RFHIC
“A Wider Market for Digital Mobile Phones - Meeting the Needs of Hearing Impaired People.”
A Report
from
The Radio Frequency Hearing Impaired Committee
of
The Radiocommuncation Agency
edited by M.C. Martin OBE and published by PhoneAbility
Contents
1. Executive Summary
1.1 The issues
The explosive growth of digital mobile communications worldwide is all too apparent and yet a lack of functionality for hearing impaired people, or compatibility between hearing aids and mobile phones renders many of these new products unusable.
The report concentrates on the needs of hard of hearing people who use speech and residual hearing as their main means of communication. This is the largest group of people who are affected by problems in using mobile phones and for whom technical solutions are possible. However the needs of profoundly deaf people who cannot benefit from amplification are of great importance. The well-known problem of using text communication with mobile phones requires further action.
Whilst digital mobile phones and hearing aids (as stand alone devices) are declared to be compliant with all current regulation and legislation, a problem exists when these two devices are used in close proximity to each other i.e. when a hearing aid user wishes to use a digital mobile phone in the same manner as everyone else.
All mobile phones in the UK are now digital. Digital mobile phones can cause severe interference with hearing aids, whereas analogue phones did no previously present a problem. The interference may be extremely annoying, or even so loud that it swamps the call hearing aid users want to hear.
Concerns are therefore prevalent that hearing impaired people may have diminished or no access to the mobile telephone network. A direct consequence of this interference is an inability to access telephone services and in particular the emergency services as well as being able to maintain social contacts.
Most mobile phones do not provide additional audio amplification, inductive coupling or suitable interfaces that are common features of many fixed telephones.
The report identifies the need for a more active participation in this area by both telecommunication service companies and manufacturers of mobile phone equipment. The hearing aid industry has made significant strides forward in increasing the immunity of their products but has not publicised these benefits. Neither industry has come to any agreement on a method that will allow consumers to judge what products work satisfactorily together.
The availability of add on devices has been seen as a panacea for resolving the problems and has resulted in a lack of action by the telecommunications industry and has not allowed the development of a secondary market in such devices.1.2 Recommendations
- Manufacturers and service providers of mobile phones should work together to achieve interoperability between hearing aids and mobile phones and achieve some choice for consumers.
- Manufacturers of hearing aids should make more generally available information on the immunity of hearing aids.
- Manufacturers of mobile phones should standardise on common interfaces for add-on devices for hard of hearing and deaf people.
- Research should be undertaken to evaluate the effects of wearing different types of hearing aid with different mobile phones, as limited work has been undertaken on the subjective aspects of user problems
2. A Wider Market for Mobile Phones: Meeting the Needs of Hearing Impaired People
2.1 Aims of this document
This document identifies current problems and developments that aim to minimise them,
- indicates those industries and institutions that need take an interest,
- explores technical measures that could be considered,
- highlights the potential commercial opportunities that might be exploited, highlights the benefits that may accrue to hearing impaired people.
2.2 Who needs to have an interest?
The anticipated audience for this document is: -
- Mobile telephone manufacturers; to understand users needs and facilitate the development of phones which are useable by a range of customers other than their normal market, standard interfaces for their equipment and address electromagnetic compatibility issues related to the use of hearing aids.
- Mobile phone service providers; to assist with the development of facilities and services accessible by hearing impaired people. To encourage and participate in the standardisation of equipment interfaces, including standard text features/protocols for use throughout their systems.
- Hearing aid manufacturers; to continue to address electromagnetic compatibility issues related to the use of mobile telephones and participate in the development of standard interfaces in conjunction with mobile telephone manufacturers.
- Public interest groups; to promote the availability of solutions to current problems and to participate in developments to ensure appropriate consumer input.
- Regulators and legislators; to ensure that where market forces do not provide the necessary basic equipment and services to allow access to mobile phone services appropriate regulation and legislation is implemented.
