1、 Recommendation ITU-R M.1076-1 (02/2015) Wireless communication systems for persons with impaired hearing M Series Mobile, radiodetermination, amateur and related satellite services ii Rec. ITU-R M.1076-1 Foreword The role of the Radiocommunication Sector is to ensure the rational, equitable, effici
2、ent and economical use of the radio-frequency spectrum by all radiocommunication services, including satellite services, and carry out studies without limit of frequency range on the basis of which Recommendations are adopted. The regulatory and policy functions of the Radiocommunication Sector are
3、performed by World and Regional Radiocommunication Conferences and Radiocommunication Assemblies supported by Study Groups. Policy on Intellectual Property Right (IPR) ITU-R policy on IPR is described in the Common Patent Policy for ITU-T/ITU-R/ISO/IEC referenced in Annex 1 of Resolution ITU-R 1. Fo
4、rms to be used for the submission of patent statements and licensing declarations by patent holders are available from http:/www.itu.int/ITU-R/go/patents/en where the Guidelines for Implementation of the Common Patent Policy for ITU-T/ITU-R/ISO/IEC and the ITU-R patent information database can also
5、be found. Series of ITU-R Recommendations (Also available online at http:/www.itu.int/publ/R-REC/en) Series Title BO Satellite delivery BR Recording for production, archival and play-out; film for television BS Broadcasting service (sound) BT Broadcasting service (television) F Fixed service M Mobil
6、e, radiodetermination, amateur and related satellite services P Radiowave propagation RA Radio astronomy RS Remote sensing systems S Fixed-satellite service SA Space applications and meteorology SF Frequency sharing and coordination between fixed-satellite and fixed service systems SM Spectrum manag
7、ement SNG Satellite news gathering TF Time signals and frequency standards emissions V Vocabulary and related subjects Note: This ITU-R Recommendation was approved in English under the procedure detailed in Resolution ITU-R 1. Electronic Publication Geneva, 2015 ITU 2015 All rights reserved. No part
8、 of this publication may be reproduced, by any means whatsoever, without written permission of ITU. Rec. ITU-R M.1076-1 1 RECOMMENDATION ITU-R M.1076-1* Wireless communication systems for persons with impaired hearing (Question ITU-R 254/5) (1994-2015) Scope This Recommendation provides the technica
9、l and operational characteristics for wireless accessibility of hearing aids to public, home and personal audio services operating in the land mobile service. Keywords ALD, ALS, assistive listening device, hearing aid, wireless accessibility of hearing aids Acronyms and abbreviations ALD Assistive l
10、istening device ALS Assistive listening systems DSP Digital signal processing e.r.p. Effective radiated power LAN Local area network The ITU Radiocommunication Assembly, considering a) that many forms of hearing impairment cannot be satisfactorily improved by audio amplification only; b) that a numb
11、er of means have been used to transfer speech signals to the listeners hearing device. These means include infrared radiation, use of the magnetic induction internal to current loops, including operation at audio frequencies, VHF and UHF radio and the external induction field of a radiating antenna;
12、 c) that some 10% of people suffer from mild to severe hearing loss; d) that users of aids for hearing impaired (hearing aids including assistive listening devices) are found worldwide; e) that personal uses include access to mobile phone and personal audio applications; f) that home usage includes
13、access to broadcast television, broadcast radio, emergency notification and alarms; g) that public usage includes access to points of sales, counters, public address systems in areas such as airports, train stations, religious places, theatres, events and cinemas; h) that the practical application o
14、f infrared systems and audio frequency induction loops to communicate with persons with impaired hearing should also be considered for some applications, * The Director, Radiocommunication Bureau, is requested to bring this Recommendation to the attention of the ITU-T Study Group JCA-AHF and the Int
15、ernational Electrotechnical Commission (IEC). 2 Rec. ITU-R M.1076-1 recognizing a) that Resolution 175 (Rev. Busan, 2014) of the Plenipotentiary Conference resolves to take account of persons with disabilities in the work of ITU, noting a) that for public use it may be beneficial to have a standardi
16、zed wireless system, operating on globally harmonized tuning range; b) that there is a wide divergence in spectrum used around the world for assistive listening devices; c) that administrations need to carefully consider suitable harmonized frequency ranges for the operation of wireless systems for
17、hearing impaired person, recommends that the technical and operational characteristics for radiocommunication systems for persons with impaired hearing given in Annexes 1 and 2 should be used. Annex 1 Operational characteristics of wireless communication systems for persons with impaired hearing 1 S
