By directly coupling to the test subject's ear canal via the disposable 3M™ E-A-RLINK™ Foam Eartips, the 3M™ E-A-RTONE™ 3A and 5A Insert Earphone offers audiometric testing that helps provide both performance and reliability advantages over traditional supra aural earphones. Some of these benefits include improved ambient noise attenuation, greater interaural attenuation, facilitated infection control (via disposable eartips), the elimination of collapsed canal artifact, better test/re-test reliability, and reduced occlusion effect for BC testing.