Implications of Standardisation in Telecommunications
for Hard of Hearing People
M.C. Martin
The Mike Martin Consultancy,
Gerrards
Hill House Hill, Liphook
Hants GU30 7PX,
UK
Introduction
Some ten years ago it would be easy to describe the extent of
telecommunications and what were the implications of standardisation.
Today it is difficult to say where telecommunications begins
and ends. The reason for this is that the introduction of new
technology which includes digital systems, cable and radio services
all interface with the basic telephone system. With these new
systems and services has come the blurring of the distinctions
as to what are telecommunications and what are for instance broadcast
entertainment services. In this paper basic voice telephony,
which can be thought of as the conventional telephone, will be
given priority as it is the main reason why people with hearing
impairment are today often deprived of a means of communication
enjoyed by the majority of the population.
Today the basic telephone is installed in some 90% of all
homes in the majority of western countries. Our dependence on
the telephone grows with the trend for more services to be offered
through the telephone. Therefore any barrier to the use of the
telephone is a barrier to an individual's independence and the
effects of these barriers on a person's work and social life
as well as their general well being and safety have to be considered.
The degree to which these barriers can be reduced are very dependent
in the telecommunications field on the availability of appropriate
standards. The reason for this is that the telephone network
relies heavily on having a well regulated system right from the
input from the terminal on one end of the line to the output
from the terminal at the other end. Without this regulation users
would not be able to pick up the phone and get through to another
person, almost anywhere in the world, without a second thought
to what is happening. In other words the telephone system is
completely transparent to the users. This transparency is only
possible because of the widespread use of standards that all
telecoms service providers adhere to.
Hearing loss and telephones
While it is possible for people with no experience of hearing
loss to easily understand that a person with no hearing cannot
use the telephone because they do not hear what is being said,
it is difficult for them to understand the problems of those
with a less than total hearing loss. Furthermore it is often
difficult for the professionals involved in telecommunications
to understand the problem because there is a tendency to describe
hearing loss in terms of the levels found on an audiogram, i.e.
in decibels, rather than in functional terms.
From the point of view of the hard of hearing user the two
main important functional factors are - is the sound loud enough
to be heard comfortably and can the speech be understood. The
number of decibels of hearing loss is not the most important
factor and in fact does not always relate well to the ability
to hear speech over the telephone. However the table below gives
some approximations to the relation between decibels of hearing
loss, the ability to use the telephone and the proportion of
the adult population who have the problems.
Table 1. Average hearing loss,
the degree of difficulty in using
the telephone and the percentage of the adult population
having that degree of loss. Data based on information from Davis,A
(1995).
|
Average Hearing loss |
Degree of problem |
% of population |
|
10 dB |
None |
72 |
|
20 dB |
None/Little |
19 |
|
30 dB |
Moderate |
4 |
|
60 dB |
Great |
1.5 |
|
80 dB+ |
Near impossible |
0.5 |
The other factor which can be of equal importance is that
of being able to hear the phone ring. Even with a hearing aid
it is often not possible to hear the phone ring when the listener
is at a distance from the phone or there is noise in the surrounding
area.
A further factor which is often overlooked is that of losing
visual contact with the person speaking. Consequently while a
hearing impaired person may cope very well in a face to face
situation, due to the loss of lipreading and facial and body
language clues, they may be completely lost in following the
conversation over the telephone, particularly if it is with an
unknown person and if it involves names and unusual subject matter.
The environment in which the telephone is being used can play
an important part in determining if the conversation can be understood
or not and the effect of high levels of noise on a person trying
to use a hearing aid with the telephone can be disastrous. It
is often forgotten that the effects of background noise are far
greater on a person with a sensorineural hearing loss than a
person with normal hearing.
Finally it must be remembered that the majority of people
with hearing loss are over the age of sixty and with increasing
age comes an increase in other disabilities particularly declining
vision. These additional disabilities, no matter how small, all
add to the problems of using the telephone particularly as more
and more modern telephones rely on visual displays for a number
of services.