2.3 The size of the problem
Estimates of the numbers of people in the population who have hearing problems vary according to the manner in which hearing loss is defined. Two approaches to this are often used to determine the numbers. One may be described, by some, as a medical model and involves measuring the actual hearing loss of individuals using some form of audiometry. The other is a questionnaire approach that simply asks people if they have a hearing problem and what it is. It is true to say that simply measuring levels of hearing does not necessarily indicate levels of function. However it is equally true to say that the questionnaire approach does not elicit necessarily accurate responses due to the fact that people are known to be defensive about their hearing problems. The importance of understanding these difficulties in assessing numbers is to appreciate why there are so many different statistics available that apparently give quite varying answers.
A further complication is that the degree of hearing loss and the individual’s ability to understand speech, particularly over the telephone, varies considerably. Furthermore the incidence of hearing loss is very much age dependent.
However the best set of statistics that are currently available are those produced by the MRC Institute of Hearing Research from the National Study of Hearing in the UK, (1). While these may be denigrated by some as being part of a medical model of deafness they do provide an accurate and scientifically based set of statistics that can be used for discussion. Table 1, taken from Davis (2), indicates the numbers (in thousands) of people with hearing impairment as a function of age and severity of impairment. The severity is an average of hearing impairment for the better ear averaged over 0.5, 1, 2 and 4kHz.
Table 1. Estimates of the number of people (in thousands) in the UK with hearing impairments, as a function of age group and severity of impairment for the better ear, averaged over the mid-frequencies 0.5, 1, 2 and 4kHz.
Severity |
18 - 60 |
61 – 80 |
81 + |
Total |
25+ |
2131 |
4486 |
1864 |
8580 |
35+ |
917 |
2523 |
1700 |
5140 |
45+ |
471 |
1132 |
1337 |
2940 |
65+ |
136 |
294 |
469 |
898 |
95+ |
38 |
34 |
78 |
150 |
People with hearing losses of less than 45dB are likely to hear reasonably well on the telephone due to the gain provided by the telephone system. People with losses of 45 dB or more are likely to have difficulties and a proportion of them will be hearing aid users. Those with 95dB or more losses will need to use textphones and are unlikely to benefit from amplification on its own. However they may have sufficiently good speech to be able to talk over the telephone. The estimated number of hearing aid users in the UK is some 3% of the adult population, or some 2 million people, Davis (2), which can be seen to be considerably less than the number who should or could wear a hearing aid. This phenomenon is well known and steps are being taken to increase the usage of hearing aids.
2.4 Barriers to access
2.4.1 Lack of identity as a market group
People with disabilities are recognised to be one of the most disadvantaged sections of our society. Mobile phone technology has played a valuable part in enabling some people with a wide range of disabilities to access telecommunications services. However the major cause for exclusion of hearing-impaired people is because their disability affects speech communication through an inability to hear, or hear clearly, what is being said. While this is an obvious statement it needs to be reinforced because for most people that is what the telephone and telecommunications in general is about. The most common means of addressing this issue, after any medical intervention, is through the use of a hearing aid. Because of the lack of appropriate features and compatibility with hearing aids the means of minimising the problem when using mobile phones is being exacerbated. This group appears to have no identity within telecommunications marketing and its needs are therefore not sufficiently well addressed by manufacturers or service providers.
The United Nations resolution entitled the “Standard Rules for the Equalisation of Opportunities for Persons with Disabilities “[3], recognises that an individuals functionality within society depends on societies openness to accommodate people with differences as much as the functional limitations that identify a person as “disabled”. The term “disabled” is not one that the vast majority of hearing-impaired people would use to describe themselves and consequently they cannot be easily contacted through organisations for the deaf and hard of hearing and therefore represent a marketing problem.
Whilst many might have supposed that the significant number of disabled people might have been targeted by astute commercial policies focusing on the greater market share, this does not have seemed to be the case with regard to mobile phones. Development of new technologies, within Europe, has in many cases not addressed the needs of disabled people and in particular those who are hard of hearing or deaf.
