omer

Question

First of all I wanted to thank the entire Abadi family for with wonderful website. I recently read on one of the Q&A threads that it is permissible to play and listen to music on the omer. I have been brought up my whole life that this was not allowed. I was just wondering where people got the got the notion that it is against halacha to do so. Also, since a lot of what I thought was not allowed to be done is allowed, can you tell me what in fact are the prohibitions for the omer