Static measurements of vowel formant frequencies and bandwidths: A review

Abstract

The lifespan database on vowel formants shows considerable variability within specific age-sex groups, pointing to the need for standardized procedures.

Comparison of fundamental frequency and formants frequency measurements in two speech tasks

“…Therefore, by establishing an acoustic-articulatory correspondence, it is possible to infer that the tongue was in a lower position and the mandible in more open position, besides having occurred greater narrowing of the pharynx in the carrier phrases in relation to the sustained vowels 7 . A hypothesis for the differentiation found between the two speech tasks would be the interference of the coarticulation phenomenon present in continuous speech, once a given segment influences adjacent segments; i.e., in the analyzed vowel, there are acoustic hints of the consonant that precedes it 7,12,26 . In women, the differences found only in the vowels (Figures 3 and 4).…”

“…Based on the observation of these data, it is possible to infer, by means of an acoustic-articulatory correspondence, that the tongue constriction position was more posterior and the conformation of the pharynx was narrower 7 than in the sustained vowels. A hypothesis for the reduction in F2 values would be a greater interference of the coarticulation present in the continuous speech in these vowels, since the movement of the articulators to produce a sound will change because of the nearby sounds 7,12,26 . The lower F2 values in the CP in all posterior vowels in both genders may have been favored by the tongue posterior constriction inherent to their production.…”

Detrending the Waveforms of Steady-State Vowels

“…While our contention that such uncertainty quantification is desirable stems mainly from a principled point of view [ 9 ], we argue that in critical cases such as forensic speaker identification [ 10 ], the ability to assign a degree of confidence to formant measurements—upon which further conclusions rest—is valuable, perhaps essential, and well worth the considerable extra computational effort required (As far as we know, while “there is a huge and increasing demand for [forensic speaker identification] expertise in courts” [ 10 ] (p. 255), uncertainty quantification for formant measurements is currently not in (widespread) use in forensics [ 10 , 11 , 12 ]. We are aware of several works on quantifying and discussing the nature of the variability and reliability of formant measurements that have been published quite recently [ 2 , 13 , 14 , 15 , 16 , 17 ]; this matter is discussed further in the conference paper under the umbrella term “the formant measuring problem”). In more routine circumstances one may simply take the error bars on the formant estimates as a practical measure of the computer program’s trust in its own output.…”

“…Two features of Pinson’s model are of interest here. The first one is that the bandwidth estimates obtained by this method seem to be (much) more reliable than those obtained by today’s standard linear predictive coding (LPC) methods [ 13 , 14 ], when compared to bandwidths measured by independent methods [ 4 , 34 , 35 ]. The second one is the direct parametrization of the model function in Equation ( 2 ) by the formant bandwidths and frequencies , which, as we explain in Section 3 , transparently enables uncertainty quantification for their estimates in a straightforward and transparent way—this is much harder in LPC-like methods.…”

A New Approach to the Formant Measuring Problem

“…For example, formants are considered to be primary features for distinguishing vowel classes, speech perception and for inferring speaker identity, sex and age. Despite this fundamental status-and despite a long history of work on vowel formants starting out with [2]-the issue of making accurate measurements of the formant parameters, which we dub "the formant measurement problem" for convenience, is as yet not considered to be fully resolved (e.g., [3][4][5]). Accordingly, a large amount of formant measurement methods exist in the literature, of which most rely on linear predictive (LPC) analysis.…”