Aulis Telle

Sonotubometry with perfect sequences: First results in pathological ears

Abstract Conclusion: Sonotubometry with perfect sequences (PSEQ) was able to detect eustachian tube (ET) openings in both normal and pathological ears. Impaired ears showed ET openings in almost all cases; however, these proved to be not only less frequent, but also with lower amplitude and shorter duration. Objectives: To investigate the function of impaired ET under physiological conditions, using a novel kind of sound stimulus for sonotubometry – the PSEQ. Methods: Twenty otologically healthy subjects (40 normal ears) and 32 patients with ear diseases (40 pathological ears) were examined sonotubometrically using noise signals with an ideally flat spectrum (PSEQ). Dry swallowing, water swallowing, and Toynbee maneuver were used to induce ET openings. Analysis was performed regarding the frequency of occurrence, duration, amplitude, and form of the ET openings. Results: PSEQ allowed the detection of an ET opening in all 40 normal ears (91% of the performed maneuvers) and in 87.5% of the ears with impaired ET function (but only 47% of the maneuvers). The average amplitude of the openings in healthy ears was 16.86 dB, the average duration was 363 ms. In diseased ears these values were significantly lower: 9.73 dB, p < 0.001 and 280 ms, p < 0.05.

Perfect-sweep NLMS for time-variant acoustic system identification

Fast and robust acoustic system identification is still a research topic of interest, because of the typically time-variant nature of acoustic systems and the natural performance limitation of electroacoustic measurement equipment. In this paper, we propose NLMS-type adaptive identification with perfect-sweep excitation. The perfect-sweep is derived from the more general class of perfect sequences and, thus, it inherits periodicity and especially the desired decorrelation property known from perfect sequences. Moreover, the perfect-sweep shows the desirable characteristics of swept sine signals regarding the immunity against non-linear loudspeaker distortions. On this basis, we first demonstrate the fast tracking ability of the perfect-sweep NLMS algorithm via computer generated simulation of a time-variant acoustic system. Then, the robustness of the perfect-sweep NLMS algorithm against non-linear characteristics of real measurements in a time-invariant case is presented. By finally addressing the measurement of quasi-continuous head-related impulse responses, we face the combined challenge of time-variant and possibly non-linear distorted acoustic system identification in a real application scenario and we can demonstrate the superiority of the perfect-sweep NLMS algorithm.

First Steps into Practical Engineering for Freshman Students Using MATLAB and LEGO Mindstorms Robots

Besides lectures on basic theoretical topics, contemporary teaching and learning concepts for first semester students give more and more consideration to practically motivated courses. In this context, a new first-year introductory course in practical engineering has been established in the first semester curriculum of Electrical Engineering at RWTH Aachen University, Germany. Based on a threefold learning concept, programming skills in MATLAB are taught to 309 students within a full-time block course laboratory. The students are encouraged to transfer known mathematical basics to program algorithms and real-world applications performed by 100 LEGO Mindstorms robots. A new MATLAB toolbox and twofold project tasks have been developed for this purpose by a small team of supervisors. The students are supervised by over 60 tutors at 23 institutes, and are encouraged to create their own robotics applications. We describe how the laboratory motivates the students to act and think like engineers and to solve real-world issues with limited resources. The evaluation results show that the proposed practical course concept successfully boosts students’ motivation, advances their programming skills, and encourages the peer learning process.

A new otological diagnostic system providing a virtual tube model

Sonotubometry allows for the detection of the dynamic Eustachian tube function under physiological conditions, whether the eardrum is intact or perforated. Quality and reliability of state-of-the-art sonotubometry have been substantially improved by a new real-time system for otological diagnostics. Moreover, this diagnostic system provides a time-variant virtual model of the Eustachian tube as a new feature, which opens up entirely new possibilities in monitoring Eustachian tube openings. In this work we investigate the correlation of the virtual model to the human anatomy.

R437 – Sonotubometry With Perfect Sequences in Pathologic Ears

Problem Sonotubometry is a non-invasive method for the evaluation of Eustachian Tube (ET) function. Perfect Sequences (PSQE) allow monitoring the ET under physiologic conditions in healthy ears. This study investigates the use of this new approach in pathologic ears. Methods Forty individuals were examined. Group A: n=20 individuals (40 normal ears). Group B: n= 11 patients (16 ears) with acute/subacute ET dysfunction. Group C: n=9 patients with chronic problems requiring tympanoplasty. Sonotubometry was performed before and after operation. As opening maneuvers, yawning, dry swallowing, water swallowing, and Toynbee were employed. Results In group A an ET opening was seen in 77.06% maneuvers and in all patients. The median amplitude (A) of sound increase was 16.64 dB, the duration of the openings (D) was 365 ms. In group B these values were 34.39%, A = 9.27 dB, D=311 ms before and 72.26%, A= 19.51 dB and D=329 ms after operation (myringotomy/tympanostomy). Group C showed openings in 33.83% with A=9.78dB and D=365 ms. There was no significant change after surgery. Conclusion The comparison between normal ears and acute ET dysfunction shows sonotubometrical a return of the normal function after operation within a week in most ears. The results demonstrate that the findings occur not only due to an improved sound transmission through the dry middle ear but from a recovering ET. The results in Group C show that the ET dysfunction is chronic. Significance Sonotubometry with PSQE is feasible for assessment of ET (dys)function under physiological conditions. It has therefore the potential to open new perspectives on ET monitoring. Support Supported by DFG-grant MA 3917/1-1.

08:20 AM: Assessment of Eustachian Tube with Perfect Sequences

in rats to examine whether the presence of a cochlear implant alters the risk of pneumococcal meningitis postimplantation. Three different routes of spread of infection (hematogenous, middle ear, and inner ear) from the upper respiratory tract mucosa to the meninges were examined. RESULTS: The presence of a cochlear implant reduced the threshold of bacteria required to cause pneumococcal meningitis from all three routes of infection examined. The presence of severe inner ear trauma to the osseous spiral lamina also reduced the threshold for direct spread of infection from the middle ear to the central nervous system via the inner ear. CONCLUSION: It has been demonstrated that the threshold for pneumococcal meningitis is lowered following cochlear implantation, and that severe trauma to the OSL reduces this threshold further if the infection involves the middle or inner ear. Future research will determine whether surface modification of the cochlear implant electrode array and/or pneumococcal vaccination can reduce the risk of pneumococcal meningitis following cochlear implantation. SIGNIFICANCE: In early detection and treatment of pneumococcal infection such as otitis media, pneumococcal bacteremia may be required in implant recipients as the experimental data suggests the cochlear implantation leads to a reduction of threshold for meningitis. Cochlear implant design and the insertion technique should be least traumatic to the bony structures within the inner ear in order to reduce the risk of pneumococcal meningitis. SUPPORT: The Garnett Passe and Rodney Williams Memorial Foundation Scholarship in Otolaryngology Head and Neck Surgery; The Wagstaff Fellowship, Royal Victorian Eye & Ear Hospital; NIH-NIDCD-N01-DC-3-1005; the Bionic Ear Institute and the Department of Otolaryngology, University of Melbourne.