Two tones sound rough until no single ear filter captures both

Evidence

When two pure tones are played simultaneously, they are not always per­ ceived as two separate pure tones. The discussion relating to Figure 2.7 introducing critical bandwidth in Chapter 2 provides a first example of sounds which in some sense deceive the ear. These two pure tones are only perceived as separate pure tones when their frequency difference is greater than the critical bandwidth. Otherwise they are perceived as a single fused tone which is “rough” or as beats depending on the frequency difference between the two pure tones. — David Howard, Jamie Angus, coustics and Psychoacoustics, 1610 (#complicates, via linked claim)

Categorization

• XREF: connects to: Beats arise when two close frequencies combine in unresolved filters; Frequency separation between two tones systematically shifts fusion, roughness, then resolution; Two tones fuse into one unless their separation exceeds critical bandwidth — David Howard, Jamie Angus, coustics and Psychoacoustics, 1610

Broader Connections

• Frequency separation between two tones systematically shifts fusion, roughness, then resolution #expands (0.85)
• Beats arise when two close frequencies combine in unresolved filters #expands (0.75)
• Two tones fuse into one unless their separation exceeds critical bandwidth #complicates (0.75) — David Howard, Jamie Angus, coustics and Psychoacoustics, 1610