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Loudness (FPScript)

21.09.2021

Calculates the loudness of a sound signal.

Syntax

Loudness(DataSet, [ Algorithm = LOUDNESS_ISO_532_1 ], [ SoundField = LOUDNESS_DIFFUSE ], [ InputType = LOUDNESS_INPUT_SPECTRUM ], [ SkipTime = 0.0 s ], [ CalibrationValue = 0.0 dB ] [ , Result = LOUDNESS_RESULT_LOUDNESS ])
or
Loudness(Signal, ReferenceSignal, CalibrationLevel, [ Algorithm = LOUDNESS_ISO_532_1 ], [ SoundField = LOUDNESS_DIFFUSE ], [ InputType = LOUDNESS_INPUT_SOUNDPRESSURE_STAT ], [ SkipTime = 0.0 s ] [ , Result = LOUDNESS_RESULT_LOUDNESS ])

 

The syntax of the Loudness function consists of the following parts:

Part

Description

DataSet

The input data set with the spectra of the stationary sound, the measured voltages of the stationary sound, the measured voltages of the time-varying sound, the measured sound pressure levels of the stationary sound or the measured sound pressure levels of the time-varying sound.

Permitted data structures are data series, data matrix, signal und signal series. All numeric data types are permitted.

If the argument is a list, then the function is executed for each element of the list and the result is also a list.

Signal

The input data set with the measured voltages of the stationary sound, the measured voltages of the time-varying sound, the measured sound pressure levels of the stationary sound or the measured sound pressure levels of the time-varying sound.

Permitted data structures are signal und signal series. All numeric data types are permitted.

For the X component additional restrictions do apply.

For complex data types the absolute value is formed.

If the argument is a list, then the function is executed for each element of the list and the result is also a list.

ReferenceSignal

The reference signal with which the input signal is calibrated.

Permitted data structures are signal. All numeric data types are permitted.

For the X component additional restrictions do apply.

For complex data types the absolute value is formed.

If the argument is a list, then the function is executed for each element of the list and the result is also a list.

CalibrationLevel

The reference signal sound pressure level generated by the calibrator.

Permitted data structures are scalar value. All numeric data types are permitted.

If the argument is a list, then the first element in the list is taken. If this is also a list, then the process is repeated.

Algorithm

The algorithm for calculating loudness.

The argument Algorithm can have the following values:

Constant

Meaning

LOUDNESS_STEVENS

Stevens method (ISO 532 A) (obsolete standard).

LOUDNESS_ZWICKER

Zwicker method (ISO 532 B) (obsolete standard).

LOUDNESS_ISO_532_1

Zwicker method (ISO 532-1).

LOUDNESS_ISO_532_2

Moore-Glasberg method (ISO 532-2).

If the argument is a list, then the first element in the list is taken. If this is also a list, then the process is repeated.

If this argument is omitted, it will be set to the default value LOUDNESS_ISO_532_1.

SoundField

Sound field. The Zwicker method supports the diffuse field and direct field (free field). The Stevens method only supports the diffuse field.

The argument SoundField can have the following values:

Constant

Meaning

LOUDNESS_DIFFUSE

Diffuse sound field.

LOUDNESS_FREE

Direct sound field (free field).

If the argument is a list, then the first element in the list is taken. If this is also a list, then the process is repeated.

If this argument is omitted, it will be set to the default value LOUDNESS_DIFFUSE.

InputType

The input signal type. Specifies how to interpret the DataSet input data set. A microphone sensitivity of 50 mV/Pa handles the conversion between voltage values (V) and sound pressure values (Pa). For more details, see Calibration in Acoustics.

The argument InputType can have the following values:

Constant

Meaning

LOUDNESS_INPUT_SPECTRUM

The input signal is the third octave spectrum (ISO 532 B, ISO 532-1, ISO 532-2) or octave spectrum (ISO 532 A) of the stationary sound. The third octave spectrum must be a data series or a signal with 28 third octave band levels for frequencies between 25 Hz and 12500 Hz (ISO 532 B, ISO 532-1). The third octave spectrum must be a data series or a signal with 29 third octave band levels for frequencies between 25 Hz and 12500 Hz (ISO 532-2). The octave spectrum must be a data series or a signal with 9 octave band levels for frequencies between 31.5 Hz and 8000 Hz (ISO 532 A).

LOUDNESS_INPUT_VOLTAGE_STAT

The input signal is the measured voltage signal of a stationary sound.

LOUDNESS_INPUT_VOLTAGE_VAR

The input signal is the measured voltage signal of a time-varying sound.

LOUDNESS_INPUT_SOUNDPRESSURE_STAT

The input signal is the measured sound pressure signal of a stationary sound.

LOUDNESS_INPUT_SOUNDPRESSURE_VAR

The input signal is the measured sound pressure signal of a time-varying sound.

LOUDNESS_INPUT_SPECTRUM_DICHOTIC

The input signal is the dichotic third octave spectrum of the stationary sound. This is a data matrix or signal series with two columns which represent the laterally different audible signals. In this case, both signals are considered and produce a loudness value. This input type is only supported by the ISO 532-2 method.

