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Threshold Of Pain
The threshold of pain or pain threshold is the point along a curve of increasing perception of a stimulus at which pain begins to be felt. It is an entirely subjective phenomenon. A distinction must be maintained between the stimulus (an external thing that can be directly measured, such as with a thermometer) and the person's or animal's resulting pain perception (an internal, subjective thing that can sometimes be measured indirectly, such as with a visual analog scale). Although an IASP document defines "pain threshold" as "the minimum intensity of a stimulus that is perceived as painful", it then goes on to say (contradictorily in letter although not in spirit) that: Traditionally the threshold has often been defined, as we defined it formerly, as the least stimulus intensity at which a subject perceives pain. Properly defined, the threshold is really the experience of the patient, whereas the intensity measured is an external event. It has been common usage for most pain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Day 80 - A Pain In The Neck (2347498204)
A day is the time rotation period, period of a full Earth's rotation, rotation of the Earth with respect to the Sun. On average, this is 24 hours (86,400 seconds). As a day passes at a given location it experiences morning, afternoon, evening, and night. This daily cycle drives circadian rhythms in many organisms, which are vital to many life processes. A collection of sequential days is organized into calendars as Calendar date, dates, almost always into weeks, months and years. A solar calendar organizes dates based on the Sun's annual cycle, giving consistent start dates for the season, four seasons from year to year. A lunar calendar organizes dates based on the Moon's lunar phase. In common usage, a day starts at midnight, written as 00:00 or 12 am, 12:00 am in 24-hour clock, 24- or 12-hour clocks, respectively. Because the time of midnight varies between locations, time zones are set up to facilitate the use of a uniform standard time. Other conventions are sometimes us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loudness
In acoustics, loudness is the subjectivity, subjective perception of sound pressure. More formally, it is defined as the "attribute of auditory sensation in terms of which sounds can be ordered on a scale extending from quiet to loud". The relation of physical attributes of sound to perceived loudness consists of physical, physiological and psychological components. The study of apparent loudness is included in the topic of psychoacoustics and employs methods of psychophysics. In different industries, loudness may have different meanings and different measurement standards. Some definitions, such as ITU-R BS.1770 refer to the relative loudness of different segments of electronically reproduced sounds, such as for broadcasting and cinema. Others, such as ISO 532A (Stevens loudness, measured in sones), ISO 532B (Eberhard Zwicker, Zwicker loudness), DIN 45631 and ASA/ANSI S3.4, have a more general scope and are often used to characterize loudness of environmental noise. More modern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
A-weighting
A-weighting is a form of frequency weighting and the most commonly used of a family of curves defined in the International standard IEC 61672:2003 and various national standards relating to the measurement of sound pressure level. A-weighting is applied to instrument-measured sound levels in an effort to account for the relative loudness perceived by the human ear, as the ear is less sensitive to low audio frequencies. It is employed by arithmetically adding a table of values, listed by octave or third-octave bands, to the measured sound pressure levels in dB. The resulting octave band measurements are usually added (logarithmic method) to provide a single A-weighted value describing the sound; the units are written as dB(A). Other weighting sets of values – B, C, D and now Z – are discussed below. The curves were originally defined for use at different average sound levels, but A-weighting, though originally intended only for the measurement of low-level sounds (aro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weighting Curve
A weighting curve is a graph of a set of factors, that are used to 'weight' measured values of a variable according to their importance in relation to some outcome. An important example is frequency weighting in sound level measurement where a specific set of weighting curves known as A-, B-, C-, and D-weighting as defined in IEC 61672 are used. Unweighted measurements of sound pressure do not correspond to perceived loudness because the human ear is less sensitive at low and high frequencies, with the effect more pronounced at lower sound levels. The four curves are applied to the measured sound level, for example by the use of a weighting filter in a sound level meter, to arrive at readings of loudness in phons or in decibels (dB) above the threshold of hearing (see A-weighting). Weighting curves in electronic engineering, audio, and broadcasting Although A-weighting with a slow RMS detector, as commonly used in sound level meters is frequently used when measuring noise in a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weber–Fechner Law
The Weber–Fechner laws are two related scientific law, scientific laws in the field of psychophysics, known as Weber's law and Fechner's law. Both relate to human perception, more specifically the relation between the actual change in a physical Stimulus (physiology), stimulus and the perceived change. This includes stimuli to all senses: vision, hearing, taste, touch, and smell. Ernst Heinrich Weber states that "the minimum increase of stimulus which will produce a perceptible increase of sensation is proportionality (mathematics), proportional to the pre-existent stimulus," while Gustav Fechner's law is an inference from Weber's law (with additional assumptions) which states that the intensity of our sensation increases as the logarithm of an increase in energy rather than as rapidly as the increase. History and formulation of the laws Both Weber's law and Fechner's law were formulated by Gustav Fechner, Gustav Theodor Fechner (1801–1887). They were first published in 18 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sone
