Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Drums in the Bedroom

This was a great disappointment. After reading reviews of other Vornado models and complaints about the loud knocking that periodically comes from air entering the water tanks, I decided to discount these complaints. After all, this is a new model and it is advertised as "bedroom quiet". I figured that the manufacturer had solved the problem. Wrong! The humidifier fan is actually very quiet but loud knocking woke us up repeatedly during the night. I would give this humidifier the highest 5-star rating for its use as a humidifier. However, since we cannot use it at night in the bedroom, its use is limited. We try to keep it on during the day and turn it off at bedtime. This is, otherwise, a first class humidifier. Why can't Vornado solve this problem?