2.4.2 Lack of suitable products
In order for there to be the same ease of access for hard of hearing and deaf people to using mobile phones as the rest of the population there has to be a range of readily available products to allow this to happen. At the present time there are very few products available.
The market for products can be divided into a number of sectors that include:
- People with smaller hearing losses who do not use hearing aids but may require additional amplification
- Hearing aid users that wish to use a mobile phone normally and require an assurance of the mutual compatibility of both devices
- Hearing aid users that wish to use inductive coupling between their mobile phone and hearing aid
- Profoundly deaf users who cannot make use of amplification and need easy to use, low cost text facilities with enhanced keyboard and screen facilities.
There are well-established solutions to the problems of hard of hearing people using the telephone, which the COST 219 project “Future Telecommunication and Teleinformatics Facilities for Disabled people” set out in its publication “Is anyone answering” in 1990 (4). These solutions have not in general been implemented with regard to mobile phones. Below are described a set of product features that are still relevant today.
2.4.3 Interaction of service providers and equipment manufacturers
An argument for the lack of suitable products for hard of hearing and deaf people is a circular one between service providers and manufacturers of equipment. The manufacturers will say that they will make what the service providers want but the service providers do not specify the products. The service providers say that they cannot provide the equipment because the manufacturers will not make it. The net result is inactivity on both sides.
2.4.4 Lack of marketing
Given the potential size of the market it would have seemed appropriate for there to be some widespread marketing of products, given that they were available. Much emphasis has been made of the size of the market but no attention has been paid marketing. There appears to be an attitude in many quarters of the mobile phone industry that this is a matter for the disability organisations to promote. What has not become clear to marketing people is that the vast majority of potential customers have little or no contact with disability organisations.2.5 Relevant product features
2.5.1 Primary and secondary features
With the rapid development of technology, and the focus on young people as customers in the mobile phone industry the potential for including features that would benefit disabled customers has been largely ignored. Indeed it can be argued that current designs make using mobile phones difficult for many disabled people. Consequently what might be called primary features i.e. features built into the phone at the design stage, are of limited use to many disabled people, particularly those who are hard of hearing or deaf. An example of a primary feature that makes the use of a mobile phone possible by a hearing aid user is the positioning of the antenna. Measurements (5) have shown that by positioning the antenna at a small distance from the head leads to a very large reduction in interference with hearing aids. This is a design feature in some phones but has never been promoted, but is highly effective in reducing the hearing aid interference problem.
Secondary features are those that are add-on to the standard model and require the consumer to purchase them separately. In addition they require separate, usually very small, manufacturers to produce these products. The lack of standard interfaces limits the development of such devices, as they often will only fit specific models thus limiting consumer choice. An ETSI report [16] reviews the range of possibilities with regard to interfaces and indicates the range of knowledge available.
2.5.2 Add-on devices as a solution
Hearing aid manufacturers have already achieved a great deal in increasing immunity to a level that now allows many new production hearing aids to be used directly with mobile phones, but there are likely to be limits to what may be achieved. In addition there will be for many years to come very large numbers of hearing aids in use that were designed before the interference problem was full recognised. By comparison, telecommunications manufacturers and network service operators appear not to have seen this as an issue that is worthy of investment.
2.5.3 Available devices
An interim solution for people with hearing aids with low immunity e.g. older aids, is to provide devices that can couple the phone to the hearing aid.
Hearing aids can be coupled to telephones in three general ways:
- acoustically, through the microphone of the hearing aid,
- through magnetic induction coupling to a hearing aid that has a pick-up-coil indicated by the presence of a “T” position on the user control,
- by direct electrical connection, if the hearing aid possesses an audio input facility.
The latter means of connection has been found to be impractical in many cases for two reasons. Firstly the number of hearing aids used by adults with this facility is very small and secondly, the leads to and from the aid are fragile and require special plugs at both ends.
