In the 1930s, audio tech nerds were tinkering with everything. The most futuristic model homes of the day were wired for sound in every room, home audio recording was being introduced, and the LP was invented to use as audiobooks for the blind. And even things we’d consider mundane today got the radio treatment in order to make them high-tech. One of those things was the police line-up, seen above wired for sound in 1931.
Source: Gizmodo – This Was the Futuristic Police Line-Up of 1931