The familiar sound of a cough

I was just in the gents attending to important, routinal business and I heard a colleague cough in the neighbouring kitchen. I knew immediately who it was and it got me thinking - in our small company of 15 people I could identify unequivocally one of them just by the sound of their cough. Is this because I am familiar with their exact cough or does their accent/tone of voice come through with the cough? I am quite confident I could pick out the sound of my father coughing, for example, in a line-up of 50 people - why is this?