"Semi" is a recording of cicadas, made in late August in my garden. The summer had been especially hot, and the sound of cicadas in the trees was really overpowering at times.
From absolute silence, their sounds would suddenly emerge and escalate, before returning to silence again.
The recording is untreated, except for some filtering: the first few minutes have a high pass filter so that only the cicada sounds are allowed.
Gradually, over the course of the recording, I filtered in the rest of the lower frequencies, so the street ambiance slowly bleeds in and the full sonic picture comes into view. During the final seven minutes, the cicadas cease to be heard and only that street ambiance remain.