Intercomparison of measurements on ear protectors by subjective and objective methods
The document is the collection of the individual reports of the laboratories which participated in the intercomparison campaign. A synthesis report is published full size with the same title (EUR 10575 EN). Samples of four different types of earmuffs and one type of ear plugs were used to compare attenuation results obtained by five national test laboratories testing to ISO 4869 (subjective method). One laboratory also measured in accordance with the AFNOR standard NF S31-062-1982. The objective measurements on the earmuffs were carried out following ISO/DIS 6290 (Draft). Repeated subjective testing of attenuation within one laboratory showed an average spread of 2dB. The differences between some laboratories increased to 5dB. The results for the insertion loss (objective method) varied between laboratories by 6dB. Resonances at low frequencies (100 - 250 Hz) were detected. The agreement of attenuation measurements on ear plugs do not agree better than +/- 6dB. The ISO test method generally gave attenuation values higher by 2dB than the AFNOR method. Recommendations for improvements of the ISO standards are given.
Bibliographic Reference: EUR 12974 EN (1990) 310 pp., MF, ECU 10
Record Number: 199011080 / Last updated on: 1994-12-01
Original language: en
Available languages: en