Time Constants and Time Weightings
Fast, Slow, Impulsive and Peak sound levels are extensively used in acoustics
Fast, Slow and Impulse
F : Fast= 125 ms up and down,
S : Slow= 1 second up and down,
I : Impulse= 35 ms while the signal level is increasing or 1,500 ms while the signal level is decreasing.
Peak, True Peak
Peak: to measure the True Peak values of impulsive sound levels a meter must be equipped with a
Peak Detector: a peak detector responds in less than 100µs (microseconds), according to the sound level meter standards. A typical response time is 40µs.
Peak Hold: peak detection process retaining the 'true' maximum value of a signal.
Peak Level: maximum instantaneous level of stated kind that occurs during a stated time interval.
Peak Sound Level: twenty times the Logarithm to the base ten of the ratio of a peak sound pressure to the reference sound pressure.
Peak Sound Pressure: greatest absolute instantaneous Sound Pressure during a stated measurement period.
Peak-to-Peak: the amplitude difference between the most positive and most negative value in a time waveform, that is, the total Amplitude.
See also Crest Factor and RMS - Root Mean Square.
See also: Noise Dose l Exponential Averaging l Sound Exposure
Page Up l Glossary Search l Certified Instrumentation
This site is maintained by
Gracey & Associates 01234 708835
The Sound and Vibration Instrument Hire and Calibration Specialists
Instrument Hire | Calibration | Standards | Link to us or e-mail us