Sound Intensity Options


  • Speed of Sound
    The speed of sound, in air, can be specified here in units of meters per second (343 m/s, by default).
  • Density of Air
    The density of are can be specified here in units of kilograms per cubic meter (1.21 kg/m^3, by default).
  • Velocity Integration Time Constant
    Acoustic particle velocity is estimated by integrating the difference between the 2 microphones in the intensity probe. The length of the integration is determined by this time constant. Larger values mean more acoustic pressure samples contribute to the current velocity estimate.
  • Frequency Weighting
    SignalScope provides a means of weighting the spectral content of input signals according to standard A and C frequency weighting curves (the Z, or zero, weighting selection does not apply any weighting to the signal). These A and C weighting curves are intended to mimic human perception of loudness at two different loudness levels. The desired frequency weighting can be selected from the segmented control.

Auto Stop Options

  • Auto Stop
    Intensity measurements can be configured to automatically stop after a predetermined amount of time. The elapsed time after which the current measurement will stop can be set in increments of 1 second up to two weeks in duration. When the octave level averaging time is set to ∞, the measurement will continue to average the octave-band results as long as the tool is running, so the auto-stop duration can be used to specify the total averaging time of the measurement.

Octave Options

  • Bandwidth
    The Intensity tool performs either whole-octave-band or third-octave-band measurements with center frequencies recommended by ANSI standards.
  • Averaging Time
    The Intensity tool offers three averaging times for the sound intensity measurement: 1/8s, 1s, and ∞.
    • With 1/8s or 1s, the pressure, velocity, and intensity are calculated over a 1/8 or 1-second time interval, respectively. In this case, the measurement values are updated at those same intervals.
      With ∞, the values are calculated over the entire duration of the measurement.
  • Min/Max Frequency Band
    The range of whole or 1/3-octave frequencies to display and to include in the overall level calculations is determined by the selections for minimum and maximum frequency band.

FFT Options

  • FFT Time/Frequency Resolution
    SignalScope simplifies narrowband (FFT) configuration by allowing you to choose a time or frequency resolution for narrowband spectral analysis. SignalScope then automatically calculates the FFT length required for that frequency resolution at the audio input hardware's current sample rate. It should be noted that in this case, frequency resolution refers to the distance between adjacent spectral lines (or frequency bins) in the spectrum.
  • Min/Max Frequency
    A frequency range can be specified for the narrowband spectrum display. Only values that correspond to frequencies between min and max will be plotted. Only those values will be included when exporting spectral data to a file. The Cursor Peak Track function will operate within the selected frequency range.
  • Averaging
    Successive measurements may be averaged according to the selection of this segmented control. Available average types include: Linear (Stable) and Exponential. Linear averaging weights all measurements equally. Exponential averaging applies an exponential weighting such that more recent measurements contribute to the current average value more than older measurements. When linear averaging is selected, the analyzer will automatically stop after the specified number of spectra have been averaged.
  • Averages
    The number of measurements to include in the current average is specified in the Averages text box. When linear averaging is the selected average type, the analyzer will automatically stop after the specified number of measurements have been included in the average. Exponential averaging allows the analyzer to continue running even after the specified number of measurements have been processed. The exponential average can be thought of as including only the most recent N (time-exponential-weighted) measurements, where N is the specified number of averages.

Data Export

  • Current Location
    When this option is enabled, the latitude, longitude, and altitude at the time of the measurement will be included in exported data files. Horizontal and vertical accuracy (in meters) will also be included.