Tympanic Tinnitus Acoustics Signal Detector Using MEMS Microphones Detector de señales acústicas de Tinnitus Timpánicos usando micrófonos MEMS H.V. Robles1, A.V. Molina2, L.J. Martinez2, J.A. Aldonate3, and R. Vergara4 1
Facultad de Ciencias e Ingenierías, Unisinú - DEMA. Montería, Colombia Facultad de Ingeniería, Ingeniería Biomédica ECCI y GINIC-HUS. Bogotá, Colombia 3 Facultad de Ingeniería UNER y LIRINS, Oro Verde, Entre Ríos, Argentina 4 Hospital Universitario de la Samaritana, HUS, Bogotá, Colombia
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[email protected] 2
Abstract— this paper presents the results obtained in the design and implementation of a tool for the objective detection tympanic Tinnitus in patients with this condition equipment. To date, there are no diagnostic methods to determine the psychoacoustic characteristics of the symptom (tinnitus), making the subjective and of little clinical reliability by having no real physical record diagnosis. Therefore, it presents a design of a machine tool capable of picking up sound signals generated in the hearing of patients with these symptoms. The methodology used for the recording and study of the captured signals was measured by putting a sound signal with an otoscope type MEMS (MicroElectroMechanical Systems) microphone in the ear canal of the subject, transmit and store them on a PC using the SPECTRAplus Software. Besides the database (Epicrisis) of some patients from the University Hospital of the Samaritan (HUS) who presented symptoms of Tinnitus is analyzed, finally the document results and conclusions are presented. Keywords— Tinnitus, MEMS microphones, Biomedical equipment. I. INTRODUCTION
Tinnitus is a condition that affects about 17% of the world population, is defined as the perception of sound, be it a buzzing, ringing, whistle, bell, whistle, or similar [1]. Others claim it is a sound that is generated in the brain and is called Tinnitus typical [2]. Because each of the authors defines the Tinnitus according to their research, then comes the discussion between Objective Tinnitus Subjective Tinnitus and [3]. Subjective Tinnitus is known as the emergence of an internal sound can only be heard by the patient, while the Objective Tinnitus is defined as the presence of a sound or buzz may be heard by the patient and the medical specialist in the most cases, an otolaryngologist (ORL) [4]. Currently, statistically speaking that approximately 10% to 15% of the world population has symptoms of Tinnitus [5, 6]; for example, in the U.S., there is a prevalence of 45 per 1,000, indicating a prevalence rate of 4.5%, at least 12.2 million people in the U.S. suffer from Tinnitus. Table I Tinnitus prevalence in other countries shown. Extrapolating these data to Colombia, where a population of about 42 million
people are estimated to have prevalence rate of 1'900 .000 inhabitants suffering from Tinnitus. Table 1. Tinnitus Statistics by country [7]. People People with Tinnitus Country (Approximately) (Extrapolating) Brazil 184’101.109 8’284.549 Venezuela 25’017.387 1’125.782 Peru 27’544.305 1’239.493 Mexico 104’959.594 4’723.181 Germany 82’424.609 3’709.107 Spain 40’280.780 1’812.635 Colombia 42’310.775 1’903.984 USA 293’655.405 13’214.493 Japan 127.333.002 5'729.985
The severity of the Tinnitus is very high, because the greater the number of patients with tinnitus that the number of patients seeking treatment [8]. You can tell that some of the activators of Tinnitus include: emotional labor and stress, physiological factors, exposure to loud noises, unemployment and mental and physical illness [9-10]. Therefore, the aim of this paper is to describe the results obtained when experimenting with equipment designed to detect and record the signals generated by the Tinnitus condition for the corresponding study also compare the results obtained with the database of patients University Hospital of the Samaritan. Mentioned in the medical literature from 3000 BC in Egyptian papyri, also Hippocrates, Galen and Celsius in his writings to defer Tinnitus; however progress in clarifying their nature and have been very few therapeutic [11]. Although testing kits are developed Tinnitus in different countries, based on other subjective principles that depend on the patient's response, there is no general consensus. For example, you can find equipment like Acufenometer Objective developed by researcher Ramiro Vergara, Colombian otolaryngologist specializing in the study of tinnitus (Tinnitus) [12], designed to diagnose the Vibratory Tinnitus (Objective Tinnitus) 1995. However, the efficiency only reached 45%, i.e., that 55% of patients not they could diagnose car clearly, and also presented mixed with other signals, preventing
© Springer International Publishing Switzerland 2015 A. Braidot and A. Hadad (eds.), VI Latin American Congress on Biomedical Engineering CLAIB 2014, Paraná, Argentina 29, 30 & 31 October 2014, IFMBE Proceedings 49, DOI: 10.1007/978-3-319-13117-7_35
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Fig. 3 CAE simulator for testing microphones.
