I’m not certain exactly how the SetPitchMultiplier and SetGlobalPitchModulation blueprint nodes relate to IXAudio2SourceVoice::SetFrequencyRatio, but, when using those 2 blueprint nodes there is no hard limit to the pitch multiplier. However, they only give good results between 0.4 and 2.0 (e.g. a pitch multiplier input of 0.4 results in a pitch that is actually 0.4 times lower, but a pitch multiplier input of 0.001 only results in a pitch that is actually 0.38 times lower).