Learning to pronounce vowel sounds in a foreign language using acoustic measurements of the vocal tract as feedback in real time

An acoustic impedance spectrometer was used to measure the frequencies R1 and R2 of the first two resonances of the vocal tract. The measurement was made just outside the mouth, in parallel with the free field, using a new technique that provides precise information about the acoustic response of the vocal tract in real time. Values measured for native speakers for a particular vowel were used as target parameters for subjects who used a visual display of an impedance spectrum of their own vocal tracts as real-time feedback to realise the vocal tract configuration required to pronounce the target vowel. We report the values (R1,R2) for eleven non-nasalised vowels of French. These values are similar to the formant frequencies measured previously for these vowels, and their relative positions in the (R2,R1) plane are similar to those of the same vowels in the (F2,F1) formant plane. The confusion and correct identification of these vowels are shown to be strongly related to their separation in the (R2,R1) plane. We report the results of attempts to imitate six of these vowels by monolingual anglophone subjects. One group used a traditional method of learning pronunciation: they heard the vowel sounds and then attempted to imitate them. Another group also heard the sounds, but were assisted by the vocal tract feedback described above when imitating the target sounds. The acoustic properties and recognizability of the vowels were significantly superior when the subjects used vocal-tract feedback.