In the culture of electro-magnetic compatibility this argument has validity, for the defined immunity levels tend to assume that there is some separation between potentially interfering devices. In fact, this argument remains valid until the user of a hearing aid wishes to use a mobile phone and then, not unreasonably, also wishes to listen to it through the hearing aid. This obvious situation has not been foreseen in the drafting of the relevant standards and the unavoidable conclusion is that interference problems will continue to arise unless and until the standards are amended. Technical answers to the problem are available, but will not be universally adopted until it is possible to prove that a piece of equipment is breaching EMC or other requirements, using a standard as evidence. If the mobile phone is performing as it should, and its emitted radiation is within the spectrum management limits, it might seem that it is the hearing aid which is at fault when interference is experienced.
Mobile phones emit radiation by design, whereas hearing aids receive it by accident.
The practical problem is of course that it is not easy to build in immunity in a product as small as a hearing aid. Some forms of radiation are more intrusive than others, so one solution might be to draft the spectrum management rules so as to prohibit the more troublesome modes. Another solution could be to adopt a definition of 'normal environment' for EMC purposes which assumed the use of a 'hands free' kit or some other form of coupling which distanced the hearing aid from the phone. A third option would be to acknowledge that the normal environment in an age of mobile personal communication will inevitably embrace significant levels of radiation across various frequency bands and transmission modes, with the result that immunity levels need to be raised. The real issue at the present would not seem to be that of which of the available solutions should be adopted, but rather the question of which body is competent to consider the matter and determine the answer.