Translation:We hear him playing the violin at night.
I don't understand where him is in this sentence. Is it the conjugated form of suonare?
Lo = "him" - lo sentiamo - "we heard him"
In the construction "hear/see sb doing sth", Italian evidently uses an infinitive - suonare where in English we use an "-ing form".
It would be easier to decipher the speech if "she" were not underwater when she spoke. I just spent 5 minutes on a previous question trying to detect if the voice said "gli piace" or "mi piace."