Hello! A lot of the background noises on that track were made by Jonny running his transistor radio through his pedalboard (as he does in live performance). The particular “sample” that you mention was likely created by sending a radio broadcast of someone talking through his DOD 440 Envelope Filter and BOSS SD1 Overdrive. The gain on the SD1 is probably at max. He seems to be adjusting the filter as the radio plays, and when the higher frequencies are accentuated (the 440 is a band pass filter) we can hear the extra high frequency noise that the SD1 brings out due to its high gain setting. A similar sound would be possible by just adjusting the gain on the SD1, but due to the lack of clarity in the vocals it sounds like the SD1 is always at max gain, and the 440 controls the frequency content.
Also, the part of the “sample” at 2:07 (and repeated at 2:16) sounds like it was looped in a DAW much like they probably did on Scatterbrain.