A tip for coupling sound between a medical instrument and an ear includes a sealing surface configured to substantially conform the tip to an auditory canal of the ear. The tip includes an acoustic tube acoustically coupled to at least one of the plurality of openings and defining a first acoustic path. The tip also includes a second acoustic path acoustically coupled to at least another one of the plurality of openings in the sealing surface. The acoustic tube of the first acoustic path is configured to substantially acoustically isolate the first acoustic path from the second acoustic path. A tympanometric instrument is configured to use the tip and to provide an acoustic measurement of the ear of a patient.