SV Time-Varying Loudness VI

SV Time-Varying Loudness VI

Owning Palette: Sound Quality VIs

Requires: Sound and Vibration Toolkit

Computes time-varying loudness of the sound pressure signal from a time-varying 1/3 octave band spectrum.

This VI calculates the time-varying loudness in compliance with DIN 45631.

Details  Example

SV Time-Varying Loudness (Intensity)

	reset specifies if the VI post-masking temporal filters need to be reset (TRUE) or not reset (FALSE). The default is FALSE. The filters are automatically reset the first time this VI runs.
	diffuse field specifies if the sound field is diffuse (TRUE) or a free field (FALSE). The default is free field (FALSE).
	sound pressure signal [Pa] specifies the sound pressure signal in Pascals. This signal keeps track of the timing of the waveform and the values the waveform contains. t0 specifies the start time of the waveform. dt specifies the time interval in seconds between data points in the waveform. Y specifies the data values of the waveform.
	error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
	specific loudness [Sones/Bark] returns the specific loudness at the critical band rate. The critical band rate is in units of bark. A bark is the unit of measurement for critical band rate. A bark, a pure tone represented as a masking curve, produces a plot consistent with frequency and more accurately than linear or logarithmic plots. The bark scale ranges from 1 to 24, resulting in 24 barks, or cumulative critical bands, from 0 to 16 kHz.
	time-varying loudness [Sones] returns the time-varying loudness from a 1/3 octave spectrum. t0 returns the trigger time of the waveform. dt returns the time interval in seconds between data points in the waveform. Y returns the data values of the waveform.
	offset and multipliers identifies the amount the waveform shifted. t0 and delta t [s] returns the minimum value of the time segment and the increment. t0 returns the minimum value of the time segment expressed in seconds. delta t returns the time increment expressed in seconds. y0 and delta y [Bark] returns scaling information for the y-axis. y0 returns the minimum value of the y-axis. delta y returns the increment for the y-axis.
	loudness info returns information about the loudness measurement. x-axis units returns the units of the x-axis. 0 Frequency—The number of occurrences of a repeating event during a period. 1 Critical band—The smallest band of frequencies around a given frequency. 2 Critical band rate—The frequency scale used in describing characteristics of the human hearing system. x-axis unit label returns the label of the x-axis. y-axis units returns the units of the y-axis. 0 Band power 1 Level 2 Loudness 3 Sharpness 4 Roughness 5 Fluctuation strength 6 Tonality y-axis unit label returns the label of the y-axis. data attributes returns information about the sound quality measurements this VI analyzes.
	error out contains error information. This output provides standard error out functionality.

SV Time-Varying Loudness Details

The SV Time-Varying Loudness VI measures the 1/3 octave spectrum using exponential averaging with a 2 ms time constant, combines the fractional-octave bands into critical bands, and applies temporal and spectral masking. The VI returns the result as the specific loudness versus critical band rate, and then integrates the specific loudness and applies temporal post-masking filters to measure the time-varying loudness. National Instruments recommends running the SV Time-Varying Loudness VI within a data acquisition loop because the VI processes successive 1/3 octave spectra of 2 ms blocks of sound pressure data.

Example

Refer to the Read Time Waveforms with Records (UFF File) VI in the labview\examples\Sound and Vibration\UFF58 directory for an example of using the SV Time-Varying Loudness VI.