LOUDNESS_INPUT_VOLTAGE_DICHOTIC

The input signal is the dichotic voltage signal of a stationary sound. This is a data matrix or signal series with two columns which represent the laterally different audible signals. In this case, both signals are considered and produce a loudness value. This input type is only supported by the ISO 532-2 method.

LOUDNESS_INPUT_SOUNDPRESSURE_DICHOTIC

The input signal is the dichotic presented sound pressure signal of a stationary sound. This is a data matrix or signal series with two columns which represent the laterally different audible signals. In this case, both signals are considered and produce a loudness value. This input type is only supported by the ISO 532-2 method.

If the argument is a list, then the first element in the list is taken. If this is also a list, then the process is repeated.

If this argument is omitted, it will be set to the default value LOUDNESS_INPUT_SPECTRUM.

SkipTime

Time domain to skip at the start of the stationary input signal. This value is ignored in the case of time-varying signals.

Permitted data structures are scalar value. All numeric data types are permitted. The argument is transformed to the unit s.

The value must be greater or equal to 0 s.

If the argument is a list, then the first element in the list is taken. If this is also a list, then the process is repeated.

If this argument is omitted, it will be set to the default value 0.0 s.

CalibrationValue

Calibration value used to factor in the microphone sensitivity in dB. A calibration value of 0 dB is equivalent to a microphone sensitivity of 50 mV/Pa or level output of dB over 1 µV for voltages. If the calibration value is omitted, 0 dB is used. The calibration value can be calculated from the AcousticCalibration function.

Permitted data structures are scalar value. All numeric data types are permitted. The argument is transformed to the unit dB.

If the argument is a list, then the first element in the list is taken. If this is also a list, then the process is repeated.

If this argument is omitted, it will be set to the default value 0.0 dB.

Result

Result type. Specifies which result the function returns.

The argument Result can have the following values:

Constant

Meaning

LOUDNESS_RESULT_LOUDNESSOVERTIME

The result from the function is the loudness over time. This result can only be selected for time-varying sound signals.

LOUDNESS_RESULT_LOUDNESS

The result from the function is the overall loudness (sone) for stationary sound signals and the percentile loudness N5 for time-varying sound signals.

LOUDNESS_RESULT_LOUDNESSLEVEL

The result from the function is the loudness level (phon). Overall loudness is used for calculations with stationary signals. For time-varying signals on the other hand, the percentile loudness N5 is used.

LOUDNESS_RESULT_SPECIFICLOUDNESS

The result from the function is the specific loudness in the sone/Bark unit as a Y component. The X component in the case of stationary signals contains the tonality in Bark. In time-varying signals the X component contains the time in s and the Z component contains the tonality in Bark.

LOUDNESS_RESULT_LOUDNESSMAX

The result from the function is the maximum overall loudness (sone). In the case of stationary sound signals the result is identical to overall loudness.

If the argument is a list, then the first element in the list is taken. If this is also a list, then the process is repeated.

If this argument is omitted, it will be set to the default value LOUDNESS_RESULT_LOUDNESS.

Remarks

Loudness can be calculated for stationary and time-varying sound. With the Stevens method, an octave band analysis is performed, whereas with the Zwicker or Moore-Glasberg method, a third octave analysis is used. If the input spectrum does not match the required number of levels, it will be filled with zeros or will be cut off. For signals the level value is assigned to the associated frequency. Alternatively voltage signals or sound pressure signals can be selected as the input variable.

Available in

Option Acoustics

Supported Methods

Standard

Method

Sound field

Dichotic listening

Time-varying signals

Result type

ISO 532-1

Zwicker

Diffuse field/free field

No

Yes

All

ISO 532-2

Moore-Glasberg

Diffuse field/free field

Yes

No

Loudness/loudness level

ISO 532 A

Stevens (obsolete standard)

Diffuse sound field

No

No

Loudness/loudness level

ISO 532 B

Zwicker (obsolete standard)

Diffuse field/free field

No

No

Loudness/loudness level

Observed Standards

Standard

Description

ISO 532-1:2017

Acoustics - Method for calculating loudness. Part 1: Zwicker method

ISO 532-2:2017

Acoustics - Method for calculating loudness. Part 2: Moore-Glasberg method

ISO 532 (ISO 532 A, ISO 532 B)

Acoustics - Method for calculating loudness level.

DIN 45631

Procedure for calculating the loudness level and the loudness from the sound spectrum; E. Zwicker method.

Examples

Loudness(Signal1, LOUDNESS_ISO_532_1, LOUDNESS_DIFFUSE, LOUDNESS_INPUT_SOUNDPRESSURE_STAT)
 

Determines loudness from the stationary sound level signal 'Signal1' according to the Zwicker method. The signal has already been calibrated.

Loudness(Signal1, Reference, 60, LOUDNESS_ISO_532_1, LOUDNESS_FREE, LOUDNESS_INPUT_SOUNDPRESSURE_STAT, 0.2, LOUDNESS_RESULT_LOUDNESSLEVEL)
 

Determines loudness (Zwicker method) from the stationary sound level signal 'Signal1'. The signal is calibrated via a reference signal corresponding to 60 dB. For the calculation 0.2 seconds are skipped at the start.

See Also

AcousticCalibration Function

Sharpness Function

SoundLevel Function

TimeDomainOctaveAnalysis Function

Loudness Analysis Object

Octave Analysis Object

Sound Level Analysis Object

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