Temporary Hearing Loss Induced by Noise and Vibration

Five male students (19 20 years old) with normal ears were given exposures to (1) steady‐state noise, (2) vibration, and (3) noise and vibration at the same time. In a control experiment the subject sat beside the moving vibrator with ear plugs and earmuffs. Temporary threshold shift (TTS) occurred after both 20 and 60 min of exposure to the vibration of acceleration 500 cm/sec2 and frequency 5 Hz, which is regarded as a resonance frequency of human body. The TTS by a steady‐state noise [101‐dB sound‐pressure level (SPL) broad band] was increased by simultaneous vibration (500 cm/sec2 and 5 Hz).