No matter where you usuallyhear today's top hits—the radio, Spotify, amixtape on your Sony Walkman — you've probably noticedthat they tend (be) around three minutes long.
As VOX — a classic record company — explains, the custom (date) back to the early 20th century, whenshellac records (虫胶唱片) first appeared in themarket. The rates at these records spun (旋转) varied, but 78 RPM (每分钟转数) quickly became the norm. Tworecord sizes contributed to its (popular): 10 inches — which could hold about three minutes of music per side—and 12 inches, which held (rough) four to five minutes per side. To getradio stations to broadcast their music and get people to buy it, (musician) pretty much had to accommodatethose time limits.
The late 1940s (see) the birth of the 45 RPM record: asmaller, cheaper disc that couldn't manage much more three minutes of music per side. Long-playingrecords (LPs) (introduce) around the same time, but it wasmuch easier for radio stations to play single tracks from 45 RPM record — whichcrowds of listeners then went out and bought. While 10-inch 78 RPM record hadoriginated the three-minute trend, 45 RPM record really helped make a necessity for radio singles throughout themid-20th century.
