On H1-H2 as an acoustic measure of linguistic phonation type.

The measure H1-H2, the difference in amplitude between the first and second harmonics, is frequently used to distinguish phonation types and to characterize differences across voices and genders. While H1-H2 can differentiate voices and is used by listeners to perceive changes in voice quality, its relation to voice articulation is less straightforward. Its calculation also involves practical issues with error propagation. This paper highlights some developments in the use of H1-H2 and proposes a new measure that we call "residual H1." In residual H1, the amplitude of the first harmonic is normalized against the overall sound energy (as measured by root mean square energy) instead of against H2. Residual H1 may mitigate some of the issues with using H1-H2. The current study tests the correlation between residual H1 and electroglottographic contact quotient (CQ) and compares the ability of residual H1 vs H1-H2 to differentiate statistically across phonation types in !Xóõ and utterance-level changes in phonatory quality in Mandarin. The results show that residual H1 has a stronger correlation with CQ and differentiates contrastive and allophonic phonatory quality better than H1-H2, particularly for more constricted phonation types.