Googling showed a previous thread and robust intervention by Tightslot so I will tread warily . I was in a bit of a grump anyway as I don't care for sleeping fully clothed. However it did strike me as a design shortfall. All well and good to ply me with linen table cloths, glass to drink from and other geegaws but no real sense of quality in a fundamentally uncomfortable environment. If air change volume equals area times speed of flow then perhaps more duct area and less airflow speed? I wonder if cc don't end up with hearing issues if they are exposed to that din all the time.