Hearing can play an important and useful part of using ICT. Whilst applications are largely visually driven as regards user interaction, there are many audio driven elements which can enhance the user experience, and in the initial stages of developing ict skills, tutorials, both classroom based and online are generally focused as much around audio information as they are visual. This is not to say that people with a total lack of hearing ability can't learn, use and enjoy ICT, but where the user has partial impairment, attention must be paid to improving this experience as much as possible, and with a little thought and limited resources, big improvements can be achieved for partially hearing impaired users. 
What is hearing impairment?
People can suffer from different types of partial hearing impairment ranging from the use of one ear only, to low levels of audible sensory in both or one ear, the reduction in ability to hear specific frequencies, and the common problem of tinnitus (ringing in the ears and usually compounded with a lack of ability to focus their hearing on a subject in the presence of background noise) . Following are a few simple suggestions and solutions.
Partial or total deafness in one ear:
The solution to this is simple and logical... In the instance of teaching, the user sits in a position where the functioning ear is directed towards the teacher.  If the audio level is still difficult to hear, then the teacher can use a a simple address system, such as a microphone and speaker, but operating this at a level which is not distracting or uncomfortable to other leathers in the same environment. The hearing impaired learner can also sit in closer proximity to this sound source to allow the to set at a level which fits their need and at the time doesn't adversely affect other learners.
Reduced function of both ears:
If the lerner doesnt use personal hearing aids or thre is no access to an induction loop, in ear headphones can be used to increase the level of the audio so the learner can hear the sound source more easily. This assists the user directly, without causing unnecessary loud volume in an 'ambient' way which may be distracting or indeed uncomfortable for other learners in the same environment. 
Ringing in the ears can become worse after exposure to loud sound sources, so use of address systems is not suitable for tinnitus sufferers. The issues around tinnitus are generally symptomatic of overloading the ears, and the ears reacting adversely, or not being able to process this information, so introducing loud sound sources can actually be counter productive. Loud sound sources can also exacerbate the ringing in the ears for the user for several days afterwards.  For tinnitus sufferers, its also important to reduce any other unnecessary background sounds as the mix of different audio information makes it difficult for the sufferer to filter out the required sound source. The solution is to use closed back headphones at a comfortably low volume as the closed back design automatically deadens ambient background noise and at the same time introduces the required sound source directly and closely into the ear, and because of this, it can also be reasonable quiet enough to hear clearly whilst not aggrevating the hearing condition.
Of course, any of the above solutions can be combined or experimented with in each individuals case. There is no solid rule... This is simply about improving the overall experience for the user and if something works for them, then that's the main objective. Soft touch solutions can also work, so in the case of a teacher not adressing a full class, then simply standing in closer proximity to a learner may suffice (which is common practice when teaching ICT as direct demonstration one workstation is usually required at some point) and indeed, the onus should always be on not causing unnecessary ebarassment to the learner, so these kind of simple and logical solutions can sometimes work best. The above are just basic, logical suggestions for a teacher to be able to establish a 'starting point' from which to think about possible solutions which may help partially hearing impaired learners of ICT subjects