Higher-pitched voices resist reverberation and noise masking better than lower ones.

Evidence

Usually the only way of achieving this is to make use of the directivity of the loudspeakers used. This is because any other technique, such as reducing T60, tends to require major architectural changes and therefore considerable cost. However, sometimes this may be the only way of achiev­ ing a usable system. Sometimes communication can be assisted by using speakers with good elocution, especially female ones because their voices’ higher pitch tends to be less masked by the reverberation and noise typi­ cally present. Another possibility is to “chant” the message, which gives an exaggerated pitch contour that assists intelligibility. As a last resort one can use the international radiotelephony-spelling alphabet (Oscar, Bravo, Charlie …) to facilitate communication. Paradoxically electronic volume compression does not improve intelligibility; in many cases it makes it worse, because it can distort the syllabic amplitude variations that help us understand words. — David Howard, Jamie Angus, coustics and Psychoacoustics, 2481

Categorization

• XREF: Connects to the book’s masking and critical-band concepts — speech intelligibility depends on which frequency regions survive masking by reverberant noise.
• SEED: Angle: why public-address systems in stations and airports fail, and the counterintuitive acoustic fixes (directivity, chanting, spelling alphabets) that actually work.