Scope dependency

The available Advanced View graphs depend on the current scopes.

Press to toggle between different Advanced View graphs.

The first two graphs are available for all scopes.

Multi-function graph

This graph is similar to the Simple View, the only difference being that functions L_W, I_eq and L_eq are displayed simultaneously.

Dynamic Capability graph

This graph presents the Surface pressure-intensity indicator F₂ along with the dynamic capability (L_d) obtained from the last probe calibration or verification.

L_d = ∂_pI0 - K, where K is either 10 dB Precision and Engineering or 7 dB for Survey.

∂_pI0 is the F₂ measured when the probe is exposed to a sound field which is exactly the same for both microphones.

F₂ is defined as the difference between sound pressure level and the level of the average unsigned sound intensity. When calculating F₂, all segments are assumed to have the same area, and the intensity values are thus not weighted by the area. In symbols, F₂ = L_p-L_|I|.

Negative partial power (F₃) graph

This graph presents the Negative partial power indicator F₃. This indicator is almost similar to F₂, but the sound intensity is signed: F₃ = L_p-L_I.

Also here, the intensity values are not weighted by the area of the segments.

One may also evaluate the dynamic capability of the instrument against the F₃ which will then be a stricter requirement.

Extranous Noise graph

The difference between F₃ and F₂ is used to evaluate the level of extranous noise.

The Extraneous Noise warning is issued if the difference is greater than 3 dB.

Field non-uniformity (F₄) graph

The Field non-uniformity indicator F₄ is calculated to evaluate if the number of probe positions is sufficent for the sound field around the source.

The indicator calculates the deviation of a single probe position's sound intensity from the average sound intensity.

F₄ = 1/I · (1/(N-1) Σ (I_i - I)²)^1/2

where i represents a positions index and N is the total number of positions.

The F₄ indicator is used to calculate the Inadequate number of positions warning together with a constant depending on the required accuracy and frequency band and N.

Temporal variability (F₁) graph

The Temporal variability indicator F₁ calculates how much the sound field varies in time based on a single measurement psoition

Consult the Temporal Variability page for more information

F₁ values greater than 0.6 generates the Field not stationary warning.

More information

Getting started with Sound Intensity

Intensity theory

Sound Intensity help index