Digital inverse filtering for linguistic research

To enable differences in modes of glottal vibration to be studied, glottal air volume velocity waveforms can be recovered from speech recordings by inverse filtering. Most previous published work in this area has made use of analog filters. Digital inverse filters offer many advantages, including the ability to change filter settings to match changing vocal tract filter functions. Although the theory and many of the methods necessary for digital inverse filtering have been described in the literature, a straightforward description of the entire process has been lacking. The digital inverse filtering process developed for linguistic research at the UCLA Phonetics Laboratory is described in detail in this paper, with the intention of facilitating such work at other institutions.