public void setLowFreqVolume(float lowFreqVolume) {
        if (lowFreqVolume < 0 || lowFreqVolume > 1)
            throw new IllegalArgumentException("Low freq volume must be between 0 and 1");

        this.lowFreqVolume = lowFreqVolume;
        this.updateNeeded = true;
    }
Sets the gain at low frequencies for the High-Pass filter.

@param lowFreqVolume The low-frequency gain value (0.0 to 1.0).
jme3-core/src/main/java/com/jme3/audio/HighPassFilter.java