Tone-on-tone masking can be detected through beating and combination tones alone

Evidence

A pure tone – a sinusoid with fixed frequency – causes a masking effect similar to that of narrowband noise. However, due to the non-linear processing in hearing, in the presence of a second test tone, called the probe tone, close to the first tone (the masker tone) some beating and combination tones are also perceived. Beats are the periodic changes in the amplitude of the signal, which may be audible as roughness or fluctuations, as will be explained in Chapter 11. Thus, the presence of a probe tone with a tone masker can be detected with lower amplitudes than with a narrow bandnoise masker, as shown in Figure 9.8. In many cases, the probe tone itself is not audible, the listeners perceive only the beating or the combination tones (Fastl and Zwicker, 2007; Wegel and Lane, 1924). — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1006

Categorization

• DEFINE: Explains what beats are in context.
• corroborated: 2 independent passages support this claim — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1006