Narrow-band noise amplitude fluctuations mask periodic amplitude modulation detection

Evidence

The most important variable in this context seems to be bandwidth. For very small bandwidths, the statistical fluctuation of the amplitude of the narrow-band noise becomes dominantly audible, and thereby strongly disturbs the subjects who are trying to hear periodical amplitude modulations. This is why the just-noticeable degree of amplitude modulation is much larger for narrow bands of noise than for sinusoidal tones, even though the spectral configurations are very similar in the two cases. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1033

For spectral widths of the band-pass noise larger than a critical band, the just-noticeable degree of amplitude modulation decreases. This decrease results from the cooperation of several critical bands. Whether this cooperation can be accounted for by adding up the available variations in a coherent fashion across critical bands, or by some other strategy used by the ear remains unclear. However, all psychoacoustical data relevant to this question show a decrease in the just-noticeable amplitude modulation, with an increase in the number of critical bands involved. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1032

Categorization

Category: Causal Relationships

• XREF: The intrinsic statistical fluctuation of narrow-band noise is a core signal-processing fact; connects to how noise envelopes and detection interplay in psychoacoustics.

Related

• Narrow-band noise’s intrinsic amplitude jitter masks external amplitude modulation detection (similarity 0.93)
• Narrow-band noise keeps a Gaussian amplitude distribution that statistically modulates its perceived sound (similarity 0.89)
• Narrow-band noise self-modulation masks external amplitude modulation (similarity 0.87)
• Wider noise bandwidths decrease detectable amplitude modulation via multi-band cooperation (similarity 0.86)
• Sideband audibility shifts the detection criterion at high modulation frequencies (similarity 0.85)
• Just-noticeable amplitude modulation of narrow-band noise is near 6 percent at high centre frequencies (similarity 0.85)
• White noise shows no sideband-mediated detection ceiling for AM. (similarity 0.85)
• Narrowband noises contain fewer frequencies and show greater amplitude fluctuations than broadband noise. (similarity 0.84)
• Narrow-band noise self-modulates at 0.64 times its bandwidth (similarity 0.84)
• Periodic amplitude fluctuations are perceived as stronger than equivalent random fluctuations. (similarity 0.84)
• Just-noticeable amplitude modulation of noise shrinks from 40% to 6% as bandwidth widens. (similarity 0.84)
• Narrower noise bandwidths produce slower amplitude fluctuation rates (similarity 0.83)
• Narrow-band filters smear signal onset despite resolving harmonics (similarity 0.83)
• Narrow-band noise behaves like a randomly amplitude-modulated pure tone. (similarity 0.83)
• Noise fluctuations within narrow critical bands raise the masking index (similarity 0.83)