Preliminary Report:Studies on the Temporary Hearing Threshold Shift at Different Frequencies After Exposure to Various Octave Bands of Noise

In 220 persons studies were made of the temporary threshold shifts (TTS) of hearing 15 minutes after cessation of exposure for 2 hours to various types of octave-band filtered white noise with sound pressure levels ranging from 75 to 115 dB. As regards the bands 75–150, 150–300, 600–1200 and 2400–4800 cps, the power to produce TTS was least at 75–150 cps and increased with each octave band up to 2400–4800 cps. At the latter band the effect was approximately similar to that at 4800–10, 000 cps. For the lower part of the frequency spectrum the results were largely in conformity with the “damage risk criterion” according to Hardy, but there was discrepancy at higher frequencies.