|Document ID (ISN)||31707|
|Convention or series no.
||Godenhielm B., Perkiö K., Starck J.
||Effect of helmet underhats on the attenuation of earmuffs
||Kypärän alushupun vaikutus kuulonsuojainten toimintaan [in Finnish]|
||Työterveyslaitoksen tutkimuksia 148, Institute of Occupational Health (Työterveyslaitos), Helsinki, Finland, 1979. 39p. Illus. 14 ref. Price: Fmk.20.00.
||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.
||chain saws; sound attenuation; logging; earmuffs; safety helmets; weather protective clothing
||winter; comparative study; noise
||E - Books, reports, proceedings
||Noise, hearing and vibration
|Broad subject area(s)
Forestry and logging
Hand and portable tools