Dear colleagues, As part of the background work for an update to the Danish guidelines for mitigating impact from pile driving noise we have undertaken a review of the numerous experiments on Temporary Threshold Shift in harbour porpoises and phocid seals conducted in recent years – studies that are too new to be included in the most recent guidance from NOAA/Southall et al. We are pleased to share the paper (open access) through JASA’s website: Jakob Tougaard, Kristian Beedholm, and Peter T. Madsen "Thresholds for noise induced hearing loss in harbor porpoises and phocid seals", The Journal of the Acoustical Society of America 151, 4252-4263 (2022) https://doi.org/10.1121/10.0011560 Abstract: Intense sound sources, such as pile driving, airguns, and military sonars, have the potential to inflict hearing loss in marine mammals and are, therefore, regulated in many countries. The most recent criteria for noise induced hearing loss are based on empirical data collected until 2015 and recommend frequency-weighted and species group-specific thresholds to predict the onset of temporary threshold shift (TTS). Here, evidence made available after 2015 in light of the current criteria for two functional hearing groups is reviewed. For impulsive sounds (from pile driving and air guns), there is strong support for the current threshold for very high frequency cetaceans, including harbor porpoises (Phocoena phocoena). Less strong support also exists for the threshold for phocid seals in water, including harbor seals (Phoca vitulina). For non-impulsive sounds, there is good correspondence between exposure functions and empirical thresholds below 10 kHz for porpoises (applicable to assessment and regulation of military sonars) and between 3 and 16 kHz for seals. Above 10 kHz for porpoises and outside of the range 3–16 kHz for seals, there are substantial differences (up to 35 dB) between the predicted thresholds for TTS and empirical results. These discrepancies call for further studies. Best regards Jakob ************************************************************************* Jakob Tougaard, Ph.D. Professor in Marine Conservation Ecology Department of Bioscience, section for Marine Mammal Research Aarhus University Building 1131 C.F. møller’s Allé 3 DK-8000 Aarhus Denmark Phone: +45 4098 4585 E-mail: jat@bios.au.dk<mailto:jat@bios.au.dk> CVR/VAT: 31119103 EAN: 5798000419988