{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,20]],"date-time":"2025-10-20T16:24:16Z","timestamp":1760977456271},"reference-count":34,"publisher":"Acoustical Society of America (ASA)","issue":"3","content-domain":{"domain":["pubs.aip.org"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2000,3,1]]},"abstract":"<jats:p>In clinical measurements of hearing sensitivity, a given earphone is assumed to produce essentially the same sound-pressure level in all ears. However, recent measurements [Voss et al., Ear and Hearing (in press)] show that with some middle-ear pathologies, ear-canal sound pressures can deviate by as much as 35 dB from the normal-ear value; the deviations depend on the earphone, the middle-ear pathology, and frequency. These pressure variations cause errors in the results of hearing tests. Models developed here identify acoustic mechanisms that cause pressure variations in certain pathological conditions. The models combine measurement-based Th\u00e9venin equivalents for insert and supra-aural earphones with lumped-element models for both the normal ear and ears with pathologies that alter the ear\u2019s impedance (mastoid bowl, tympanostomy tube, tympanic-membrane perforation, and a \u201chigh-impedance\u201d ear). Comparison of the earphones\u2019 Th\u00e9venin impedances to the ear\u2019s input impedance with these middle-ear conditions shows that neither class of earphone acts as an ideal pressure source; with some middle-ear pathologies, the ear\u2019s input impedance deviates substantially from normal and thereby causes abnormal ear-canal pressure levels. In general, for the three conditions that make the ear\u2019s impedance magnitude lower than normal, the model predicts a reduced ear-canal pressure (as much as 35 dB), with a greater pressure reduction with an insert earphone than with a supra-aural earphone. In contrast, the model predicts that ear-canal pressure levels increase only a few dB when the ear has an increased impedance magnitude; the compliance of the air\u2013space between the tympanic membrane and the earphone determines an upper limit on the effect of the middle-ear\u2019s impedance increase. Acoustic leaks at the earphone-to-ear connection can also cause uncontrolled pressure variations during hearing tests. From measurements at the supra-aural earphone-to-ear connection, we conclude that it is unusual for the connection between the earphone cushion and the pinna to seal effectively for frequencies below 250 Hz. The models developed here explain the measured pressure variations with several pathologic ears. Understanding these mechanisms should inform the design of more accurate audiometric systems which might include a microphone that monitors the ear-canal pressure and corrects deviations from normal.<\/jats:p>","DOI":"10.1121\/1.428440","type":"journal-article","created":{"date-parts":[[2002,7,26]],"date-time":"2002-07-26T14:08:13Z","timestamp":1027692493000},"page":"1548-1565","update-policy":"http:\/\/dx.doi.org\/10.1063\/aip-crossmark-policy-page","source":"Crossref","is-referenced-by-count":27,"title":["Acoustic mechanisms that determine the ear-canal sound pressures generated by earphones"],"prefix":"10.1121","volume":"107","author":[{"given":"Susan E.","family":"Voss","sequence":"first","affiliation":[{"name":"Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, Massachusetts\u200902114"},{"name":"Speech and Hearing Sciences Program, Harvard\u2013M.I.T. Division of Health Sciences and Technology, Cambridge, Massachusetts\u200902139"},{"name":"Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts\u200902139"},{"name":"Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, Massachusetts\u200902114"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"John J.","family":"Rosowski","sequence":"additional","affiliation":[{"name":"Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, Massachusetts\u200902114"},{"name":"Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, Massachusetts\u200902114"},{"name":"Department of Otology and Laryngology, Harvard Medical School, Speech and Hearing Sciences Program, Harvard\u2013M.I.T. Division of Health Sciences and Technology, Cambridge, Massachusetts\u200902139"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Christopher A.","family":"Shera","sequence":"additional","affiliation":[{"name":"Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, Massachusetts\u200902114"},{"name":"Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, Massachusetts\u200902114"},{"name":"Department of Otology and Laryngology, Harvard Medical School"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"William T.","family":"Peake","sequence":"additional","affiliation":[{"name":"Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, Massachusetts\u200902114"},{"name":"Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts\u200902139"},{"name":"Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts\u200902139"},{"name":"Speech and Hearing Sciences Program, Harvard\u2013M.I.T. 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