M. Bak, K. Rosniak-Bak
Journal of Biomedical Engineering and Technology. 2013, 1(3), 31-35DOI:
Abstract: The aim of this study was to develop a prototype generator with electro-acoustical connection, verify the parameters of the new apparatus, perform clinical trials in patients with normal hearing. A digital oscilloscope and artificial ear were used to check electrical and sound parameters. Sound intensity in the 0.5-20 kHz frequency range was 86.8 ± 9 dB SPL. This was followed by clinical trials involving 44 volunteers (17 men and 27 women) with an average age of 20. Before the experiment, each volunteer was examined by audiological tests to rule out damage to the auditory pathway. The upper frequency limit of hearing procedure consisted of binaural administration of constant-intensity signal with a frequency smoothly varying within the 20 kHz - 0.5 kHz range. The volunteer was told to release a signaling button when he heard the acoustic signal. At that moment, the generator stopped at a given frequency that was displayed on a digital scale unit. The test procedure was repeated three times in each subject and the arithmetic mean of three measurements was used in further analysis. The entire procedure, both technical and clinical, was conducted in an audiometric silent chamber, in which it was possible to control the acoustic conditions. Comparison of results of a prototype apparatus to the results obtained in previously research showed that the developed apparatus specifications meet their objectives. In clinical studies, the upper frequency limit of hearing results were as follows: in the group of 17 people only one person was below 75 percentile, two were at 75 percentile, ten at 50 percentile, and four were at 25 percentile. The results show that the modification of the apparatus involving the use of less expensive components has allowed to obtain the technical parameters and results comparable to the others authors and, therefore, the apparatus built by the author of this paper may be used as a screening apparatus.