What is the audio file in Portal that plays when a radio is destroyed?
The disintegration sounds are in (for standard Windows configuration of Steam) C:\Program Files (x86)\Steam\steamapps\common\Portal\portal\portal_pak_dir.vpk.
This file has a bunch of folders with files used in Portal. I opened it in GCFScape and found that dinosaur_fizzle.wav, dinosaur_fizzle2.wav, and dinosaur_fizzle3.wav. As seen in this video these files were added along with the other radio-related audio to the 2010 update and play when the radio is "emancipated".
The three specific files are in this Google Drive folder I made.