The sone () is a unit of loudness, the subjective perception of sound pressure. The study of perceived loudness is included in the topic of psychoacoustics and employs methods of psychophysics. Doubling the perceived loudness doubles the sone value. Proposed by Stanley Smith Stevens in 1936, it is not an SI unit. Definition and conversions According to Stevens' definition, a loudness of 1 sone is equivalent to 40 phons (a 1 kHz tone at 40 dB SPL). The phons scale aligns with dB, not with loudness, so the sone and phon scales are not proportional. Rather, the loudness in sones is, at least very nearly, a power law function of the signal intensity, with an exponent of 0.3. With this exponent, each 10 phon increase (or 10 dB at 1 kHz) produces almost exactly a doubling of the loudness in sones. : At frequencies other than 1 kHz, the loudness level in phons is calibrated according to the frequency response of human hearing, via a set of e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phon
The phon is a logarithmic unit of loudness level for tones and complex sounds. Loudness is measured in sones, a linear unit. Human sensitivity to sound is variable across different frequencies; therefore, although two different tones may present an identical sound pressure to a human ear, they may be psychoacoustically perceived as differing in loudness. The purpose of the phon is to provide a logarithmic measurement (like decibels) for perceived sound magnitude, while the primary loudness standard methods result in a linear representation. A sound with a loudness of 1 sone is judged equally loud as a 1 kHz tone with a sound pressure level of 40 decibels above 20 micropascals. The phon is psychophysically matched to a reference frequency of 1 kHz. In other words, the phon matches the sound pressure level ( SPL) in decibels of a similarly perceived 1kHz pure tone. For instance, if a sound is perceived to be equal in intensity to a 1kHz tone with an SPL ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Limen
In physiology, psychology, or psychophysics, a limen or a liminal point is a sensory threshold of a physiological or psychological response. Such points delineate boundaries of perception; that is, a limen defines a sensory threshold beyond which a particular stimulus becomes perceivable, and below which it remains unperceivable. Liminal, as an adjective, means situated at a sensory threshold, hence barely perceptible. Subliminal means below perception. The absolute threshold is the lowest amount of sensation detectable by a sense organ. See also * Just noticeable difference (least perceptible difference) * Threshold of pain, the boundary where perception becomes pain * Weber–Fechner law The Weber–Fechner laws are two related scientific law, scientific laws in the field of psychophysics, known as Weber's law and Fechner's law. Both relate to human perception, more specifically the relation between the actual change in a physica ... (Weber's law) References Physiology ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exposure Action Value
An Exposure Action Value (EAV) or Action Value (AV) is a limit set on occupational exposure to noise where, when those values are exceeded, employers must take steps to monitor the exposure levels. These levels are measured in decibels. The American Occupational Safety and Health Administration (OSHA) set the EAV to 85 dB(A). When the eight-hour time-weighted average (TWA) reaches 85 dB(A), employers are required to administer a continuing, effective hearing conservation program. The program consists of monitoring, employee notification, observation, an audiometric testing program, hearing protectors, training programs, and record-keeping requirements. Purpose The purpose of the EAV is to ensure that employees are not suffering from high levels of noise exposure. OSHA requires employers to take steps to reduce exposure levels when the TWA reaches 90 dB(A). The EAV is to ensure that the exposure levels do not reach 90 dB(A) or more. It is also to ensure that employ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dolorimeter
A dolorimeter is an instrument used to measure pain threshold and pain tolerance. Dolorimetry has been defined as "the measurement of pain sensitivity or pain intensity". Dolorimeters apply steady pressure, heat, or electrical stimulation to some area, or move a joint or other body part and determine what level of heat or pressure or electric current or amount of movement produces a sensation of pain. Sometimes the pressure is applied using a blunt object. History In 1940, James D. Hardy, Harold G. Wolff and Helen Goodell of Cornell University introduced the first dolorimeter as a method for evaluating the effectiveness of analgesic medications. They did their work at New York Hospital. They focused the light of a 100 watt projection lamp with a lens on an area of skin that had been blackened to minimize reflection. They found that most people expressed a pain sensation when the skin temperature reached 113 °F (45 °C). They also found that after the skin temperature r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Absolute Threshold Of Hearing
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.Durrant J D., Lovrinic J H. 1984. ''Bases of Hearing Sciences''. Second Edition. United States of America: Williams & WilkinsGelfand S A., 2004. ''Hearing an Introduction to Psychological and Physiological Acoustics''. Fourth edition. United States of America: Marcel Dekker The absolute threshold is not a discrete point and is therefore classed as the point at which a sound elicits a response a specified percentage of the time. The threshold of hearing is generally reported in reference to the RMS sound pressure of 20 micropascals, i.e. 0 dB SPL, corresponding to a sound intensity of 0.98 pW/m2 at 1 atmosphere and 25 °C. It is approximately the quiet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sound Pressure Level
Sound pressure or acoustic pressure is the local pressure deviation from the ambient (average or equilibrium) atmospheric pressure, caused by a sound wave. In air, sound pressure can be measured using a microphone, and in water with a hydrophone. The International System of Units, SI unit of sound pressure is the Pascal (unit), pascal (Pa). Mathematical definition A sound wave in a transmission medium causes a deviation (sound pressure, a ''dynamic'' pressure) in the local ambient pressure, a ''static'' pressure. Sound pressure, denoted ''p'', is defined by p_\text = p_\text + p, where * ''p''total is the total pressure, * ''p''stat is the static pressure. Sound measurements Sound intensity In a sound wave, the complementary variable to sound pressure is the particle velocity. Together, they determine the sound intensity of the wave. ''Sound intensity'', denoted I and measured in Watt, W·Metre, m−2 in SI units, is defined by \mathbf I = p \mathbf v, where * ''p'' is th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
