ISO 532-2-2017 pdf free download.Acoustics Methods for calculating loudness Part 2:Moore-Glasberg method
Acoustique — Méthode de calcul d’isosonie — Partie 2: Méthode Moore-Glasberg.
level is determined shall also be specified. Within the procedure, the spectra of bands of noise are approximated by a series of discrete sinusoidal components. When the bandwidth of the noise exceeds 30 Hz, the components are spaced at 10 Hz intervals, and the level of each component is set 10 dB higher than the spectrum level at the corresponding frequency. When the bandwidth of the noise is less than 30 Hz, the components are spaced at 1 Hz intervals, and the level of each component is set equal to the spectrum level at the corresponding frequency.
EXAMPLE I A band of white noise extending from 200 Hz to 500 Hz with a spectrum level of 50 d13 would be approximated by sinusoidal components with frequencies 205 Hz, 215 Hz, 225 Hz, 235 Hz …. 475 Hz, 485 Hz, 495 Hz, each component having a sound pressure level of 60 dB.
EXAMPLE 2 A band of pink noise havinglowerand upper cut-off frequencies of 100 lIz and 115Hz, respectively, with a spectrum level of 65 dB would be approximated by sinusoidal components with frequencies 101 Hz, 102 Hz, 103 Hz, 104 Hz …. 113 Hz, 114 Hz, 115 Hz, with the components having sound pressure levels Increasing progressively from 64,7 dB at 101 Hz to 65,3 dB at 115 Hz.
NOTE The spacing of the components (10 liz as in Example 1 or 1 Hz as in Example 2) is not a property of the input signal. The 1 Hz spacing is used to ensure sufficient accuracy in the computation of loudness when the bandwidth of the spectrum of the signal is narrow, i.e. less than 30 Hz. For signals with wider bandwidth, I.e. 30 Hz or greater, then a 10 Hz spacing will result in sufficient accuracy for the purpose of the computation of loudness.
5.4 Mixture of discrete sinusoidal components and bands of pink or white noise
For the case of mixtures of sounds, which each have a spectrum consisting of discrete sinusoidal components, £2 is applied for each discrete sinusoidal component that the mixed sound comprises. For the case of a mixture of bands of pink or white noise, the spectrum of each component of the mixture can be specified exactly using 5.3. This method is mainly applicable to synthetic signals, although it could be applicable to signals with strong line components in a noise background.
5.5 Sound specified in terms of the sound pressure levels in 29 adjacent one-third- octave bands
The nominal centre frequencies of the 29 adjacent one-third-octave bands are as defined by IEC 61 260- 1:20 14 within the range 25 lIz to 16 000 Hz. Within each band, the spectrum is assumed to be flat, and, as described for noise bands in 53. the spectrum is approximated as a series of sinusoidal components spaced at 10 Hz intervals or (for centre frequencies of 125 Hz and below) at 1 Hz intervals. The level of each component is calculated as follows. Let the width of a one-third-octave band at a given centre frequency be W (e.g. 230 Hz for a centre frequency of 1 000 Hz). The sound pressure level in that band, LT, Is converted to the spectrum level In that band as LT — lOlg(W/1 Hz) dB. The level of each component in the approximation Is then set 10 dB above the spectrum level, i.e. to LT — lOlg(W/1 Hz) dB + 10 dB.
NOTE The 1/3 octave filters, as defined by IEC 61260—1:2014, to analyse the spectrum of the input signal can have errors in their outputs of up to ± 0,7 dl3.ISO 532-2-2017 pdf free download.