Sound Mixes allow you to set the EQ Settings (Equalizer Settings) and modify Volume and Pitch properties of Sound Classes.
Multiple Sound Mixes can be active at the same time, all contributing to the overall audio effect. You can Push (Activate) or Pop (Deactivate) Sound Mixes directly inside a Blueprint with the Push Sound Mix Modifier and Pop Sound Mix Modifier nodes or activate them passively whenever a sound with a given Sound Class is playing within a specified threshold.
However, the Push/Pop method can become very complex quickly if you have a large number of mixes you are trying to switch between. This is where the Set Sound Mix Class Override Blueprint Node comes into play. It can set an active Sound Mix to use any Sound Class you have, and interpolate between its current Sound Class and the new Sound Class over time.
Then you can set the Sound Mix back to its original setting by using the Clear Sound Mix Class Override.
Within the Sound Mix asset itself, which can be opened by Double-Clicking the asset in the Content Browser, several properties exist.
You can specify EQ Settings for the mix to adjust the high, middle, and low frequencies and gains. As the EQ Settings of multiple Sound Mixes cannot be combined, the EQ Priority allows you to control which active mix's properties are applied at any given time.
Inside the Sound Classes section, you set which Sound Classes are to be affected by the mix. For each Sound Class you can set the Volume or Pitch adjusters, set if the mix settings are to be applied to Child Classes, or modify the VoiceCenterChannelVolume.
The Sound Mix section allows you to specify how the Sound Mix properties are applied or removed. Delay indicates how long before the mix properties should begin being applied. Fade in Time and Fade out Time specify how quickly to transition from no effect to the specified properties. Duration allows a pushed Sound Mix to automatically pop itself after the specified duration. A value of -1 indicates to never automatically pop and passively applied Sound Mixes will not automatically pop.