All of the above should be bore in mind if standards are going
to be produced which will allow the maximum number of people
to use the telephone.
Using the telephone
The steps we take to use the telephone are perhaps best illustrated
by the matrix in Fig. 1 taken
from the COST 219 publication "Telecommunications the Missing
Links". This matrix also identifies the degree of difficulty
and whether or not technology is available to alleviate the problem
across a wide range of disabilities. It will be seen that there
is potentially a great deal of technology that could be used
to overcome the problems, however much of this technology requires
standardisation to ensure its effective use.
For many hard of hearing people the main technology will be
that of providing a means of obtaining amplification. This may
be achieved by providing amplification built in or attached to
the telephone handset, by using a hearing aid directly with the
telephone (acoustic coupling), by inductive coupling with a hearing
aid or by a direct electrical connection to a hearing aid.
For those who cannot understand speech over the telephone
the use of a text telephone may be the only answer. However it
must be remembered that for some people it is a combination of
all the technology that may be the answer. There is no one answer
for everyone which makes the production of standards more difficult
in avoiding excluding some people while trying to include the
majority.
Standardisation
Given the range of possibilities above it might be thought
that there would be one body who would deal with all these matters
to ensure that the needs of hard of hearing people are dealt
with in an efficient manner. Table 2 below shows the main standardisation
organisations that are relevant to telecommunications and hard
of hearing people, these are in turn reflected in national committees.
This indicates the complexity of trying to follow all standards
development that is relevant to hard of hearing people.
Regional Directives
Standards produced by the organisations above are often used
by manufacturers to show conformity with Directives or national
regulations. In Europe Directives are produced by the European
Commission and have within them "Essential Requirements"
that have to be met by the manufacturers in order to obtain a
CE mark which then permits their products to be sold throughout
Europe. To show conformity with the "Essential Requirements"
manufacturers may use appropriate standards produced by a recognised
standards body such as CEN or CENELEC. In turn CEN and CENELEC
will use IEC or ISO standards wherever possible. The importance
of standards is therefore magnified by their being used to support
legislation and regulation as well as being arbiters of quality.
A further aspect of this is that if the Directives are not
worded to include the needs of hard of hearing people, indeed
they may even unintentionally exclude them by not making mandatory
provisions such as induction coupling. Consequently there is
a need for organisations of hearing impaired people to keep a
close watch on the telecommunications legislation and regulation
that is being produced. However the speed at which this legislation
is being currently produced makes this a very difficult task.
Time scales and process
One major problem with standards is the time that it takes
to produce them. Fig.
2 shows the process and the ideal time scale for producing
a standard in IEC or ISO. It can be seen that the time taken
is over three years and this is dependent on there being no setbacks
in the process. Consequently people have to be very sure that
there is a need for the standard, that the knowledge is available
to produce the standard and that if produced people will use
it.
Involving Hard of Hearing People in the Standardisation
Process
As standards are so important for the implementation of new
equipment and services in the telecommunications field the needs
of hearing people have to be reflected in these standards. However
if these needs are to be properly reflected the end user must
be involved in a meaningful way. This involvement requires the
availability from hard of hearing organisations of resources
both in terms of technical expertise and finance. Fig.
3 is a model produced by the Danish Centre and published
in their pamphlet "Good standards from the start".
However this model still requires the availability of people
with expertise and the financial resources to support active
participation in the standardisation process. In the UK a good
model for involvement is that of Hearing Concern, formerly the
British Association of the Hard of Hearing, who have a Telecommunications
Committee whose members are mainly hard of hearing people who
are engineers or who have been involved in the telecommunications
industry for many years. This committee has formed many valuable
political links which allow it to pursue the technical problems
into the political arena where they can influence policy decisions
by providing concrete technical information. Today policy decisions
made by governments and telecommunication regulators will determine,
more than anything else, whether or not facilities and services
for hard of hearing people will ever be available.
