IEC 61669 pdf download.Electroacoustics – Equipment for the measurement of real-ear acoustical characteristics of hearing aids
This International Standard specifies the general requirements for test equipment designed for use in measuring the real-ear acoustical characteristics of hearing aids and describes the terminology used. The purpose of this International Standard is to ensure that measurements of real-ear acoustical characteristics of a hearing aid on a given human ear, performed with different test equipment which comply with this International Standard using methods described in ISO 1 21 24, shall give substantially the same results.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this part of the ISO/IEC Directives are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. IEC 60601 -1 , Medical electrical equipment – Part 1 : General requirements for safety IEC 60601 -1 -2, Medical electrical equipment – Part 1 : General requirements for safety – 2. Collateral standard: Electromagnetic compatibility – Requirements and tests IEC 60601 -1 -4, Medical electrical equipment – Part 1 : General requirements for safety – 4. Collateral standard: Programmable electrical medical systems IEC 60645-1 , Audiometers – Part 1 : Pure tone audiometers IEC 60942, Electroacoustics – Sound calibrators ISO 266, Acoustics – Preferred frequencies
3 Terms and definitions
For the purpose of this International Standard, the following terms and definitions apply: 3.1 test signal acoustic signal at the field reference point 3.2 subject person in whose ear the hearing aid performance is characterized 3.3 subject reference point point bisecting the line joining the centres of the openings of the ear canals of the subject (at the junction between concha and ear canal) NOTE In cases of severe head shape abnormality or asymmetry, it may not be easy to determine the reference point of the subject. The subject reference point used should then be stated. 3.4 test axis line joining the subject reference point to the sound source passing along the axis of the sound source 3.5 working distance distance from the subject reference point to the plane of the mounting ring or protective grille of the sound source measured along the test axis 3.6 sound pressure level (SPL) twenty times the logarithm to the base 1 0 of the ratio of a given root-mean-square sound pressure to the reference sound pressure (IEV 801 -22-07, modified) NOTE Throughout this International Standard all sound pressure levels refer to 20 µPa. 3.7 band sound pressure level sound pressure level measurement for a defined band 3.8 test signal level level of the test signal expressed as a sound pressure level in decibels (dB) NOTE For broad-band signals, the frequency spectrum should be specified and stated. 3.9 equalization process of controlling the test signal level as a function of frequency such that it does not vary from the desired level 3.1 0 reference microphone controlling microphone microphone used to measure the test signal level in the measurement process and/or to control it in the equalization process 3.1 1 sound inlet aperture through which sound enters a microphone and at which the microphone is calibrated NOTE In the case of a probe microphone (see 3.1 3) which includes an extension tube, this will be the open end of the probe tube.3.1 2 field reference point point at which the sound inlet of the reference microphone is located during equalization and/or measurement 3.1 3 probe microphone microphone adapted to determine the sound pressure level in the ear canal NOTE The probe microphone may include an extension tube. 3.1 4 test ear ear of the subject in which the sound inlet of the probe microphone is placed 3.1 5 measurement point point in the ear canal of the test ear at which the sound inlet of the probe microphone is placed 3.1 6 test signal type identification of the test signal in terms of its frequency spectrum and/or temporal properties 3.1 7 concurrent equalization real time equalization equalization performed at the time of measurement based on the monitoring of the test signal level