ANSI ASA S12 pdf free download
ANSI ASA S12 pdf free download.Methods for Measuring the Real-Ear Attenuation of Hearing Protectors.
3 Terms and definitions
For the purposes of this standard, the terms and definitions given in ANSI/ASA Si .1, ANSI/ASA S3.20, and the following apply:
3.1 active hearing protection device. A hearing protection device that contains electronic components including transducers (i.e., speakers and microphones) to affect the transmission of sound into the earcanal.
3.2 amplitude-sensitive hearing protection device. A hearing protector, also referred to as a level- dependent hearing protector, which is designed to exhibit a change in attenuation as a function of sound level.
3.3 earmuff. A hearing protector usually comprised of a headband and earcups with a soft cushion to seal against the head, intended to fit against the pinna (supra-aural) or the sides of the head around the pinna (circumaural). The earcups may also be held in position by attachment arms mounted on a hard hat or hard cap.
3.4 earplug. A hearing protector that is inserted into the earcanal.
3.5 hearing protection device (HPD). A personal device, also referred to as a hearing protector, worn as a barrier to reduce the sound level entering the earcanal in order to diminish the harmful auditory and/or annoying subjective effects of sound.
3.6 helmet. A device, sometimes functioning as a hearing protector, which usually covers a substantial portion of the head, that may include internally mounted earcups and/or earplugs.
3.7 occluded threshold of hearing. At a specific frequency, the minimum effective sound pressure level of the signal that is capable of evoking an auditory sensation in a specified fraction of the trials when the hearing protector under test is worn.
3.8 open threshold of hearing. At a specific frequency, the minimum effective sound pressure level of the signal that is capable of evoking an auditory sensation in a specified fraction of the trials when a hearing protector is not worn (i.e., ears unoccluded).
3.9 passive hearing protection device. A hearing protector that relies solely on its mechanical elements to block or otherwise control the transmission of sound to the auditory system.
3.10 pink noise. Noise for which the spectrum density varies as the inverse of frequency.
3.11 random incidence. Incidence of sound waves from all directions with equal probability.
3.12 real-ear attenuation at threshold (REAT). At a specific frequency, the mean value (in decibels) of the occluded threshold of hearing minus the open threshold of hearing on all trials under otherwise identical test conditions, either for a single listener or averaged across a group of listeners.
3.13 reference point. A fixed spatial location within the test chamber to which all of the objective measurements of the sound field characteristics are referenced and which coincides with the midpoint of a line connecting the test subjects’ earcanal openings when the subject is seated for measurements.
3.14 requester. The party submitting a hearing protection product and fitting instructions for testing.
NOTE When the investigator is evaluating hearing protectors other than for an entity external to the laboratory, the requester is considered to be the investigator conducting the research.ANSI ASA S12 pdf download.
