Creates a new Data Block of Acoustic Intensity measurements from time waveforms or a Cross spectrum calculated from data acquired with a two-microphone Acoustic Probe
Four-microphone data (taken with 3 Responses & 1 Reference) can also be used with this command.
When this command is executed, a dialog box is opened.
If Time Responses is chosen as the Data Source, all of the currently open Data Blocks with time waveforms in them are listed in the dialog box.
The Roving waveforms must be identified as (Output or Both) in the Input Output column of the M#s spreadsheet.
The Reference (fixed) waveform must be identified as (Input or Both) in the Input Output column of the M#s spreadsheet.
Acoustic Intensity is calculated from time waveforms using spectrum averaging.
See Spectrum Averaging in the Signal Processing Commands chapter for details.
If Cross Spectra is chosen as the Data Source, all of the open Data Blocks with Cross Spectrua in them are listed in the dialog box.
Acoustic Intensity is calculated from the Cross spectrum between a pair of microphone responses with the formula,
where:
Air density is calculated from the air pressure and temperature values.
Both SPL and P-I Index measurements can also be calculated at the same time as Acoustic Intensity by checking these selections in the Calculate Intensity dialog box.
See the Acoustics | Calculate | SPL or P-I Index commands for details.