468

468

What is ITU-R 468?

ITU-R 468 (originally defined in CCIR recommendation 468-4, therefore formerly also known as CCIR weighting; sometimes referred to as CCIR-1k) is a standard relating to noise measurement, widely used when measuring noise in audio systems.

What is 468 a-weighting?

It is important to realise that the 468 specification covers both weighted and unweighted (using a 22 Hz to 22 kHz 18 dB/octave bandpass filter) measurement and that both use a very special quasi-peak rectifier with carefully devised dynamics (A-weighting uses RMS detection for no particular reason ).

What is the difference between 468 and a-weighted noise measurements?

Dependent on spectral content, 468-weighted measurements of noise are generally about 11 dB higher than A-weighted, and this is probably a factor in the recent trend away from 468-weighting in equipment specifications as cassette tape use declines.

What is CCIR 468-4?

Later versions up to CCIR 468-4 differed only in minor changes to permitted tolerances. This standard was then incorporated into many other national and international standards (IEC, BSI, JIS, ITU) and adopted widely as the standard method for measuring noise, in broadcasting, professional audio, and Hi-Fi specifications throughout the 1970s.

What is ITU-R 468?

ITU-R 468 (originally defined in CCIR recommendation 468-4, therefore formerly also known as CCIR weighting; sometimes referred to as CCIR-1k) is a standard relating to noise measurement, widely used when measuring noise in audio systems.

How does The R468 function work?

This project consists of a sole function named r468 (). The function takes a frequency value and returns a weighted gain value. For weightening, the ITU-R BS.468-4 standard and the SMPTE RP 2054:2010 recommended practice are followed. The math for this project is taken from Wikipedia (as of 2019-08-08): More infos on the project page at PyPI.

What is 468 a-weighting?

It is important to realise that the 468 specification covers both weighted and unweighted (using a 22 Hz to 22 kHz 18 dB/octave bandpass filter) measurement and that both use a very special quasi-peak rectifier with carefully devised dynamics (A-weighting uses RMS detection for no particular reason ).

What is CCIR 468-4?

Later versions up to CCIR 468-4 differed only in minor changes to permitted tolerances. This standard was then incorporated into many other national and international standards (IEC, BSI, JIS, ITU) and adopted widely as the standard method for measuring noise, in broadcasting, professional audio, and Hi-Fi specifications throughout the 1970s.

What is a-weighting in noise measurement?

The most common weighting that is used in noise measurement is A-Weighting. Like the human ear, this effectively cuts off the lower and higher frequencies that the average person cannot hear. Defined in the sound level meter standards (IEC 60651, IEC 60804, IEC 61672, ANSI S1.4), a graph of the frequency response can be seen to the right.

What is the difference between 468 and a-weighted noise measurements?

Dependent on spectral content, 468-weighted measurements of noise are generally about 11 dB higher than A-weighted, and this is probably a factor in the recent trend away from 468-weighting in equipment specifications as cassette tape use declines.

What is the best weighting for noise measurement?

The most common weighting that is used in noise measurement is A-Weighting. Like the human ear, this effectively cuts off the lower and higher frequencies that the average person cannot hear.

What is frequency weighting in a sound level meter?

The frequency weightings used in sound level meters are often related to the response of the human ear, to ensure that the meter is measuring pretty much what you actually hear. It is extremely important that sound level measurements are made using the correct frequency weighting - usually A-weighting.

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