The VOG was originally designed to capture the chest resonance of vocalists or voice over artists, enabling them to still have a proximity type effect without having to be so close to the mic, hence the name, VOG, or Voice of God. However, when it was heard on a kick drum and bass, it became clear this would be the go to device to make these instruments sound huge.
The I-VOG lets users sweep a sharp peak resonance from 20 to 300 Hz, while anything below the peak is rolled off at a steep -24dB per octave. This lets users focus on the low end they want, while eliminating low-end mush and unnecessary woofer excursion.
A subharmonic can be the focus, or the fundamental, or upper harmonics. On a kick drum, for example, the overall effect of turning I-VOGs frequency knob sounds like someone is tightening or loosening the drumhead. In a mix, I-VOG allows users to place the bass spectrum instruments so they do not interfere or get in the way of each other.