A narrow noise band can mask signals multiple octaves away at high stimulus levels.

Evidence

Their data illustrate the frequency selective nature of the ear in that only frequencies near a signal were able to mask it and upward spread of masking, in which low-frequency sounds masked high-frequency sounds greater than the reverse. We can also see substantial nonlinearity: More intense sounds produced greater upward spread of masking. It is impressive how far masking extends for a fairly narrow band of noise, particularly at the high stimulus levels where masking extended multiple octaves! — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 471

Categorization

• XREF: This nonlinear spreading of masking is central to understanding why loud low-frequency sounds drown out speech — relevant to hearing-aid fitting and cocktail-party listening.
• SEED: An essay on why ‘it was so loud I couldn’t hear anything’ is literally true — upward spread of masking means loud bass leaves no auditory room for high-frequency detail.