I live on a new estate built next to an old building which has numerous room it rents out to businesses. Aproximately five to seven bands hire rooms in the building and practice playing until 2300 hours every night. The music is so loud that we can not have windows open on warm evenings as despite being some 250 metres away its like they are in the living room with us. We have spoken to the owner and the council who in the last year have done very little. I have visited the building and seen the rooms which have no sound proofing and when warm windows are opened adding to the problem.
If it happens most nights and is loud enough, this could easily be enforced upon within a few weeks. You need to complete diary sheets, return them and call them out to witness the problem. The person responsible for the nuisance is liable in such cases but I would suggest that is the person/owner/entity hiring out the rooms (the person responsible is that whom the nuisance is attributable to – by their act but by default or sufference). As a commercial entity (contrary to the case with residential premises) one of the tests is whether they have taken best practicable means for reducing or abating the nusiance. That sounds very unlikely in this case if there no is sound insulation. I can only suggest being persistent with your environmental health service and, if that fails, going through the complaints procedures.