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An example of absolute threshold of hearing would be hearing a watch ticking twenty feet (six metres) away from a subject in a quiet room. [14] The threshold of hearing is generally reported as the RMS sound pressure of 20 μPa (micropascals) = 2×10 −5 pascal (Pa).
The absolute threshold of hearing (ATH), also known as the absolute hearing threshold or auditory threshold, is the minimum sound level of a pure tone that an average human ear with normal hearing can hear with no other sound present. The absolute threshold relates to the sound that can just be heard by the organism.
In measuring sensory threshold, noise must be accounted for. Signal noise is defined as the presence of extra, unwanted energy in the observational system which obscures the information of interest. As the measurements come closer to the absolute threshold, the variability of the noise increases, causing the threshold to be obscured. [5]
An absolute threshold is the level of intensity at which a subject can detect the presence of a stimulus a certain proportion of the time; a p level of 50% is commonly used. [16] For example, consider the absolute threshold for tactile sensation on the back of one's hand.
A tone at the frequency of 4000 Hz is presented for 60 seconds at an intensity of 5 decibels above the patient's absolute threshold of hearing. If the patient stops hearing the tone before 60 seconds, the intensity level is increased by another 5 decibels with the procedure repeated until the tone can be heard for the full 60 seconds or until no decibel level can be found where the tone can be ...
A basic measure of hearing is afforded by an audiogram, a graph of the absolute threshold of hearing (minimum discernible sound level) at various frequencies throughout an organism's nominal hearing range. [6] Behavioural hearing tests or physiological tests can be used to find the hearing thresholds of humans and other animals.
This prevents the non-test ear from detecting the test signal presented to the test ear. The threshold of the test ear is measured at the same time as presenting the masking noise to the non-test ear. Thus, thresholds obtained when masking has been applied, provide an accurate representation of the true hearing threshold level of the test ear. [13]
In 1962, Eugene Galanter, a psychologist, tested stimuli till people were able to feel them approximately 50% of the time, then used the following as examples of absolute threshold: [9] Visual – On a clear, dark night a candle can be seen from approximately 30 miles away.