By its very nature, hearing loss results in selective hearing. People with hearing loss have to pay attention and expend a lot of effort when listening. And nobody can pay attention 100% of the time. So the person with hearing loss has to “select” when to hear.
Hearing loss is also selective in that we hear better in some situations than others. We hear better when: we are alert and focused; we are sitting close to the person who is speaking; when we can see the person we are talking to; and myriad of other variables.
Living with hearing loss myself, here are examples of times when I might not “choose” to pay attention: when I am tired; when the listening environment is challenging, such as at a noisy family gathering; when the person speaking is difficult to understand; when the conversation does not interest me (and therefore the ‘cost’ in terms of effort is higher than the perceived benefit).
Tips are in a related post.