Did you read the full article? It sounds like you are misrepresenting the quote. It’s apparently industry standard to have the cinemas set their volume to valu

Did you read the full article? It sounds like you are misrepresenting the quote. It’s apparently industry standard to have the cinemas set their volume to value 7. The sound engineers then prepare the soundtrack with the expectation it will be set to 7. This particular theatre was set to 5.5 (perhaps to compensate for a previous movie that didn’t follow the standard and was mixed “too loud”), and hence the movie was significantly more quiet than the sound engineer intended.