What does the Acoustic Reflectance tell us about the middle ear? MEMRO 2009

1. What does the Acoustic Reflectance tell us about the middle ear?MEMRO 2009 Patricia Jeng, Pierre Parent, Jont Allen, Mimosa Acoustics Harry Levitt, Advanced Hearing

2. Goals Acoustic power measurements quantify wide band complex: • Reflectance • Transmittance • Immittance These measures provide clues to our puzzle: Resonance frequencies - Stiffness vs. mass dominance • Sites of reflection • Conductive hearing loss: mild, moderate, severe • Air-bone gap & Tympanometry Mimosa Acoustics, Inc. - MEMRO, 2009

3. Rigid cavity vs. B&K4157 Power reflectance Transmittance Reflectance phase Reflectance group delay (residual length) Impedance magnitude (Z) Normalized resistance - real(Z) – frictions of joints / energy dissipation Normalized reactance – imaginary(Z) – stiffness and masses Impedance phase = reactance / resistance +/- 90 degrees Mimosa Acoustics, Inc. - MEMRO, 2009

4. Adult: “Normal” (le) vs. OME (re) • Stiffness dominates • R - OME (blue) • AC: • 10, 20, 30, 25, 50 @ .25, .5, 1, 2, 4 kHz • BC: • -10,5, -10, 10, 15 • ABG: • 20, 15, 40, 15, 35 • Tymp: • NP daPa • 1.1 cc • NP mmho • L – normal (red) • AC: • 5, 5, -10, 0, -5 • BC: • 0, 5, -10, 5, 0 • ABG: • 5, 0, 0, -5, -5 • Tymp: • -20 daPa, • 1.2 cc, • 1.6 mmho Mimosa Acoustics, Inc. - MEMRO, 2009

5. Child – OM-no fluid • Stiffness dominate • Site of reflection • ABG • 66L & 66 R – both OME • Age: 7 year old • L ear • Tymp type: B • AC: 45, 45, 50, 40, 50 dB HL @ .25, .5, 1, 2, 4 kHz • BC: 5, 5, 5, 20, 25 dB HL • ABG: 40, 40, 45, 20, 25 dB • No fluid with retracted TM • R ear • Tymp type: B • AC: 45, 45, 50, 35, 50 dB HL @ .25, .5, 1, 2, 4 kHz • BC: 10, 0, 0, 20, 0 dB HL • ABG: 35, 45, 50, 15, 50 dB • Fluid - unacertain, with Rretracted TM 44 normal children ears Mimosa Acoustics, Inc. - MEMRO, 2009

6. Infant – passed OAE screen 44 normal children ears • Floppiness of the canal wall • Small volume • UU_395L_normal_day2 • Age: Day 2 • Moderate occlusion • Vernix / cerumen • Normal TM mobility • Effusion: uncertain Mimosa Acoustics, Inc. - MEMRO, 2009

7. Infant – failed OAE / obstructed canal • UU_395R_occluded • Age: Day 2 • Vernix / cerumen • Moderate occlusion • Normal TM mobility • Effusion: uncertain • Failed OAE screening on day 1, passed on day 2. Mimosa Acoustics, Inc. - MEMRO, 2009

8. Adult - Perforated TM & OM R ear - normal – blue • AC: 0, 10, 0, 0, 15, 5 • BC: -5, -10, -5, 15, 5 • ABG: 5, 10, -, 5, 0, 0 • Tymp: 5, 1.5, 0.5 • SRT/WR: 5, 100 L ear – acute otitis with drum rupture - red & pink • AC: 15, 10, 10, 15, 35, 45 • BC: 0, -5, -5, 5, 40, 30 • ABG: 15, 15, 15, 10, -5, 15 • Tymp: -85, 0.2, 0.2 • SRT/WR: 10, 100 Mimosa Acoustics, Inc. - MEMRO, 2009

9. Summary • The intention of this presentation is to show that all the measures obtained by the power measurements provide informative clues to the middle ear transmission status by identifying • the interrelations of the three impedance components (resistance, stiffness and mass); • the sites of reflections; • how much energy is transmitted to the middle ear structure; • how much acoustic energy is dissipated by the middle ear structure; • how much energy is transmitted to the cochlear; and • the relationship of audiometric air-bone gap and the transmittance expressed in log scale. Mimosa Acoustics, Inc. - MEMRO, 2009

10. Summary • The residual distance as computed from the reflectance group delay might be used to indicate the sites of reflections at low frequency. From the examples shown, the sites of reflections in the OME ear is at or close to the ear drum depending on the severity of the infection. In the normal ears, the sites of reflection are beyond TM. • In the OME ear, the middle ear structure is much simpler in its mechanical property giving much less complex reflectance group delay than in the normal. • Transmittance might provide as an objective and qualitative prediction of the audiometric air-bone gaps in screening and better identifying young children with OME who need follow up assistance. Mimosa Acoustics, Inc. - MEMRO, 2009

11. Data come from several projects • SBIR 6554 at Mimosa Acoustics • Patrick Feeney, University of Washington • Lisa Hunter, University of Utah • Gravelino Study – • Andrea Bohnert, Mainz, DE • Mimosa Acoustics • Kyle Rust • Elizabeth Allen Mimosa Acoustics, Inc. - MEMRO, 2009