The Effect of Single Harmonic Tuning on Vocal Loudness.

The study addresses the benefit of tuning single harmonics with vocal tract resonances to increase vocal loudness. The loudness of theoretically constructed vocal sounds with variable levels of sound energy in the first, second, and third harmonics is computed on the basis of ISO standard 226:2003. In comparison to increased loudness with changes in overall spectral slope, it is shown that single harmonic tuning requires a greater range of SPL to produce a similar range of loudness. For example, a 10-40 dB increase in the level of a single harmonic produces less than two doublings of loudness, whereas a spectral slope change from -12 dB/octave to -3 dB/octave can produce a similar doubling of loudness with only a 5 dB SPL increase.