La presente tesis propone el desarrollo de un sistema prototipo de estetoscopio digital para ser usado en consultas médicas remotas, utilizando transmisión por la red celular (GSM) e Internet, con la finalidad de brindarle a los profesionales en la salud una herramienta con la cual puedan seguir realizando sus consultas cotidianas evitando el contacto directo con el paciente, por ende, previniendo el contagio de una enfermedad infecciosa. Por ello, el presente trabajo se divide en tres partes: la adquisición y transmisión de las señales de auscultación, el servidor Web y el software de control. El primer paso que se debe realizar es la adquisición de la señal acústica proporcionada por el estetoscopio. Las señales ingresan al controlador para su grabación y ser transmitidas vía Internet al servidor Web. Además, previo a la grabación de las señales, el médico, utilizando el software de control, podrá escuchar la señal acústica en tiempo real mediante una llamada a celular para indicar al paciente la correcta posición del estetoscopio. En el servidor se encuentran las grabaciones ordenadas en carpetas con los datos del paciente, dichos archivos son descargables y reproducibles. El método de validación se realizó con una encuesta y pruebas del prototipo con diferentes médicos. Los resultados obtenidos demostraron que el prototipo brinda una buena calidad de los sonidos auscultados, siendo así útil para poder realizar un diagnóstico preliminar certero de manera remota. / The present thesis proposes the development of a digital stethoscope prototype system to be used in remote medical attentions using the celular network transmittion (GSM) and Internet, in order to provide to health professionals a tool which they can keep making their attentions avoiding physical contact with the patient. Thus, preventing the spread of an infectious disease. Therefore, the present work is divided in three parts: the acquisition and transmisión of auscultation signals, the Web server and the software. The first step to take is the acoustic signal acquisition provided by stethoscope. Signals enter the controller for recording and transmitted via Internet to Web server. Also, prior to recording the signals, the doctor, using the software, can hear the eliminate signals in real time using the call in order to indicate the correct position of stethoscope to patient. The recordings are stored on the Web server arranged in folders with data patient, the files are downloadable and playable. The validation method was performed using an inquest and testing prototype with different doctors. The results obtained showed that prototype provides a good quality of auscultated sounds, thus being useful to be able to carry out an accurate preliminary diagnosis remotely. / Tesis

For this project, the design, implementation, characterization, calibration and possible applications of a multiple transducer stethoscope apparatus were investigated. The multi-transducer sensor array design consists of five standard stethoscope diaphragms mounted to a rigid frame for a-priori knowledge of their relative spatial locations in the x-y plane, with compliant z-direction positioning to ensure good contact and pressure against the subject’s skin for reliable acoustic coupling. When this apparatus is properly placed on the body, it can digitally capture the same important body sounds investigated with standard acoustic stethoscopes; especially heart sounds. Acoustic signal inputs from each diaphragm are converted to electrical signals through microphone pickups installed in the stethoscope connective tubing; and are subsequently sampled and digitized for analysis. With this system, we are able to simultaneously interrogate internal body sounds at a sampling rate of 2 KHz, as most heart sounds of interest occur below 200 Hz. This system was characterized and calibrated by chirp and impulse signal tests. After calibrating the system, a variety of methods for combining the individual sensor channel data to improve the detectability of different signals of interest were explored using variable-delay beam forming. S1 and S2 heart sound recognition with optimized beam forming delays and inter-symbol noise elimination were investigated for improved discernment of the S1 or S2 heart sounds by a user. Also, stereophonic presentation of heart sounds was also produced to allow future investigation of its potential clinical diagnostic efficacy.