As peas @greenpea said, if they have a history of drug or alcohol use they have to completely detox for a significant period of time before an accurate diagnosis can be made, because the symptoms of withdrawal from SAD can mimic MI @StarZee
That said, auditory hallucinations appear to freak shrinks out in this country and Australia shows itself to be the ignorant colony at the butt end of the world and light years behind the UK and parts of the USA in dealing with them. They tend to jump to the conclusion of a psychotic illness. AH were featured on SBS on Insight last year or the year before......it is not uncommon if a person has had trauma, especially sexual trauma. A book that resonated with me in terms of the degree of child abuse I was subjected to was Dr Bruce Perry's The Boy Who Was Raised As A Dog....he's written about AH in traumatised populations and you don't feel so freaked out by them if you read his research.
Corny