Even moderate 70 dB sound causes temporary hearing threshold shift with hours of exposure

Evidence

As discussed earlier, a high enough noise exposure can cause the sensitivity of hearing to decrease, and consequently the hearing thresholds to increase. If the exposure is under certain limits, the hearing thresholds can recover after the exposure, fully or to some extent. This phenomenon is called the temporary threshold shift (TTS). The level and duration of the TTS are affected by the level and duration of sound. Figure 19.4a shows the increase in hearing threshold as a function of time for different sound levels. Even a sound of 70 dB SPL is capable of generating a minor TTS when the exposure time is several hours. Sound pressure levels of over 100 dB SPL increase the hearing threshold rather quickly. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 2688

Categorization

• XREF: Connects to earlier soundscape work on chronic urban noise levels and their health effects. — connects to: Ringing ears indicate damage even below the 85 dB threshold — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 689