EFFECTS OF INTENSIVE NOISE AND OTHER ENVIRONMENTAL FACTORS ON HUMAN AUDITORY FUNCTIONS

Measurements of the auditory functions were made successively on normal human subjects staying in a stressing experimental environment. One of the main straining factors was the noise recorded from an engine and reproduced by loudspeakers. The daily dosage of exposure was:110dB for 1 hr., 104 dB for 3 hrs., 95 dB for 4 hrs. and 75 dB for 16 hrs. Other environmental conditions consisted of high room temperature (35℃, 8 hrs. daily), high relative humidity, narrow space of residence, limitation of water supply, moderate mental and physical loading etc. Pure tone thresholds, differential threshold of pitch and of loudness, accuracy of sound localization and immediate memory of speech signals were chosen as indices to assess the auditory functions.