Owning Palette: Sound Level VIs

Requires: Sound and Vibration Toolkit

Computes several sound level measurements including equivalent continuous level (Leq), running Leq sound levels, exponential averaged sound level, and the peak sound level. Wire data to the scaled signal [EU] input to determine the polymorphic instance to use or manually select the instance.

The Sound Level VIs return respective sound pressure levels in dB rms relative to the reference. By default, a sound pressure level of 20 uPa rms is used as the reference for conversion to dB. In contrast, peak and peak-to-peak sound pressure levels are referenced to 20 uPa pk.

Details Example

SVT Sound Level (1 Ch)SVT Sound Level (N Ch)

SVT Sound Level (1 Ch)

integration time specifies the duration, in seconds, over which the running Leq is computed. The default is 1.00 s. integration time is rounded to a duration corresponding to an integer multiple of the duration of a single block of time-domain data.
scaled signal [EU] specifies the scaled signal expressed in the selected engineering units. To obtain a properly scaled signal, you can use the SVL Scale Voltage to EU VI or define a virtual channel in National Instruments Measurement & Automation Explorer (MAX).
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.
measurement selection specifies the desired types of sound level measurements. The default measurement selection is Leq .
Leq specifies if the VI computes the equivalent continuous sound level (Leq) of scaled signal . The default is TRUE.
Running Leq specifies if the VI computes the running equivalent continuous sound level (Leq) of scaled signal . The default is FALSE.
Exponential specifies if the VI computes the exponential averaged sound level of scaled signal based on exponential mode . The default is FALSE.
Peak specifies if the VI computes the peak sound level of scaled signal . The default is FALSE.
exponential mode specifies the exponential averaging mode. The Custom option enables you to specify any positive time constant .
0 Slow t = 1 s
1 Fast (default) t = 125 ms
2 Impulse t = 35 ms rising and 1.5 s falling
3 Custom
time constant specifies the time constant in milliseconds used for exponential averaging if exponential mode is set to Custom . In all other cases, this parameter is ignored. The default is 125.00 ms.
error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
restart averaging specifies if the selected averaging process has to be restarted. The default is FALSE. When you call this VI for the first time, the averaging process restarts automatically.
exp avg sound level [dB EU] returns the exponential averaged sound level expressed in decibels. exp avg sound level [dB EU] has been decimated already to reduce the number of level measurement to log, process, and display.
Leq sound level [dB EU] returns the equivalent continuous sound pressure level (Leq) expressed in decibels.
running Leq sound level [dB EU] returns the running equivalent continuous sound level (Leq) in decibels.
peak sound level [dB pk EU] returns the peak sound level expressed in decibels.
error out contains error information. This output provides standard error out functionality.
unit label returns the selected engineering units.

SVT Sound Level (N Ch)

integration time specifies the duration, in seconds, over which the running Leq is computed. The default is 1.00 s. integration time is rounded to a duration corresponding to an integer multiple of the duration of a single block of time-domain data.
scaled signals [EU] specifies the scaled signals expressed in the selected engineering units. To obtain a properly scaled signal, you can use the SVL Scale Voltage to EU VI or define a virtual channel in National Instruments Measurement & Automation Explorer (MAX).
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.
measurement selection specifies the desired types of sound level measurements. The default measurement selection is Leq .
Leq specifies if the VI computes the equivalent continuous sound level (Leq) of scaled signal . The default is TRUE.
Running Leq specifies if the VI computes the running equivalent continuous sound level (Leq) of scaled signal . The default is FALSE.
Exponential specifies if the VI computes the exponential averaged sound level of scaled signal based on exponential mode . The default is FALSE.
Peak specifies if the VI computes the peak sound level of scaled signal . The default is FALSE.
exponential mode specifies the exponential averaging mode. The Custom option enables you to specify any positive time constant .
0 Slow t = 1 s
1 Fast (default) t = 125 ms
2 Impulse t = 35 ms rising and 1.5 s falling
3 Custom
time constant specifies the time constant in milliseconds used for exponential averaging if exponential mode is set to Custom . In all other cases, this parameter is ignored. The default is 125.00 ms.
error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
restart averaging specifies if the selected averaging process has to be restarted. The default is FALSE. When you call this VI for the first time, the averaging process restarts automatically.
exp avg sound levels [dB EU] returns the exponential averaged sound levels expressed in decibels. exp avg sound levels [dB EU] has been decimated already to reduce the number of level measurement to log, process, and display.
Leq sound levels [dB EU] returns the equivalent continuous sound pressure levels (Leq) expressed in decibels.
running Leq sound levels [dB EU] returns the running equivalent continuous sound levels (Leq) in decibels.
peak sound levels [dB EU] returns the peak sound level expressed in decibels.
error out contains error information. This output provides standard error out functionality.
unit labels returns the selected engineering units for each channel.

SVT Sound Level Details

Each measurement is returned as a waveform. Use t0 from the waveform as the start time for the measurement.

This VI complies with ANSI S1.42-2001 (R2006), ANSI S1.43-1997 (R2007), IEC 61672-1:2002, and JIS C 1509-1:2005 standards. Each instance of this VI maintains its own state; use the N Channel instance of this VI to process an array of channels. This VI operates on time-continuous data; it resets on a discontinuity. scaled signal [EU] should have a zero DC component. You can attenuate the DC component with hardware AC-coupling filters and with software high-pass filters Example

Refer to the Sound Level Meter (DAQmx) VI in the labview\examples\Sound and Vibration\Sound Level Measurements directory for an example of using the SVT Sound Level VI.

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