardwired connection to audio devices

Siemens Tek Connect

BT connectivity with cell phones and other devices
Bluetooth compliance Version 2.0 Bluetooth profiles supported HSP, HFP, A2DP 1.0 Passkey: 0000 Tek Connect needs to be within 1 meter or 3 feet from the HAs for NFMI transmission Recommend that it is worn around the neck with the lanyard

Bi-directional Answer/end call on Tek Connect
Tek Transmitter adapter pre-paired with Tek Connect
Each Tek transmitter only works with one Tek Connect
Eliminates need for pairing; easier to use Claims reduced transmission delay ~ 65 ms Claims less echo, better audio/video synch Use with TV, video, stereo, etc 2.5 mm stereo connector
Multiple Tek transmitters requires multiple Tek Connect units
Separate programmable programs for use with Tek Connect & Tek transmitter
With the exception of Program #1 (universal) can select input

Signal Prioritization

Tek Transmitter Tek Connect BT signal Select BT + Mic or BT only Select Tek Tx + Mic or Tek Tx only Level of Tx/BT versus mic adjustable
Cell phone highest priority Direct connected device 2nd highest priority Tek Transmitterlowest priority
Bluetooth-enabled Devices and Adapters
Bluetooth-enabled landline phone
AT&T EP5632 5.8 GHz Bluetooth Cordless telephone Pair up to 8 Bluetooth devices; max 2 paired devices connected at one time Built-in answering machine Very easy to pair/connect
Also works with Artone BT neckloop; MaxIT BT neckloop Cost: $99.95
Permits entry of passkey Oticon Epoq Phonak iCom Siemens Tek Connect Phonak SmartLink

Compatible with

Connection to Non BluetoothEnabled Devices
BT Adapters are available for
Non-BT cell phones Landline phones Computers Stereos iPod/MP3 players TVs
Kensington Bluetooth USB dongle
Plug-in USB device for laptop or PC Permits cable free connections between computer and other Bluetooth devices Stream audio from PC/laptop Watch DVD Listen to iTunes Works with: Epoq Streamer Phonak iCom Siemens Tek Connect

Specifications:

USB 2.0 Bluetooth v.2.0 compliant with EDR Class 2 operating range Support Win XP, Vista and Mac OSX Computer software permits entry of any passkey Cost: $21.99 at Best Buy
Sony TMR BT8iP BT iPod Adapter
Wireless BT transmitter for streaming high quality stereo music from iPod Connects to bottom of iPod iPod classic iPod mini iPod Nano iPod Touch Compatible with Oticon Streamer Phonak iCom Siemens Tek Connect
Specifications: Bluetooth v2.0 + EDR Profiles: A2DP, AVRCP Class 2operating range Transmitter power supplied from iPod Supported passkeys: 0000, 1234, 8888

Cost: $76.99 at Best Buy

ARTONE TVB
Wireless communication accessory that connects to audio sources iPod TV radio Works with Oticon Epoch, Phonak iCom, Siemens Tek Connect Class 2-operating range 10 meters or 33 ft Rechargeable battery $99.00
Jabra A7010 Bluetooth Hub
Connectivity hub Bluetooth enabler for landline phones

Works with most standard corded desk phones both analog and digital PBX and IP Compatible with

Not cordless

Oticon Epoq Artone BT Neckloop MaxIT BT Neckloop
Bluetooth 2.0 specs Class 2: operating range 10 meters or 33 ft Sound enhancements: Digital sound enhancement via DSP technology and eSCO Bluetooth Audio Link Cost: $80.00

Hybrid Solutions

Mixture of technologies Hardwired and wireless
Hardwired Connection to Landline Phone
Link landline phone to gateway device using Radio Shack MiniRecorder Control #43-1237 Connects to mic/aux input on transmitter Mono-stereo adapter needed Permits wireless, binaural reception of phone signal via gateway device in each hearing aid
Works with Phonak SmartLink Phonak iCom Siemens Tek Connect Does NOT work with Oticon Epoq Cost: $18.00
Requires that user speak into handset or headset mic
SmartLink Audio Input Limitation
Adapter has direct audio 3.5 mm input with auto detection
If auto FM is used Highly dependent on level of input signal If input signal drops in gain or pauses, transmitter reverts to FM input

Audio input Mic input

Use 2.5 mm mic input instead if hardwiring transmitter to MP3 player to other audio device
3.5 mm audio jack permits hardwired connection to audio devices and wireless connection via NFMI to hearing aids Universal DAI plug for Phonak microMLXs FM receiver EZAudio control permits adjustable gain increase for the streamed signal and HA mic attenuation
Streamer has 2.5 mm audio input jack for hardwire interface with other audio sources E.g. Sennheiser 820s FM system

BT Summary

Variety of Bluetooth options currently exist Elimination of wires is a key advantage BT options exist that are cheaper than FM or IR Like ALDs, counseling, demonstration, education necessary for adoption and successful use of technology Compatibility of BT devices can be complex and requires knowledge on the part of the user Pairing and connection of devices can also be challenging for some users
Operating range much shorter than FM
Poor application to large area applications
Church, classroom, conference hall
Communication between devices must be direct
Point-to-point technology Pairing is required and not extended to other devices outside that pairing Not currently an alternative to group FM/IR systems Point-to-multi-point devices Bluetooth profile has been developed which may be used in future applications

References

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