BACKGROUND ear canal narrowing is the thinning or closing of the ear canal. This can damage the sound transmition from the external to the internal ear, which in turn may cause a false hearing loss. OBJECTIVE to alert the professionals of the area on how to avoid a miss diagnosis. METHODS a 47 year old woman, submitted to two audiologic evaluations: one without avoiding ear canal closing and one avoiding it. RESULTS a decrease of up to 40 dB was observed in the results of the second evaluation. CONCLUSIONS in order to obtain reliable results it is extremely important to verify the presence of ear canal narrowing, at any age, and to use appropriate procedures to avoid it from happening during testing.