Page 247 - Master Handbook of Acoustics

FIGURE 12-4 An approximate relationship between absorption coefficients at normal incidence and
those with random incidence.

Individual reflections affect the timbre of sound. In particular, specific normal reflections, called
early sound, are of special interest. Although random-incidence coefficients are of interest in room
reverberation calculations, for image control problems, normal-incident reflection coefficients are
generally required.

Tone-Burst Method

Short pulses of sound can be used to perform anechoic acoustical measurements in ordinary rooms. It
takes time for reflections from walls and other surfaces to arrive at a measuring position. With a