Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Not standing up to use in a school

I purchased a class set of the AC-201R headphones for my school. We are having trouble with one or both ear pieces not providing sound after about 1 month of use. They do get used about 5 hours/day but I did expect to get more than one month use out of them. I will look for a heavier duty headphone