18、ystem concepts Historically, hearing aids consisted of little more than basic “miniature audio amplifiers” placed in or behind the ear(s) solely boosting the incoming sounds. As semiconductor technology has evolved and become miniaturised, hearing impaired people enjoy extremely sophisticated digita
19、l systems incorporating a range of communication capabilities. State-of-the-art technology uses specialized digital signal processing (DSP) technology that is advanced enough to fulfil the stringent mechanical (ultra miniature) and power consumption (only one small single cell battery) requirements
20、that are specified for modern hearing aid devices. DSPs manipulate the incoming sound spectrum mathematically, converting it into a digital representation; programmable software then manipulates this digital representation to achieve: background noise reduction; correction of user specific deficienc
21、ies; enhancement of sound cues and other listening parameters used by the brain to reconstruct normal hearing. Hearing aids contribute to user safety, comfort and enjoyable listening experience. However, real life offers an incredible richness in different listening environments in some of which eve
22、n the most sophisticated hearing instruments show only a limited benefit. Examples of acoustic environments or listening situations where the performance of conventional hearing instruments can substantially be improved by applying additional communication devices are the following: reverberant envi
23、ronments such as big churches or lecture halls; communication over larger distances, e.g. in a lecture or in a classroom; Rec. ITU-R M.1076-1 3 communication on the telephone, especially cell phones. situations with large background noise levels (e.g. rooms, halls and areas with multi-talker speech;
24、 engine noise inside or outside of trains and busses, etc.). In these environments the application of assistive listening systems (ALS) based on wireless communication technologies offer substantial additional benefits and significantly improve speech intelligibility. The advent of digital broadcast
25、ing is now displacing some of the frequencies where these wireless ALSs have traditionally operated. In North America and Europe, approximately 1 person in 10 has some form of hearing loss, from mild to severe. Today only 20% of these people are assisted by hearing aid technology. The binaural rate
26、(wearing two hearing aids: one left and one right) is 75% to 80% in North America, 60% in Europe and 10% to 12% in the rest of the world. Reasons for such low adoption rates in general vary from negative stigma associated with wearing cosmetically non-appealing devices to high cost and certain types
27、 of hearing losses that could not be corrected. Recent progress made in binaural hearing health revealed that having for example the right hearing aid being able to communicate with the left hearing aid and vice versa helps achieve another level of breakthrough in restoring someones hearing. This al
28、so directly contributes to the safety of that persons listening environment, for example directionality of sounds can be better perceived, in cases such as an approaching ambulance or fire truck which cannot be seen but only heard, is physically located. In some instances where one ear is totally im
29、paired, sounds captured from that side of the head can be relayed to the other ear and processed such as that person experiences full 360 hearing again. A major role of allowing the hearing impaired to communicate and also enjoy similar experiences to those with normal hearing has been played by the
30、 Telecoil system which is in worldwide use. Unfortunately these are difficult or impossible to install in large public places such as airports and train stations and are both expensive to install and maintain. Also building owners are often reluctant to allow them to be installed. In addition they o
31、nly supply a single low quality voice channel. This lack of flexibility and cost have given rise to an explosion of radio based systems for most teaching, especially sports coaching1 and domestic use where multiple channels are required2. Hearing aids can be described as body worn therapeutic medica
32、l devices used to provide improved medical treatment of a patient. Therefore, they are subject to the very same constraints as all other body worn medical devices: They perform therapeutic tasks aimed at treating, curing, hence bettering patients lives. They are installed/worn in and around the body
33、. They are subject to severe power consumption constraints, due to their discreet mechanical size, that commands a very small source of energy (single cell battery). A harmonized, worldwide deployable tuning range would facilitate the use of these devices for international travellers in public areas
