The first and most frequent features are

The necessity of having sentences repeated:
One misses words or whole sentences because they are misunderstood or confuses them in the conversation. A further reason can be that deeper sounds (electrical appliances, traffic…) are heard unduly loudly which makes comprehensibility of the language worse.

Difficulties during conversations:
If conversation with other people is affected by loud surrounding noise, it can lead to difficulties in understanding.

Problems in understanding speech:
For people who are hard of hearing, weakness at high pitch is much greater that at deep pitch. Therefore, high frequency consonants important for understanding of speech (e.g. C – S – F – Z) are often not understood in comparison with the low frequency vowels (e.g. A – E – I – O – U) .

Discomfort and stress: 
Difficulties in the understanding of words during a conversation make participation in social life difficult.

Difficulty in understanding children:
Children’s voices are generally higher in pitch and thus harder to understand.

Necessity of turning up the volume on the television or radio:
While your fellow humans think the walls are shaking, you think the volume of the television is just right-a sign that you must take seriously.