11/12/2023 0 Comments Lpc praat formant extraction![]() ![]() However, it has also long been recognized that measuring formant frequencies is not straightforward. As vocal tract imaging has advanced, the first test of a new method often involves a comparison of vowel formants: those measured from a speaker's acoustic output, those predicted from that speaker's vocal tract shape as measured with a new technique, and those predicted using previous techniques (e.g., Baer et al., 1991 Davies et al., 1992 Story et al., 1996). The acoustic theory of speech production shows that the shape of the vocal tract determines the acoustic output we then perceive as speech ( Fant, 1960). These have been used for many purposes: for example, to characterize the differences in vowel space of men, women, and children (e.g., Peterson and Barney, 1952) and of the hearing-impaired ( Monsen, 1976) to compare dialects (e.g., Clopper and Pierrehumbert, 2008) to compare speaking styles ( Bradlow, 2002) and to provide basic data with which formant synthesizers can be specified ( Allen et al., 1987). Vowel production has often been characterized by measurements of the formants, especially the formant frequencies ( Chiba and Kajiyama, 1941). In addition, RS coped better with weaker formants and glottal fry. Results for the natural speech show that F0 bias affects all automatic methods, including WLP-AME only the formants measured manually from RS appeared to be accurate. In the second experiment, these methods were used on vowels in isolated words spoken by four speakers. All but WLP-AME and RS had large errors in the direction of the strongest harmonic the smallest errors occur with WLP-AME and RS. Formants were also measured manually from pruned reassigned spectrograms (RSs). Input formant values were compared to manual measurements and automatic measures using the linear prediction coding-Burg algorithm, linear prediction closed-phase covariance, the weighted linear prediction-attenuated main excitation (WLP-AME) algorithm, spectra smoothed cepstrally and by averaging repeated discrete Fourier transforms. ![]() In the first, synthetic vowels were constructed with five different first formant ( F1) values and nine different F0 values formant bandwidths, and higher formant frequencies, were constant. Approaches to reducing the errors were assessed in two experiments. The measurement of formant frequencies of vowels is among the most common measurements in speech studies, but measurements are known to be biased by the particular fundamental frequency ( F0) exciting the formants. ![]()
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