Current Standards
The numbers of standards which directly relate to the needs
of hard of hearing people are quite small in number and will
be discussed below. However in todays multi media world the problem
is to be aware of standards which in the first instance do not
appear to have any relevance. A prime example of this is the
standardisation of the GSM mobile telephone network which has
caused so much concern to hearing aid users but where those who
are concerned with the use of hearing aids were not considered
at the outset.
There exists a considerable number of standards relating to
the measurement of the performance of hearing aids contained
in the IEC 118 Hearing Aids series which has 13 parts. The relevance
of these to telecommunications has not been very apparent in
the past. However with the widespread use of inductive coupling
of hearing aids to telephones and the potential for directly
connecting the telephone to a hearing aid there has been a considerable
increase in activity in this area.
Currently IEC 118 Part 4 defines the magnetic field strength
required for the satisfactory function of room inductive loops.
IEC 118 Part 1 describes the method f measurement of the performance
of hearing aids using a pick up coil, the T switch position.
However these two standards do not relate to the use of the hearing
aid with a telephone and current work in IEC Technical Committee
29, Working Group 13 Hearing Aids, is producing ways in which
the use of the telephone with a hearing aid can be measured and
specified.
IEC 118 Part 6 describes the sensitivity of an electrical
input socket on the hearing aid which today is largely used for
the connection of FM radio receivers used in the education of
deaf children. The revision of this standard is prompted by the
work on standardisation of electrical output sockets from telephone
handsets and the need to ensure that the telephone and the hearing
aid have a clearly stated means of connection. The implications
of this work are quite considerable in that in due course it
could remove the current wide range of connectors that have to
be produced to match a hearing aid to an external device to perhaps
one or two designs.
The above work has been prompted by the developments with
ETSI who have produced a set of standards under a series with
an overall title of "Terminal Equipment (TE), Telephony
for the Hearing Impaired". Three standards have been produced
under this heading as follows:
ETS 300 381. Inductive coupling of telephone
earphones to hearing aids. Performance requirements and testing
methods.
ETS 300 488. Characteristics of telephone sets
that provide additional receiving amplification for the benefit
of hearing impaired.
Draft prETS 300 679. Electrical coupling of
telephone sets to hearing aids.
ETS 300 381 is very important for those people who find inductive
coupling on the telephone of great value. It aims to ensure that
if a telephone is marked as being "Hearing Aid Compatible"
that the telephone provides sufficient magnetic field to allow
the user to hear comfortably without having to use maximum amplification
on the aid. However this standard is an example of the lack of
input from both the users of hearing aids and the hearing aid
manufacturing industry, a situation which we hope will not arise
again. The standard gives two field strengths which are described
as "Preferred Range" and "Acceptable Range",
the latter being, in the opinion of some people, too low to give
a satisfactory connection for many hearing aid users. The acceptance
of the lower level comes about because that is the performance
that many telephones can produce. It is also due to the fact
that there was insufficient work undertaken and interest shown
by organisations for hearing impaired people to establish the
relevance of the levels proposed. This highlights the need for
more active participation and allocation of resources by organisations
in the standardisation arena. If you are not willing to play
and pay you cannot expect to influence the outcome. The current
result of this is that whereas the standard should ensure a hearing
aid user that they can use induction coupling on a telephone,
marked as being suitable for them, it cannot be guaranteed that
they can. Additionally the lack of standardisation of hearing
aid induction input sensitivity has compounded this situation.