After simulating one ear acoustic signal generator low intensity, ie, -86 dB FS, studies were applied using a scanner headphones brand Frye Electronics, model Fonix FP35, where real-ear measurements were used, as the real-ear SPL and IEC60118-7 standard used for normalization of the ear simulators, with reference impedance adapter HA-2 (2cc), electroacoustic IEC60318-5 standard [15]. In these tests sought to look at the real gain of equipment instrument designed as well as its frequency response. Figure 4 shows the connection made for the experiment shown.
Fig. 4 Location of the instrument in the analyzer computer headphone.
Finally, it proceeded to perform measurements in patients with Tinnitus, which were previously evaluated by Dr. Ramiro Vergara. These tests were conducted in the soundproof chamber flag of Otorhinolaryngology, University Hospital of the Samaritan. To study each patient prior authorization Hospital, two formats, one for patient consent and a questionnaire that serves as Tinnitus history for the previous study of possible new causes or similarities in the causes of Tinnitus are designed in the patients studied. IV.
RESULTS AND EXTENTS
The results of the hearing aid analyzer are illustrated in Figure 5, the graph of the frequency response of the target Acufenómetro thrown by analyzer headphones after testing called frequency shift is shown.
Fig. 5 Frequency response of the target obtained Acufenómetro with Fonix FP35 hearing aid analyzer.
As can be seen, the gain made for frequencies between 500 Hz and 7 kHz is in a range of 10 dB and 40 dB. The two vertical lines are due to errors in the display of the test in the laboratory to characterize the frequency response of the equipment proposed instrument. Because 79% of Tinnitus in the literature can be described as a pure tone and its range does not exceed 8 kHz according to [16], we chose to implement different tones ranging from 500 Hz this test to After 8,000 Hz in laboratory tests with simulated signals proceeded to perform measurements in patients with Tinnitus, which were previously evaluated by Dr. Ramiro Vergara, ORL specialist. To obtain the database is done in first step; a filtering of patients with the disease (Tinnitus), here obtained a database of about 420 people, which presented in its history the name Tinnitus. 20 patients as a population sample for analysis were chosen instrument. As a result they found that 60% were pregnant women, of which 83.3% had hypertension and 75% had headache. In addition, we found that 25% were men. Of these, two patients were smokers and consumers of alcohol, others had Tinnitus accident; one of them being close to an explosion of dynamite. After testing in patients were made an example of the captured signals is patient 10, male, 53, a native of Bogota, where he serves as a Civil Engineer, who complained a pitched ringing in his two ears, but recounted feel more strongly (intensity) in the left ear, the place you heard the Acufenómetro target for a short period of time similar to that reported by the patient, but with a different gain to the patient described by sound perception. The spectrum of the audio signal obtained from patient 10 shown in Figure 6 the fundamental frequency of the signal is between 3.9 KHz and 4.1 KHz, corroborating expressed by the patient 10 when referring to their tinnitus. According to [15], patient 10 showed a tinnitus around 4 kHz, in the experiment the new instrument using MEMS microphone, shows better capture of the signal.
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intervention studies and procedures for the collection of information, tools and methods used to control data quality.
REFERENCES 1. 2. Fig. 6 Frequency spectrum of the signal of patient 5 Tinnitus. 3. V. CONCLUSIONS
4.
This article presented the first results of the project Tinnitus ECCI-HUS. Equipment proposed instrument shows a sensitivity that allows the perception of acoustic signals up to - 56 dB SPL pure tones ranging from 40 Hz to 8 kHz, showing a very high potential for capturing signals from tympanic vibrations. Equipment proposed instrument is battery-powered, which prevents the line noise, but it was observed that it is necessary to increase hardware filtration step prior to amplification in order to improve the SNR of the prototype. Although Tinnitus symptoms can be caused by various diseases, the signals received in patients 9 and 16 show spectral components at different frequencies, and thus could not confirm that these signals were exactly what they were hearing patients, mainly because of the subjectivity of the definition thereof and description to perceive sound. Patients 10 and 14, corroborated the captured signal is very similar to their tinnitus, but this is not conclusive as to being able to define Tinnitus Tympanic, missing, more extensive and more detailed studies with a concrete plan of analysis, where criteria are used inclusion and exclusion of patients supported by otolaryngologists from an accredited Hospital, and implement procedures for data collection, measuring instruments and methods for quality control of the data. Moreover, the evidence did not show characteristics of repeatability and reproducibility, and which were not carried out in different locations and with other microphones like references. Because of the potential evidence the equipment, it is advisable to continue the study and improvement of the technological tool designed, implemented a guiding protocol in the pavilion specialty ORL in a hospital, where in more depth detail the methodology, is accessible and eligible population, selection and sample size, the inclusion and exclusion criteria, the relevant variables for the study, using strategies to eliminate threats to the validity of results describing the measurements and instrument use,
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