Leq Metering

Introduction

Leq encompasses a set of sound level meter specifications, which are described in detail in the BS EN 61672-1 European Standard.

FLUX:: Analyzer implements the following Leq measurements: time-weighted sound level, time-average sound level and sound exposure level.

Frequency weighting is employed for all measurements, A being the standard and default, although other weightings can be specified if necessary.

The Leq module always measures the audio routed through the Mic channel.

Time-weighted sound level

LA is the root-mean-square sound level obtained after exponential time weighting.

Exponential averaging has the effect of progressively ‘forgetting’ past sample values.

The norm specifies two time-weighting constants:

  • Fast : 125ms
  • Slow: 1s
Note

The corresponding letter symbol is LAF for an A-frequency weighted and F time-weighted sound level, for example.

Time-average sound level

Time-average sound level is basically an RMS meter with frequency-weighting applied.

Sound exposure level

This measures the sound exposure equivalent to a ‘dose’ received for a second.

Note

It is useful for determining the amount of sound pressure to which listeners have been exposed for a certain duration.

This value naturally increases with time. For a constant source level, this value increases in a logarithmic fashion.

Mic. channel Leq setup

Mic. channel Leq setup

Zero ref.

Adjusts the reference point. See RMS for more information.

Weighting

Frequency weighting employed. Can be switched between ANSI standard (A, B, C, D) and none. The default is A.

Time-weighted F

Indicates the time-constant for the Fast time-weighted sound level.

Time-weighted S

Indicates the time-constant for the Slow time-weighted sound level.

Average integration

Sets the integration time for the time-average sound level, between 1s and 14400s (4 hours). Default is 10s.

Main display

Switches the main measurement display from time-average sound level (the default) to sound exposure level.

SPL

SPL reference

This is the reference level of the calibrator’s output, indicated on the device itself or in the corresponding datasheet. A typical value is -94dB.

SPL trim

This is the offset applied to RMS dB values in order to obtain dB SPL readings. It is determined automatically by the calibration procedure.

Calibrate

Press this button after having insert the microphone into the calibrator socket and activated it in order to determine the SPL trim value.

Color

The following settings control the visual aspect of the Leq display.

Font back

Common font background color.

Main level font color. ### Level

Time-weighted F

Fast time-weighted level font color.

Time-weighted S

Slow time-weighted level font color.

Name

Name font color

Unit

Unit display font color.

Freq. weighting

Frequency weighting type display font color.

Font blur

Toggles font blurring on (default) and off.