In Würzburg wird seit 1997 ein Hörscreening unter Verwendung akustisch evozierter Potentiale durchgeführt. Der zu Anfang verwendete Click-Reiz wurde im März 2006 durch den auf dem Cochlea-Modell beruhenden Chirp-Reiz ersetzt. Für diesen Reiz werden auf Grund der Kompensation der Wanderwellenverzögerung der Cochlea größere Potentialamplituden beschrieben. Für diese Arbeit wurden die akustisch evozierten Potentiale von 96 Neugeborenen mit dem Maico-MB11-BERAphon aufgezeichnet. Ausgewertet und verglichen wurden die bei 40 dB HL und 60 dB HL mittels Click und Chirp generierten Potentiale I, III und V hinsichtlich ihrer Auswertbarkeit sowie ihrer Latenzzeiten und Amplitudenwerte. Besonderes Interesse galt den Latenzzeiten des Chirp und dabei der Fragestellung, in wie weit sich die Reizstruktur des Chirps in einer Verkürzung der Latenzzeiten auswirken würde. Die Ergebnisse zeigen, dass der Chirp im Vergleich zum Click zu einer deutlichen Verkürzung der Latenzen der akustisch evozierten Potentiale führt. Bei allen untersuchten Potentialen ergaben sich beim Chirp kürzere mittlere Latenzen als beim Click. Die Unterschiede erwiesen sich als statistisch signifikant. Der Chirp bewirkt eine Vergrößerung der Antwort-Amplituden. Die Mittelwerte aller Amplituden waren bei Verwendung des Chirp-Reizes größer. Eine Verbesserung der Auswertbarkeit wurde für alle untersuchten Potentiale I, III und V nachgewiesen. Zusammenfassend lässt sich feststellen, dass nach Chirp-Reizung die einzelnen Wellen der akustisch evozierten Potentiale also deutlicher, mit größerer Amplitude und mit kürzerer Latenz zur Darstellung kommen als nach Click-Reizung. Die in dieser Untersuchung im Standard-BERA-Verfahren ermittelten Unterschiede zwischen den Reizen Click und Chirp unterstreichen die Vorteile des Chirp auch für den Einsatz beim Hörscreening und der Hörschwellenbestimmung. Die durch diesen Reiz evozierte Potentialantwort führt bei kürzeren Messzeiten zu deutlich zuverlässigeren Ergebnissen, was eine Verbesserung der Qualität der Hörschwellenbestimmung und der Hörscreening-Untersuchung darstellt. / Since 1997 there is a Hearingscreening established in Wuerzburg which is based on auditory evoked potenials. In March 2006 the formerly used click-stimulus was substituted by a chirp-stimulus based on the cochlea-model. For this stimulus larger amplitudes of the potentials are discribed due to a compensation of travelling wave delay. For this study the auditory evoked potentials of 96 newborns were recorded with the Maico-MB11-BERAphon. Potentials I, III and V were evaluated and compared in terms of evaluability as well as latency and amplitude values. The latencies of the chirp-stimulus and the question, to which extent the structure of the chirp-stimulus would result in a reduction of latency times were of main interest. The results show that compared to the click the chirp-stimulus causes a clear shortening of latencies of auditory evoked potentials. For all examined potentials the chirp-stimulus showed shorter mean-latencies than the click. The differences were statistically significant. The chirp causes an increase in response amplitudes. Mean values of amplitudes were larger when using the chirp stimulus. An improvement of the evaluability was demonstrated for all investigated potentials I, III and V. In summary it can be seen that after Chirp excitation the individual waves of auditory evoked potentials occur more clearly, with greater amplitude and shorter latency than after click excitation. The differences between the click and chirp stimuli identified in these standard ABR procedures also emphasize the benefits of the chirp-stimulus for use in hearing screening and the defining of hearing thresholds. The potential response evoked by this stimulus leads to more reliable results implying significantly shorter measuring times and thus improves the quality of the defining of hearing thresholds and hearing screening examination.

The first part of the thesis focuses on theory and deals with the basic physical terms as far as acoustics is concerned. It also deals with a description of auditory system, as well as graphical results of audiometrical methods. The second part to the thesis deals with a scheme of audiometer for hearing tests. It also deals with the description of the programme as well as the transfer of the decibel scale to electric voltage and its correction. The last chapter contains the data collected during the hearing tests.

Human hearing is to collect information from the outside world and is one of the basic human senses. Part of this thesis is devoted to acoustics, properties of the human ear in terms of perception of sounds and methods, which human ears are investigating. Audiometer is an instrument which is most often used in healthcare. The main content of this thesis is to design pure tone audiometer, which is important for the subjective tests of human hearing non-invasive method.

Exostoses are surface periosteophyte inside the external auditory canal of the human ear. The main objective of the diploma thesis is to determine the potencial impact of the narrowing of external auditory canal by exostoses on the mechanical sound transmission into the internal ear. The task was solved by FEM modelling in the ANSYS system. The simple finite element 2D model of the normal human ear was used and it has been taken from the diploma thesis B Ouali: Development of 2D finite element model of human ear (BUT Brno, 2009). At the model, including the external ear canal, elastic eardrum, otitis cavity with otitis ossicles and the cavity of the internal ear with internal ear partition, the alterations simulating different size of narrowing a and different positionig of exostoses were done. The influence of the exostoses on the sound transfer characteristics for air sound transmission and for bone sound transmission was discused. The results were analysed and compared with audiology.

Evoked potentials are electric brain response to external stimulus. They are important diagnostic no visual method in neurology. For their excitation use of different of kinds stimulation, most often: visual, auditory, somatosenzory, olfactory and gustatory. Evoked potentials are objective method for measurement sense perception. This master’s thesis is specialized to auditory evoked potentials and design acoustic generator for their stimulation. Auditory evoked potentials are primary used for objective audiometry, but they have another usage. In the first place, application is specialized on health sector. The aim of this master’s thesis is compact specified medical requirements with available technical resources.

The presented master’s thesis deals with the acoustics, specifically with the selected characteristics of the sound. It focuses on the anatomy of the auditory system and its function. The work describes the testing approaches for an evaluation of the auditory organ function and introduces modern methods used for the hearing tests, especially pure tone audiometry. A part of the thesis is dedicated to a concept of an audiometer for pure tone audiometry, which is presented in a detailed block diagram along with a description of its working components. Included chapters describe the partial circuits of the audiometer supplemented by the calcuations of its individual elements. The concluding part of the thesis deals with the evaluation of the device’s functionality.