Safe Listening! How I Enjoy My Music and Avoid a Silent Future (ITU and WHO) Brian Copsey

Transcription

1 Safe Listening! How I Enjoy My Music and Avoid a Silent Future (ITU and WHO) Brian Copsey

2 Safe Listening! How I Enjoy My Music and Avoid a Silent Future (ITU and WHO) This presentation focuses on those many children and adults using Assistive Listening Devices and T-Coil systems within their hearing aid WSIS Forum Geneva May

3 Existing Situation: Radio Assistive Listening Devices use radio spectrum to provide a link between the hearing aid and a microphone held by a speaker( e.g. teacher) or between a mobile phone and hearing aid (Bluetooth protocol) Or between TV and hearing aid The majority of these systems use the GHz spectrum which they share with WiFi and thousands of other systems, WSIS Forum Geneva May

4 Existing Situation: T-Coil T-Coil is an magnetic field system using a wire loop to generate inductive currents which are picked up by a receiver in the hearing aid. The majority of hearing Aids contain a T-Coil receiver WSIS Forum Geneva May

5 Wireless media gateway 5

6 Education I would like to deal first with the Education situation: Radio aids have the potential to greatly enhance the listening experience of deaf children by improving the audibility of speech in situations where distance, background noise and reverberation make listening difficult Ref: NDCS Quality Standards for the Use of Personal FM Systems, 2008 WSIS Forum Geneva May

7 Education use WSIS Forum Geneva May

8 Education What could go wrong with such a wonderful use of radio spectrum? Well whilst systems made by the major hearing Aid manufacturers are classed as medical devices and contain an audio level limiter a few companies marketing Tour Guide Systems are now targeting schools and other places of learning WSIS Forum Geneva May

9 Education A tour guide system is designed for adults with normal hearing and who (one hopes) will use the volume control sensibility. In the case of most Children the normal situation is as loud as possible (even though volume and clarity are not the same thing) In a child with already damaged hearing this has the possibility of increasing the damage WSIS Forum Geneva May

10 Comparison Via GN Otometrics HIT Of Tour Guide System Vs Hearing Aid System using N7 NHS(UK) Audiogram Naida SP Hearing Aid System Note: a 3dB difference means twice the power WSIS Forum Geneva May

11 Tour Guide System WSIS Forum Geneva May

12 Standard NHS evaluation audiograms HL ISO Category k 1,5k 2k 3k 4k 6k N1 16 Very Mild N2 31 Mild , N3 46 Moderate N4 63 Moderate/Serve N5 76 Severe 65 67, , N6 89 Severe 75 77, , N7 103 Profound 90 92, WSIS Forum Geneva May

13 T-Coil Audio frequency induction loop systems (AFILS), also known as hearing loop systems, have been on the market since the middle of the twentieth century, with the first recognisable patents appearing circa AFILS are primarily used to facilitate improved communication to people with impaired hearing and are an important tool in the reduction of discrimination against disabled people. WSIS Forum Geneva May

14 T-Coil Use AFILS are installed in places of worship, places of entertainment, places of education, ticket booths and service counters etc., as well as in domestic situations, providing huge benefits to users with impaired hearing. AFILS provide an audio frequency magnetic field that couples with a receiving coil (Telecoil) fitted in hearing aids, cochlear implants and loop receiving and testing devices. This magnetic field is generated in a wire loop that is fed by an audio frequency amplifier which is capable of driving current through the induction loop which, in turn, is fed from external signals such as those generated by microphones, audio-visual equipment and musical instruments. AFILS operate below 9kHz and have a very limited range (some few metres) and there is no known evidence of interference with radio equipment WSIS Forum Geneva May

15 Possible Problems There are a range of new technologies referred to as Wireless Power Transfer or Wireless Power Transmission (WPT) under development. These allow the transfer of Electrical Power without the use of a cable. Examples are: charging a mobile phone or bus heating an electric kettle. Charging domestic appliances in a kitchen WSIS Forum Geneva May

16 Problem 1 Whilst, so far no WPT systems are using the same frequencies as the T-Coil system, they are close neighbours. Many bus stops have miniature wire loops to inform those with hearing aids of the Bus timetable or other information An electric Bus requires a very high charging current. When charging is switched on and off there may be a large transient pulse which will affect the T-coil loop and receiver, producing a verylarge click or splat in the users ear In order to verify if there is a problem, thanks to Ofcom UK we are carrying out testing latter in May WSIS Forum Geneva May

17 Problem 2 T-coil receivers in many hearing aids are permanently on therefore in a kitchen using WPT for say a kettle the same situation as the bus occurs. We do not know how far both in frequency and physical distance pluses will travel We are in the process of arranging practical testing to verify the situation WSIS Forum Geneva May

18 Radio Interruptions ALDs use a number of radio frequencies, the prime frequency band is the MHz which is the only worldwide spectrum available for the Short Range Device family, (ALDs, WiFi, Bluetooth and many more). The adjacent band GHz has now been allocated for mobile phones. Practical testing has shown that dependant upon the proximity of a mobile phone using this spectrum (1-5M) either interference or loss of audio will occur WSIS Forum Geneva May

19 Radio Interruptions in the MHz Band The MHz band is used for cordless Audio within Europe, this is home to many ALD systems, in recent years mobile allocations below 862MHz have produced similar proximity problems to those at 2.4GHz. Dr H.B Karcher has carried out testing with cordless headphones(very similar to ALDs ) and the link below provides access to his work WSIS Forum Geneva May

20 Conclusions Safe Listening! How I Enjoy My Music and Avoid a Silent Future : this is a much more complex and wide spread situation than it first appears which needs to be constantly monitored for ALD and hearing aid users as pressure on spectrum for new systems increases. Most of those working on new technologies, other than the mobile phone industry, when approached are helpful and are attempting to minimise any problems via practical testing and the standardisation process. At the same time manufacturers of ALDs and hearing aids are attempting to find solutions to the problems (not easy in such miniature devices) The ITU Joint Coordination Activity on Accessibility and Human factors monitors these and similar issues, informing other groups as information becomes available WSIS Forum Geneva May

21 Thank you for your attention For any questions or further information please contact Brian Copsey : BC@copsey-comms.com WSIS Forum Geneva May