My wife often complained about the noise from ours, so I just went to the loo earlier in the day before she went to bed
But now ours is bust (I'm leaving it for 12 months in the hope that it may forget it was broke & work again
).
You could box it & put 50mm Kingspan etc inside the boxing. Remembering to leave plenty of room for airflow and to ensure that the boxing is removable for maintenance (and with a moderator - this is a high possibility).
Depends if you have room for a box & are not bothered about seeing a box compared to putting up with the noise.