The conventional methods for diagnosing pathological conditions of the tympanic membrane (TM) and other abnormalities require measuring its motion to an acoustic excitation for its use in a clinical environment. To obtain comprehensive quantitative diagnostic information from the motion of the entire surface of the TM, it is necessary to devise an integrated system capable of accurately recording the motion and induce an acoustic stimulus. To accomplish this goal, a sound presentation system (SPS) capable of impinging acoustic stimulus in the frequency range of 20Hz to 8 kHz at known amplitudes is synthesized in this thesis. This system is then integrated with optoelectronic digital holographic system (OEDHO) which utilizes laser interferometry to record and reconstruct phase shifted images with the help of a digital camera. The OEDHO is capable of accurately recording nanometer scale motion of the TM. The preliminary design of the SPS depends on the physical dimensions of the human ear, such as the diameter of the TM (6-9mm), depth of the ear canal (about 30mm), and also dimensions of the OEDHO system such as: diameter of tip of the otoscope head for optical access (8mm), and possible locations for integration with the OEDHO. The characteristics of the system are based on the intensity of the acoustic stimulus necessary to vibrate the TM (90-110dB SPL), and method of impinging the stimulus. To accomplish this goal, the nature of sound wave propagation through a circular pipe with known dimensions is analyzed analytically, experimentally, and by using finite element analysis (FEA). The pipe is further investigated for optimum parameters using FEA by introducing changes in the diameter (3.8mm, 6mm, 10mm), length of the pipe (30mm, 60mm, 90mm), radius of the curvature (50mm, 75mm, 100mm), and strength of the sound power source (0.2W, 0.4W, 0.6W). The comparative results provide guidelines for the design of the first version of the SPS (SPS_V1). The SPS_V1 consists of a symmetric design to impinge the acoustic stimulus towards the TM and a microphone to measure the sound pressure at the TM. The system is capable of housing a range of speakers from 2mm to 15mm in diameter. The SPS_V1 can directly interface with the standard medical speculums used for human ear testing. Also, the system is capable of interfacing with all available versions of the OEDHO. The SPS_V1 is currently being evaluated in a medical-research environment to address basic otological questions regarding TM function. The performance characterization of the system inside an artificial ear canal with two different speaker configurations is herein shown, and the potential improvements and utilization are discussed

Thesis (M.S.)--University of Michigan, 1995.

Thesis (M.S.)--University of Michigan, 1995.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2010.

The hearing process involves a series of physical events in which acoustic waves in the outer ear are transduced into acousto-mechanical motions of the middle ear, and then into chemo-electro-mechanical reactions of the inner ear sensors that are interpreted by the brain. Air in the ear canal has low mechanical impedance, whereas the mechanical impedance at the center of the eardrum, the umbo, is high. The eardrum or Tympanic Membrane (TM) must act as a transformer between these two impedances; otherwise, most of the energy will be reflected rather than transmitted. The acousto-mechanical transformer behavior of the TM is determined by its geometry, internal fibrous structure, and mechanical properties. Therefore, full-field-of-view techniques are required to quantify shape, sound-induced displacements, and mechanical properties of the TM. Shapes of the mammalian TMs are in millimeter ranges, whereas their acoustically-induced motions are in nanometer ranges, therefore, a clinically-applicable system with a measuring range spanning six orders of magnitude needs to be realized. In this Dissertation, several full-field measuring modalities are developed, to incrementally address the questions regarding the geometry, kinematics, and dynamics of the sound-induced energy transfer through the mammalian TMs. First, a digital holographic system with a measuring range spanning several orders of magnitude is developed and shape and 1D sound-induced motions of the TM are measured with dual-wavelength holographic contouring and single sensitivity vector holographic interferometry, respectively. The sound-induced motions of the TMs are hypothesized to be similar to those of thin-shells (with negligible tangential motions) and therefore, 3D sound-induced motions of the TM are estimated by combining measurements of shape and 1D motions. In order to test the applicability of the thin-shell hypothesis, and to obtain further details of complex spatio-temporal response of the TMs, holographic systems with multiple illumination directions are developed and shape and acoustically-induced vibrational patterns of the TMs are quantified in full 3D. Furthermore, to move toward clinical applications and in-vivo measurements, high-speed single-shot multiplexing holographic system are developed and 3D sound-induced motions of the TM are measured simultaneously in one single frame of the camera. Finally, MEMS-based high-resolution force sensing capabilities are integrated with holographic measurements to relate the kinematics and dynamics of the acousto-mechanical energy transfer in the hearing processes. The accuracy and repeatability of the measuring systems are tested and verified using artificial samples with geometries similar to those of human TMs. The systems are then used to measure shape, 3D sound-induced motions, and forces of chinchilla and human cadaveric TM samples at different tonal frequencies (ranging from 400 Hz to 15 kHz) simultaneously at more than 1 million points on its surface. A general conclusion is that the tangential motions are significantly (8-20 dB) smaller than the motions perpendicular to the TM plane, which is consistent with the thin-shell hypothesis of the TM. Force measurements reveal that frequency-dependent forces of the TM, are also spatially dependent so that the maximum magnitudes of the force transfer function of the umbo occurs at frequencies between 1.6 to 2.3 kHz, whereas the maximum values for other points on the TM surface occurs at higher frequency ranges (4.8 to 6.5 kHz). The Dissertation is divided into two Parts, each contains several Chapters. In the first Part, general overviews of the physiology of the human middle ear, along with brief summaries of previous studies are given, and basics of holographic interferometry are described. In the second Part, developments and implementations achieved in completion of this work are described in the form of a series of manuscripts. Finally, conclusions and recommendations for future work are provided.

In this thesis work, we develop an optoelectronic holographic platform to facilitate otologists' ability to quantitatively study and diagnose disorders of the tympanic membrane (TM) and middle ear of humans in full-field-of-view. The holographic platform consists of a laser delivery system, a handheld interferometer, and corresponding software, which allow nanometer scale 3D measurements of deformations of the TM.

Diss. (sammanfattning) Linköping : Linköpings universitet, 2008. / Härtill 4 uppsatser.

Diss. (sammanfattning) Umeå : Univ., 2007. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2002. / Härtill 6 uppsatser.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 4 uppsatser.