Design and implementation of an odiometer

The aim o-F this study is the design and implementation of an odiometer. The instrument under consideration is capable of generating test signals with eleven standart -Frequencies such as 125,250,500,750,1000,1500,2000,3000,4000,6000 and 8000 Hz. On the other hand, intensity o-F each test signal can be chosen at twelve different levels such as 0, 10,20,..., 1 10 dB. The selection o-F -Frequencies and intensity levels are made by means o-F two pairs o-f up and down counting buttons independently. Digital reading -Facilities for the above cited selections are also available. All the necessary commutations have been realized by using digitally cotrolled analog switches so as to prevent undesired contact problems. On the other hand, main blocks have been designed as voltage controlled to minimize the noise that can probably appear especially at the inputs of the power amplifiers. A masking unit generating narrow-band white IVnoise is also included in the instrument. The masking noise is generated by filtering a digital random generator, The -Filter stage consists of two cascaded voltage- controlled active band-pass -Filter sections. 8ince there is no commercial intention in this project a masking intensity level adjustment unit operating under the control of the test signal amplifier unit has been considered sufficient. It can finally be stated that there is no problem going into mass production of this instrument and the instrument whose design and implementation has been achieved can be used as a prototype, at worst case, with very few modifications. Science codes 404.01.01 Key words: Odiometer, Pure tone, Noise, Masking, Narrow band white noise, Digital controlled analog switch.