Throughout this work, the time-harmonic factor exp (iωt) is assumed and suppressed.
Fig. 15 Harmonic richness factor (HRF) shift versus normalized amplitude quotient (NAQ) shift for each speaker across the entire corpus.
That study measured six parameters, the harmonic richness factor (HRF), normalized amplitude quotient (NAQ), H1 H2 ratio (H1H2), F1F3syn [25], harmonics-to-noise ratio (HNR), and spectral slope (SS).
There are also parameters not required in the standard but required in the grid codes, e.g. the THFF (telephone harmonic form factor).
These two are correlated, with a correlation value of r = −0.53 Fig. 14 Harmonic richness factor (HRF) versus fundamental Frequency (F0) for each speaker across the entire corpus.
While there was less separation across speech types for the H1 H2 ratio, the harmonic richness factor was lower for soft speech.
Fig. 7 The normalized amplitude quotient (NAQ) across entire corpus Fig. 8 The harmonic richness factor (HRF) across entire corpus Fig. 9 The normalized amplitude quotient (NAQ) for the single female speaker (FJF3) Fig. 10 The harmonic richness factor (HRF) for the single female speaker (FJF3).
The harmonic richness factor (HRF) is the ratio of the sum of the amplitudes at the harmonics in the glottal waveform to the amplitude of the component at the fundamental frequency [36].
Drugman et al. [40] showed that NAQ, H1H2 ratio, and harmonic richness factor (HRF) measured for soft, modal, and loud speech resulted in significantly different distributions in these parameters for a corpus of a single speaker.
Harmonic richness factor (HRF) and normalized amplitude quotient (NAQ) have been selected because past studies have quantified the relationship of these parameters to specific speaking behaviors including pressed speech and soft speech.
Three signal processing-based values which include (i) the normalized amplitude quotient (NAQ), (ii) the harmonic richness factor (HRF), and (iii) the fundamental frequency are used to measure voice quality.
