Frequency masking
Frequency masking is an effect that happens when loud sounds further attenuate quieter sounds that exhibit similar frequencies.1
On-frequency masking creates a bigger effect than off-frequency masking, though off-frequency masking can still mask other signals. The masker must be even louder for off-frequency masking to take the same effect, as shown in the figure below.2
! [[ Maskingpattern.jpg ]]
The figure also shows that low-frequency maskers cause the most wide-band masking.2 With this in mind, Low-frequency boosts can tame harshness.
Instrument pairings that typically mask one another are:
- Kick and bass
- Bass and guitar
- Acoustic guitar and hi-hat
- Electric guitar and electric pianos
- The body of snare and guitar
- Vocals and piano
- BGVs and pads3
Also bear in mind that percussive elements carry less weight due to their lack of sustain. Sustained elements run the risk of masking percussive elements much more. It is better that a percussive element masks a sustained element because it will only do so for a brief moment.4
Frequency masking is not always a bad thing. Sometimes it can help different sounds blend together.3 But if you do want to reduce masking, see How to fix frequency masking.
Due to the Equal loudness curve, monitoring at higher levels results in more masking.5 Another reason to Mix at lower levels to get the midrange right.