Fig 1. Typical hands free kit available for most models of mobile phone
The concept of a hands-free kit may be considered as the basis for providing a means for allowing inductive coupling to a hearing aid. Figure 1 shows such a device, which allows the phone to be worn on a belt or held in the hand away from the hearing aid. This meets the essential requirement of increasing the distance between the aid and the phone thus reducing significantly the level of the interfering RF signal. It is essential however that the earphone produces sufficient audio frequency magnetic signal to be picked up by the hearing aid. A significant advantage of using induction coupling is that because the microphone in the hearing aid is switched off it reduces the effects of ambient noise around the listener.
An approach explored by one manufacturer is the use of an induction neck loop, fig 2. Although this device was found to work well, it had a short battery life and could not be considered universal; in addition it only fitted two models of that manufacturer’s large range of phones. A number of alternative means of induction coupling have been explored. These include a post auricular inductor (a small flat induction coil placed over their ear adjacent to a behind the ear hearing aid) and a pair of ‘silent headphones’, which produces a magnetic output but no sound.
However it must be appreciated that only a proportion of hearing aids have an induction pick-up-coil fitted and can use this means of coupling, it therefore does not provide a generic answer to the problem.
Fig.2. An inductive neck loop - The approach of one manufacturer.
Consideration has also been given to various appropriately designed acoustic coupling devices such as earphones, over-the-ear phones and loud speaking devices.
2.5.4 Implications of add-on devices review
A review, carried out by the HAMPIIS (Hearing Aids Mobile Phones Immunity and Interference Standards) project [5], of add-on devices clearly indicated that this approach to minimising the problem of hearing aid interference was viable and offered a solution, particularly for people using present day hearing aids with induction coupling facilities. There is however an absence of evidence that alternative approaches are being considered, such as the use of low acoustic impedance earphones (loudspeaker) which allow the hearing aid user to place the aid close to the phone without loosing low frequencies associated with close coupled earphones.
The finding that there was a considerable degree of uniformity with regard to the mechanical and electrical connection of devices to mobile phones opens the way to standardising for these characteristics: this could lead to a secondary market for a wide range of accessory devices aimed at the hearing impaired community.
2.5.5 User information requirements
One method of assisting hearing impaired users selecting compatible products could be for radio communications products to carry a declaration on the product or associated packaging that the equipment is compatible with a particular class of hearing aid. The same concept could also be applied to hearing aids. Clearly this would allow manufacturers of radio communications and “medical” equipment to facilitate access to their products and offer a service to a customer base that has yet to have its needs fulfilled.
The Radio Frequency Hearing Impaired Committee (RFHIC) currently provides a web site www.rfhic.org.uk, which provides a source of information for both the general public, and it’s own members. It is clear that greater use could be made of the Internet in disseminating information in a cost effective way to all parties.
3. Measurement methods
In order to be able to quantify whether or not there is an interference problem it is necessary to be able to make repeatable and reliable measurements. The quantities to be measured are:
- The level of interference signals that are likely to cause the user varying degrees of difficulty when using the hearing aid in the presence of a mobile phone.
- The level of immunity of the hearing aid to specified types of signal over a defined frequency range
- The level of radiation from the mobile phone that is present at the hearing aid when it is being used in a normal manner.
4. Standards
4.1 Product compatibility
While technical implementation of standards is almost certain in some areas, the widespread emergence of practical solutions for users of present day hearing aids will only come about through the concerted willingness of telecommunication companies and hearing aid manufacturers to address this issue in a consumer-friendly way.
In this area the hearing aid industry has made considerable strides with regard to standardising acceptable levels of immunity for hearing aids through the International Electrotechnical Commission (IEC) [6] and American National Standards Institute (ANSI) [7}.
In addition there has existed for many years standards for hearing aids with regard to recommended values of magnetic field strength for the use of induction pick-up coils [8] and also for electrical input levels to hearing aids [9]. The magnetic field strength values have also been implemented for fixed line telephones by the European Telecommunications Standards Institute (ETSI) [10] and the International Telecommunications Union (ITU-T) [11]. In addition ETSI has standardised requirements for electrical connection to hearing aids [14] and additional amplification for those who do not use hearing aids [15]. Consequently the interface for hearing aids and additional amplification is well established.