ETS 300 488 on amplification built into the handset of the
telephone has come about by pressure from consumer representatives
and largely due to the involvement of the OFTEL Working Group
for the Hearing Impaired, now no longer supported by OFTEL, who
overcame the technical objections from telephone authorities
that they could not allow amplified telephones to be used because
they did not meet the test criteria set down for non-amplified
telephones. This is an example of standards and regulations preventing
the use of a device. The standard now gives methods of test and
allows up to 20 dB of amplification which will prove of great
value to those who do not use a hearing aid but have a moderate
to severe hearing loss. It is of interest to note that there
is a rule of thumb in audiology which states that the level of
amplification required by a hearing aid user is about half the
level of hearing loss. Therefore 20 dB of amplification in a
telephone will benefit a person with a 40 dB hearing loss. However
the telephone is itself a hearing aid as it gives effectively
some 30 dB gain over listening to someone speaking at a distance
of 1 metre. Consequently an amplified telephone meeting the ETSI
standard will probably be useful to a person having a 70 dB hearing
loss.
While the problem of interference from GSM telephones has
been closely looked at, EHIMA (1995), and solutions to the problem
of interference from someone using a GSM phone near a hearing
aid user have largely been solved on new aids being currently
produced, the problem of a hearing aid user wanting to use a
GSM phone is still largely unresolved. IEC 118 Part 13 Electromagnetic
Compatibility (EMC) Product Standard for Hearing Aids gives a
specification of the level of immunity from interference that
hearing aids should have and the methods of measuring this. It
does not give requirements for hearing aids used with a GSM phone
as insufficient knowledge is currently available to solve this
problem. However consideration of standards regarding the development
of GSM phones have offered some solutions. The availability of
"hands free" kits for GSM phones allows the transmitting
part of the phone to be removed from the proximity of the hearing
aid and by direct electrical connection or inductive coupling
the phone can then be used by the hearing aid wearer. Discussions
with the ETSI group responsible for standardisation of future
GSM services will hopefully produce standard interconnections.
However this area of interference from GSM mobile phones is one
where there is a need for greater involvement of hearing aid
users to provide factual evidence of the level of problems caused
by the widespread use of GSM phones. Currently there is little
evidence that there are any significant number of cases of interference
to hearing aid users from other people using GSM phones. Hard
of hearing organisations could play a useful role in collecting
such data which currently does not exist.
The development of standards for radio based data systems
e.g. Radio Local Area Networks, using transmissions similar to
GSM are well advanced and the potential for these systems to
create further problems, particularly in the work place, need
to be addressed now. The question is who is going to do this.
While the majority of hard of hearing people will be able
to use the telephone with amplification there are still a considerable
number of people whose hearing loss is such that they will need
the extra support of a text phone. The text phone allows the
use of the telephone and today through the availability of relay
services the user can speak directly to anyone anywhere in the
world. The development of text phones has been seriously delayed
by the lack of international standards which has meant that national
solutions have appeared but not international ones. However in
the last few years there has been a concentrated effort in Europe
to resolve this problem. The ITU has now produced a draft standard
V18 which in principle should provide a long term solution to
the problem and allow text phones to be as transparent as ordinary
telephones. However there has been relatively speaking very little
effort put into confirming that this standard will work in practice.
This reflects another problem with standards when there are no
commercial companies willing to provide the input into making
the standard work and manufacturing equipment to the specification.
Conclusion
The telephone is a major means of communication in the world
today and the inability to use the phone denies people access
to a wide range of normal contacts. Hearing impairment is a major
barrier to using the telephone and standardisation is one way
in which this barrier can be reduced.
A wide range of standards can affect the ability of hard of
hearing people to use the telephone. The development of these
standards has in the past had very little direct input from a
wide range of hard of hearing consumers. There are exceptions
to this and those groups of people have made a considerable contribution
to what has been achieved. However organisations at both national
and international level need to evaluate their role in the consideration
of telecommunications and their active participation, particularly
with regard to standardisation. The telecommunications networks
of the world work because of the high degree of standardisation
involved. If access to the telephone networks of the world is
to be as easy for hard of hearing people as for everyone else
then one way of achieving this is through ensuring appropriate
standardisation. This in turn requires dedication, expertise
and financing and for organisations to give a high priority to
this area if they want to see their members achieve the benefits
that telecommunications technology can offer.
