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Document ID (ISN)31707
CIS number 79-1290
ISBN(s) 951-801-118-4
Year 1979
Convention or series no.
Author(s) Godenhielm B., Perkiö K., Starck J.
Title Effect of helmet underhats on the attenuation of earmuffs
Original title Kypärän alushupun vaikutus kuulonsuojainten toimintaan [in Finnish]
Bibliographic information Työterveyslaitoksen tutkimuksia 148, Institute of Occupational Health (Työterveyslaitos), Helsinki, Finland, 1979. 39p. Illus. 14 ref. Price: Fmk.20.00.
Abstract 3 types of earmuffs and cloth and fur underhats were studied by using 13-15 chain saw operators. The difference in attenuation with and without the underhat was measured as the change in the hearing threshold of the subject with Békésy audiometry. An artificial ear (IEC 318 standard) was used for measuring the 1/3 octave band noise at -10° to -20°C. The attenuation of the earmuffs was determined at 20° and -15°C by a miniature microphone attached to the ear tip. The cloth underhat decreased the attenuation by 5dB and the fur hat decreased it to almost zero at frequencies below 1.5kHz. At higher frequencies there was some attenuation with the fur hat and it increased about 15dB/octave. When the earmuffs were against the skin under the hat, the attenuation increased about 24dB compared to the attenuation with earmuffs and without the hat. In the cold environment the attenuation increased at low frequencies and decreased at high frequencies. English summary.
Descriptors (primary) chain saws; sound attenuation; logging; earmuffs; safety helmets; weather protective clothing
Descriptors (secondary) winter; comparative study; noise
Document type E - Books, reports, proceedings
Subject(s) Noise, hearing and vibration
Broad subject area(s)
Browse category(ies) Head protection
Hearing protection
Forestry and logging
Hand and portable tools
Protective clothing