Are you sure it is coming from the head lining?
It's just that there is a common problem with all 156's in time... I have had this problem on two of mine.
It sounds like a mix of someone has stuffed bubble wrap or eating a bowl of rice crispies in the car and it appears as if it is coming from just above your right ear is this correct?
Due to sound transference it took me a while to find it but it was the upper front and rear window seals... They go hard with age and start to rub against the metal of the door frame on the inside of the seal.
The solution I came up with was to slowly prise the seals out with the windows fully down.
Use insulating tape along the leading edge of the metal frames.
Spray the inner part of the rubber seals with 3 in 1 silicon lubricant spray.
After you have sprayed them, gently flex the seals back and forth to get them malliable again and refit back in position ... Job done
While you are at it do the same to the outer window seal that runs along the top of the door, not the frame... Just be careful not to twist it though, it has a thin metal strip that goes out of shape easily.
It used to be bloody annoying as the car was lovely and quite otherwise... I owned my first 156 a further two years without this noise coming back in that time. My latest 156 had the very same noise and issue... Did that right away 3 month ago... still hasn't returned