The brown part looks normal. The urate is quite yellow and if I am not wrong also quite brownish. Ideally it is white to light yellow.
From what I know, this could mean two things: Either he has retained poop for a longer time in which case it can occur that urate is more on the yellow side...
I don't think hearing them can cause stress, because Chameleons lack the outer ear and therefor only can 'hear' very low frequencies. I would say the main problem is mixing two different climatic zones together. Red eye tree frogs are from the wet tropics while veiled are from moist valleys...