threshold shift threshold shiftan increase (worsening) in the threshold of hearing for an ear at a specified frequency Related Articles: Hot Topic – Guidance on Determining Potential Effects to Marine Mammal HearingCriteria for Effects of Anthropogenic Sound on FishesReference List: Animals and SoundHearing Loss in MammalsHearing Loss in FishesPile drivingHow is sound used to protect marine mammals?Tutorial: Mammals – Hearing lossMarine Mammal Hearing AttenuationOcean Sound Policies Chris Knowlton2017-02-26T20:10:02-05:00