 By the end of the 1970s, subwoofers were used in dance venue sound systems to enable the playing of "[b]ass-heavy dance music" that we "do not 'hear' with our ears but with our entire body".One challenge with getting deep sub-bass was that in the era of vinyl records, "to get as much music as possible on a record, recording engineers must limit the depth and excursion of record grooves.So in the recording process, the lower frequencies are often deliberately reduced or cut off altogether."