However no such standardisation or agreement appears to exist in Europe for mobile phones to recognise such interface values. In the USA thought the ANSI standard [7] there is recognition and a statement of requirement for EMC compatibility between hearing aids and mobile phones.
Clearly, any efforts to provide additional functionality on an auxiliary basis are going to be hampered by the non-standardisation of input/output ports on mobile phones. Whilst it is easily recognised that standardisation of such ports may result in the loss of revenue by manufacturers who wish to vigorously pursue the ancillary equipment market some financial gains must be apparent when a piece of equipment can be declared compliant for general interface to third party products. Of more importance is the consumer satisfaction that such facilities will bring.5.References
[1] Adrian Davis (1995 Hearing in Adults, Whurr Publishers Ltd, London
[2] Adrian Davis (2001) The prevalence of deafness and hearing impairment, Chapter 2 in Ballantyne’s Deafness: Sixth Edition. Editors John Graham & Mike Martin, Whurr Publishers, London
[3] Standard Rules for the for the Equalisation of Opportunities for Persons with Disabilities – UN Resolution
[4] COST 219 - Is anyone answering? (1990) Commission of the European Communities, Brussels
[5] HAMPIIS technical report TR1
[6] IEC 60118-13 1997 Hearing aids – Part 13: Electromagnetic compatibility (EMC). International Electrotechnical Commission, Geneva
[7] ANSI-PC63.19 [2002] American National Standard for Methods of Measurement of Compatibility between Wireless Communications Devices and Hearing Aids.
[8] IEC 60118-4 Hearing Aids – Part 4: Magnetic field strength in audio-frequency induction loops for hearing aid purposes. International Electrotechnical Commission, Geneva
[9] IEC 60118-6 Hearing aids Part 6: Specification for characteristics of electrical input circuits for hearing aids. International Electrotechnical Commission, Geneva
[10] ETSI ETS 300 381 Telephony for hearing impaired people; Inductive coupling of telephone earphones to hearing aids. European Telecommunication Standards Institute, Valbonne, France
[11] ITU-T P.370 Telephone Transmission Quality Subscribers’ Lines and Sets: Coupling hearing aids to telephone sets
[12] EHIMA (1995), EHIMA GSM Project Final Report - Hearing Aids and GSM Mobile Telephones: Interference problems, methods of measurement and levels of immunity. European Hearing Instrument Manufacturers Association, Brussels
[13] NAL (1995), Interference to Hearing Aids by the Digital Mobile Telephone System, Global System for Mobile Communications, (GSM). National Acoustics Laboratory Report No. 131, Sydney
[14] ETS 300 679 Telephony for hearing impaired people; Electrical coupling of telephone sets to hearing aids. European Telecommunication Standards Institute, Valbonne, France
[15] ETS 300 488 Telephony for hearing impaired people; Characteristics of telephone sets that provide additional receiving amplification for the benefit of hearing impaired users. European Telecommunication Standards Institute, Valbonne, France
[16] ETSI TR 102 068 Human factors (HF); Requirements for assistive technology devices in ICT. . European Telecommunication Standards Institute, Valbonne, FranceAnnex A
A.1 Measurement methods
In order to be able to quantify whether or not there is an interference problem it is necessary to be able to make repeatable and reliable measurements. The quantities to be measured are:
- The level of interference signals that are likely to cause the user varying degrees of difficulty when using the hearing aid in the presence of a mobile phone.
- The level of immunity of the hearing aid to specified types of signal over a defined frequency range
- The level of radiation from the mobile phone that is present at the hearing aid when it is being used in a normal manner.
