Fast and reliable The AT235 / AT235h is an automatic middle ear analyzer ideal for diagnostic and screening evaluations. It is an instrument providing top performance and user reliability with features in both screening and diagnostic applications. The AT235h holds new manual pump function allowing you to override automatic features and giving you control over pressure changes during tympanometry. The AT235h features two tests of eustachian tube function, one for perforated and one for intact eardrums as well as high frequency probe tones.