34、. These devices rely on the radio spectrum to be optimized in terms of energy spent for range and link robustness achieved, hence a low noise floor and minimal interference band, where body tissue absorption and spectrum usage density are taken into account. 1 Football and horse riding are some of t
35、he many sports now using this equipment for coaching. 2 Many schools require in excess of 25 channels. 4 Rec. ITU-R M.1076-1 If these devices are exposed to an environment of high emissions the user could experience pain and possible damage3 to the ear drum and/or other physical incapacity. 2 Induct
36、ion-Loop system (often referred to as Telecoil) Inductive systems rely on coupling an audio amplifier, e.g. for the microphone of a speaker in a lecture hall or a teacher in a classroom, directly to an induction loop system which basically directly transmits the rather low frequency audio signal as
37、a radiated time varying magnetic field. Induction loop systems use a large coil antenna integrated in the floor of a large room for radiating the magnetic field. Once properly installed, and given that the listeners hearing aids include “T” coils, an IL system is undoubtedly the most convenient and
38、possibly the most cost effective ALS. To hear the audio, all a person has to do is enter the looped area and switch his/her personal hearing aids to the telecoil position. As long as the persons hearing aids include “T” coils, he or she always has an assistive device “receiver” available. However th
39、is technology also has some technical drawbacks which limit the range of application of this technology. The physics of inductive coupling requires the receiving coil (T-Coil) to be perpendicularly oriented to the field of the sending coil or induction loop. This is sometimes difficult to achieve be
40、cause the orientation of the induction loop is fixed and the orientation of the T-Coil depends on how it is built into the hearing instrument and the persons orientation. Furthermore, the inductive transmission strongly depends on the distance between sender and receiver which sometime results in a
41、weak signal. The receiver also always has to remain within the loop in order to receive a signal. External interferences (from power lines or fluorescent lights, computer monitors copiers, fax machines, cell phones, etc.) creating background noises or distortions in the hearing instrument, are diffi
42、cult to remove. Next, in school environments, several different systems are required for different classrooms. When applying two different systems in neighbouring classrooms it often is difficult to avoid spill over from one induction loop system to the next although recently technological progress
43、has been made for reducing this problem. Furthermore, induction loop systems are not portable and can only be applied where they have been pre-installed. 3 VHF and UHF systems Current systems employing VHF and UHF FM (sub 2 000 MHz) radio transmission are capable of providing communication over dist
44、ances greater than those using the radio induction-field system, as they employ transmission via a radiation field which decays less rapidly with distance than does an induction field. As a consequence, VHF and UHF radio transmission systems require that each transmission in any locale, such as a sc
45、hool classroom and its environs, be assigned a separate frequency channel. VHF and UHF reception is generally less susceptible to interference from natural and man-made noise than is reception at lower frequencies and systems employing VHF and UHF radio transmission will be useful in many circumstan
46、ces to avoid local problems of interference which affect the operation of the radio induction-field system. Radiocommunication systems intended only for short-range communication are capable of producing high field strengths at their required working distances, without radiating significant levels o
47、f power. Exploitation of the resulting possibilities of shared spectrum usage can result in improved spectrum utilization, and may allow large numbers of channels to be made available, for example to satisfy the 3 http:/www.access-board.gov/research/interference.htm http:/www.fda.gov/Radiation-Emitt
48、ingProducts/RadiationEmittingProductsandProcedures/ HomeBusinessandEntertainment/CellPhones/ucm116327.htm Rec. ITU-R M.1076-1 5 requirements of large schools for any children with impaired hearing which is increasingly a requirement of national legislation and an objective for children above five we
49、eks old in many countries. Equipment takes a number of physical forms from add on receivers for behind the ear systems to belt mounted units and necklace units. Currently narrow band FM systems predominate for teaching systems with Bluetooth connectivity for mobile phones and some domestic equipment using radio local area network (LAN) technology for connection to multimedia terminals. Scarcity of spectrum has meant that the narrowband fixed frequency channel equipment using a 100% duty cycle is not suitable for sharing with other services or short ran