In order to establish the levels of interference signals that are likely to cause a problem and to establish a measurement method subjective evaluations have been undertaken by the European Hearing Instrument Manufacturers Association (EHIMA) in 1995 [12], and by the National Acoustics Laboratory, Sydney, Australia also in 1995) [13]. These evaluations related the level of the interference signal to an equivalent acoustic input to the microphone of the hearing aid, now known as the Input Related Interference Level (IRIL). The level that was determined from the EHIMA study was 55 dB SPL, which represented a level of interference that was such that it did not significantly effect the perception of speech. It does not represent a zero level of interference. This level is then taken as the on that should not be exceeded if the user is to experience a satisfactory listening situation.
Given that there is a target value for IRIL there has to be an objective method of measuring the immunity of the hearing aid. This is achieved by placing the hearing aid in an appropriate RF field and measuring the acoustic output of the hearing aid. The gain of the hearing aid is also measured at the same time, with the same settings of the aid when in the RF field. The level of interference present at the output of the aid can then be equated to an equivalent acoustic input to the microphone by subtracting the value of the gain of the aid from the output signal and quoting it as the IRIL. The method of measurement was proposed in the EHIMA (1995) [12] study and has since been incorporated in the IEC 60118-13 standard, IEC (1997) [6].
The level of radiation from the mobile phone will obviously directly influence the level of interference in the hearing aid. A method of measurement of the level of radiation from a mobile phone relevant to hearing aid interference has been proposed by the American National Standards Institute (ANSI) and recently accepted as an American national standard. The standard, ANSI P63.19 (2001) [7], requires a matrix of measurements around the ear cap of the mobile phone, which effectively plots the level of field strength that may affect a hearing aid worn behind the ear when the mobile phone is used in the normal manner.
Consequently there has been available for some while agreed methods of measurement both of the immunity of hearing aids and the level of radiation from mobile phones. All major European manufacturers of hearing aids have been using the above methods of measuring immunity to improve the level of immunity of their products. Mobile phone manufacturers have not adopted the use of the ANSI method of specifying levels of radiation and consequently hearing aid users have no means of knowing which mobile phones have high levels of radiation relevant to interference problems and those that have low values.
The IEC 60118-13 (1997) [6] standard provided a means of measuring the immunity of hearing aids and also specified two scenarios in which levels of immunity were to be specified. These were the so-called “Bystander” and the “User” situation. The “Bystander” situation was where a hearing aid user might be close to a person using a mobile phone and receive an interfering signal. A signal strength of 3.5V/m was assigned to this situation for the agreed IRIL of 55 dB SPL. Consequently all new production hearing aids meet this requirement.
However the IEC 60118-13 [6] standard did not specify a value of field strength for the “User” situation but a proposed revision of this standard now gives a value of 75V/m.
The ANSI C63.19 [7] standard uses the same methods for measuring the acoustic output of the hearing aid under test but gives a set of rating values for both the immunity of the hearing aid and the radiation from the hearing aid. This in theory then allows hearing aids and mobile phones to be matched for immunity and radiation levels to give a user situation that is acceptable.
A.2 Test results
The methods of measuring immunity described by IEC and ANSI are very similar except for the method of generating the RF field. The IEC standard recommends the use of a GTEM cell whereas the ANSI standard proposes the use of a dipole. The problem that currently exists is that the correlation between these two types of measurement is not good and furthermore the correlation with user experience is not well documented. Currently work is being undertaken by EHIMA in conjunction with members of the ANSI committee to try and resolve these problems.
Both objective methods of measurement do not take into account the effect of the hearing aid being worn on a real head. It is understood that the further the aid is from the mobile phone antenna the lower the level of interfering signal. Consequently it is expected that hearing aids worn in the ear, in the ear canal and deep in the canal will be less affected by interference from the mobile phone.
Consequently there is a need to have better knowledge of the relationship between user experience and the objective measurements of immunity. Currently the best advice that can be given to a hearing aid user, in the absence of any data readily available to them, who wants to use a mobile phone in the normal manner, is to try various phones and see which one gives the least interference. Taking care, of course, that the phone is radiating at a level that is typical of its normal use in the user environment.Last updated: 20.05.2009 © Copyright reserved Website design: Digital Accessibility Team