all persons 74.6% (73.2%, 75.9%) N = 15,106. The acoustic reflex mostly protects against low frequency sounds. When triggered by sounds 20 dB above the reflex threshold, the stapedius reflex decreases the intensity of the sound transmitted to the cochlea by around 15 dB. The acoustic reflex is also invoked when a person vocalizes. In humans, the vocalization-induced stapedius reflex reduces sound intensities reaching the inner ear by approximately 20 decibels. The reflex is triggered in anticipation of the onset of vocalization. While the vocalization-induced stapedius reflex in humans results in an approximate 20 dB reduction in transduction to the inner ear, birds have a stronger stapedius reflex that is invoked just before the bird tweets. Hypothesized function The main hypothesized function of the acoustic reflex is the protection of the organ of Corti against excessive stimulation (especially that of the lower frequencies). This protection has been demonstrated both in humans and animals, but with limited effects. According to the article Significance of the stapedius reflex for the understanding of speech, the latency of contraction is only about 10ms, but maximum tension may not be reached for 100 ms or more. According to the article Le traumatisme acoustique, the latency of contraction is 150 ms with noise stimulus which SPL is at the threshold (ATR), and 25–35 ms at high sound pressure levels. Indeed, the amplitude of the contraction grows with the sound pressure level stimulus. Because of this latency, the acoustic reflex cannot protect against sudden intense noises. However, when several sudden intense noises are presented at a pace higher than 2–3 seconds of interval, the acoustic reflex is able to play a role against auditory fatigue. Moreover, the full tension of the stapedius muscle cannot be maintained in response to continued stimulation. Indeed, the tension drops to about 50% of its maximum value after a few seconds. In damage risk criteria for exposure to impulse noise, the acoustic reflex is integral to the Auditory Hazard Assessment Algorithm for Humans model and the Integrated Cochlear Energy models. These two models estimate the response of the basilar membrane in response to an input stimulus and summate the vibration of the segments of the basilar membrane to predict the potential risk for hearing loss. The acoustic reflex can be activated before an impulse reaches the ear through an assumed conditioned response or it can be activated after the stimulus exceeds a