A cool, interactive calculation utility (download here) for handling common acoustical and decibel calculations including:
YouTube Demo: noiseLab Calculator Overview
- Sum multiple sound levels, also time-weighted
- Add an arbitrary number of equal level sound sources
- Subtract dB/Correct for background noise
- dB to Pascal and Microphone sensitivity in dB or mV/Pascal
- dB to Volts to Percentage
- Free field propagation
and noiseLAB Calcultor is unique because most computations work forward and backwards, i.e. key in any field and the other fields are computed automatically.
Weighting of octave or 1/3 octave spectra:
Import a spectrum from spreadsheet or manually enter it and convert forwards and backwards from any weighting (A,B,C, Lin) to any other weighting.
YouTube Demo video: A B C weighting of imported 1/3 Octave Spectrum
Speed of Sound/Doppler shift:
Plot the frequency shift of sound from a passing train or car measured at a given distance from the track or road. Compute the speed of sound for different temperatures, and also get the wavelength, period, etc. at a given frequency. And yes, it works with both metric and English units.
YouTube Demo: Speed of Sound and Doppler Shift
Octave and 1/3 octave Filter Characteristics and Error Bands
Show the filter shape for filters at any center frequency, along with with its bandwidth and corner frequencies.
Show the Error bands for random signal analysis as function of center frequency, averaging time or desired accuracy at a selected frequency.