HOW IT WORKS
Technically speaking, our AccessiblePeakMeter is an audio processor, much like the digital audio effects employed in audio production. However, instead of transforming the input audio signal in some way, our AccessiblePeakMeter lays an additional sound on top of it, which represents the level of the signal.
The way the sound is added depends on the sonification mode the plug-in is set to. There are two different modes: clipping and continuous. Let's see them more in detail.
When in clipping mode the plug-in emits a beep sound when the input audio level goes past a threshold - its like the red light that blinks on visual peak level meters when clipping happens. You can set the threshold value in the range from -60 dB to +6 dB. So for example if you want to be sure your audio doesn't clip, just set the threshold to 0 dB and you will hopefully hear no beep. If your audio does clip instead, you'll hear the beep exactly at the point in time where the clipping occurs. Another case in which the clipping could be useful is when one wants to leave some headroom for the mastering phase: just crank the threshold to, say, -3dB and repeat the same process. You can also adjust the threshold as your DAW plays, for a total dynamic inspection.
When you try out the clipping mode, you'll notice that the plug-in beeps with different tones. This is because pitch variation is used to inform you of how much your audio signal exceeds the threshold. That is, the beep starts with a classic A4 (440Hz) tone and is then raised half tone for each dB of difference between the threshold and the audio signal level.
For example: if the signal is up to 1 dB louder than the threshold, you'll hear the A4; if it is more than 1 dB and up to 2 dB louder, you'll hear an A#4; louder than 2 dB and up to 3 dB, will raise it to a B4 and so on. The maximum difference detected has a cap at 12 dB, which means that all differences above 12 dB will still be rendered as an A5 tone, one octave higher than the 1 dB tone.
Finally, the sonification works in stereo. The tones you hear on the left and right channels are not necessarily the same because they represent respectively the left and right channel of the input audio. So for example if your audio exceeds the threshold only on the left channel, you'll hear the beep only on the left; if the left and right channels of the input audio exceed of a different amount of loudness, you'll hear two different tones on the left and on the right.
In continuous, the plug-in behaves like a visual level meter bar that goes up and down to give you an overall idea of the level of the audio signal.
In fact, it is a sonification that represents the level of the audio signal by pitch-modulating a continuous sine wave. The modulation ranges from 0 to 2000 Hertz and it is linear to the level value in dB.
If your audio has very high dynamic range, the plug-in will produce a very higly modulated sine wave, going from low tones to high tones with very high frequency. On the other hand if your audio is very compressed and chunky, you'll hear a relatively stable and unvarying sine tone.
The continuous sonification is also in stereo. You will hear a nice concert for two sine waves, if the left and right channels of your audio content are very different from each other!