Frequency masking between competing instruments is best resolved by ear with manual fader automation rather than by keyed processing alone

Frequency masking occurs when two instruments share the same frequency range simultaneously; the louder one desensitizes the listener to the quieter one at those frequencies. Automated tools like keyed compression or dynamic EQ address the average masking level, but the specific masking interactions in a musical composition depend on the exact pitches being played note-to-note and are too complex for automated processing alone to handle. The engineer must listen to each instrument in context through the entire song, noting specific moments where it disappears into the mix or pokes out too far, and adjusting the fader by tiny amounts at those moments.

Examples

Bass guitar note at C2 (65 Hz) clashes with kick drum at exactly the same moment; manual fader pull of -1 dB on the bass on that beat resolves the masking without affecting the surrounding notes.

Assessment

Explain why keyed compressors and dynamic EQ are insufficient to fully resolve frequency masking in a complex arrangement. Describe what the engineer does instead.