 Though Perry is anthropomorphic , he does not speak , only communicating through an " aggravated <unk> " type of noise made by flapping his bill . This noise is provided by actor Dee Bradley Baker ; to this day , Povenmire and Marsh do not understand how Baker produces the noise . Thomas <unk> , who plays Ferb , is notoriously good at making the noise and is considered second only to Baker himself . When in his " Agent P " persona , Perry is almost completely silent . 
