Although the term "gobo" can mean different things, to audio people, a gobo is a movable wall or divider to help isolate the sound of a particular individual or group of musicians or vocalists. This idea is a result of the close-miking techniques that were proposed by both Les Paul and Tom Dowd.
With acoustical recording that was invented by Edison in the 1870s, every record was a live recording done in a single take with one or more sound horns capturing the ensemble's sound in that room. When electrical recording became available in February of 1925, many "more traditional" engineers simply replaced the sound horn with a single microphone as continued to record basically the same way they always had done, using the ensemble sound of the room to create the mix.
However, some of the more progressive engineers started to use multiple microphones and place them in close proximity to certain instruments, so that where the musicians were located in the room became was less of a factor. Then, the music could be mixed, by using a console and controlling the gains of the mics.
In order to have more isolation or separation between the various mics, engineers started to use movable room dividers or gobos. Doing this helped to contain the sound of louder instruments, and also helped control the bleed (the unwanted off-mic sound from other instruments), and thus increased the presence of the entire recording.
![](https://i.ytimg.com/vi/shn9o4cdO2E/maxresdefault.jpg)