Sound Quality Analyzer conducts Fluctuation Strength Analysis on audio WAV files.
Fluctuation Strength (vacil) – A measure of the low frequency (<20Hz) modulation within a signal. When modulations are less than 20 Hz, the human ear can perceive the individual modulations as single events. The ear is most sensitive to these modulations at a frequency of around 4 Hz, so the sensitivity of the metric peaks at this modulation frequency. Values for Fluctuation Strength are typically less than 1 vacil and may be expressed in centivacils. Fluctuation Strength is not a standardized metric. The SQA uses the Höldrich method of determination of Fluctuation Strength.