Widening a sound’s bandwidth beyond one critical band raises perceived loudness at unchanged intensity.

Evidence

Figure 2.16 shows a plot of the subjective loudness perception of a sound at a constant intensity level as a function of the sound’s bandwidth, which illus­ trates this effect. In the cochlea the critical bands are determined by the place at which the peak of the standing wave occurs; therefore all energy within a critical band will be integrated as one overall effect at that point on the basilar membrane and transduced into nerve impulses as a unit. On the other hand, energy which extends beyond a critical band will cause other nerves to fire and it is these extra nerve firings which give rise to an increase in loudness. — David Howard, Jamie Angus, coustics and Psychoacoustics, 653

Categorization

• XREF: Links directly to the ear’s frequency-analyzing mechanism and builds on the critical band concept introduced earlier in this chapter.