Pitch mode is completely different from the others multitone mode. It does not take into account the target’s conductivity. The strength of the signal generates an audio signal that varies both in amplitude and height (the audio frequency).
This means that a more distant target will generate a low-pitched, weak sound whereas a closer target will generate a high-pitched, strong sound.
Pitch mode gives signals particular dynamism and can be useful for locating targets.
It also makes the detector seem more reactive. However, it does not fundamentally affect reactivity, just the audio.