Detection of Phone Boundaries for Non-Native Speech using French-German Models

International audienceWithin the framework of computer assisted foreign language learning for the French/German pair, we evaluate different HMM phone models for detecting accurate phone boundaries. The optimal parameters are determined by minimizing on the non-native speech corpus the number of phones whose boundaries are shifted by more than 20 ms compared to the manual boundaries. We observe that the best performance was obtained by combining a French native HMM model with an automatically selected German native HMM model

Analysis of phone confusion matrices in a manually annotated French-German learner corpus

International audienceThis paper presents an analysis of the non-native and native pronunciations observed in a phonetically annotated bilingual French-German corpus. After a forced-choice automatic annotation a large part of the corpus was checked and corrected manually on the phone level which allows a detailed comparison of the realized sounds with the expected sounds. The analysis is reported in terms of phone confusion matrices for selected error-prone classes of sounds. It revealed that German learners of French have most problems with obstruents in word-final position whereas French learners of German show complex interferences with the vowel contrasts for length and quality. Finally, the correct pronunciation rate of the sounds, for several phonetic classes, is analyzed with respect to the learner's level, and compared to native pronunciations. One outcome is that different sound classes show different correct rates over the proficiency levels. For the German data the frequently occurring syllabic [=n] is a prime indicator of the proficiency level

L1-L2 Interference: The case of final devoicing of French voiced fricatives in final position by German learners

International audienceThis work is dealing with a case of L1-L2 interference in language learning. The Germans learning French as a second language frequently produce unvoiced fricatives in word-final position instead of the expected voiced fricatives. We investigated the production of French fricatives for 16 non-native (8 beginner-and 8 advanced-learners) and 8 native speakers, and designed auditory feedback to help them realize the right voicing feature. The productions of all speakers were categorized either as voiced or unvoiced by experts. The same fricatives were also evaluated by non-experts in a perception experiment targeting VCs. We compare the ratings by experts and non-experts with the feature-based analysis. The ratio of locally unvoiced frames in the consonantal segment and also the ratio between consonantal duration and V1 duration were measured. The acoustic cues of neighboring sounds and pitch-based features play a significant role in the voicing judgment. As expected, we found that beginners face more difficulties to produce voiced fricatives than advanced learners. Also, the production becomes easier for the learners, especially for the beginners, if they practice repetition after a native speaker. We use these findings to design and develop feedback via speech analysis/synthesis technique TD-PSOLA using the learner's own voice

Methods of investigating vowel interferences of French learners of German

International audienceThe French and German vowel inventories [Fougeron & Fougeron, 1999, Kohler, 1999] show many similarities, for instance, both have a series of front rounded vowels. Contrary to German, French has no vowel length contrast. Although specialized teaching materials for German consider the problem of vowel length/tenseness (e.g. [Hirschfeld, 2014; Hirschfeld et al., 2007]), it is still unclear how frequently vowel errors occur in L2 speech and which pairs of long-tense and short-lax vowels create the most serious difficulties for French learners of German. We present three methods to analyze the interference processes occurring in read speech of French learners of German (60 sentences, 50 subjects). First, we analyzed phone confusion matrices based on hand-labeled data. The most frequent confusions appear for two long-tense/short-lax distinctions. Second, in a perception study, German native speakers listened to words belonging to minimal pairs like Miete - Mitte ('rent-middle') differing in length/tenseness. Results indicate that, overall, short vowels were identified correctly less often (64\%) than long vowels (77\%), but with great inter-individual differences. Although most problems occur in the beginner group, every second advanced learner shows for short vowels an identification rate lower than chance, which means they were perceived as long by German native listeners.Finally, acoustic measurements of the minimal pair words revealed very different strategies: some speakers show a general tendency to lengthen and other speakers to shorten vowels.The results of these three investigations help to create a more detailed account of the transfer of vowel contrasts, extending prior research on vowel perception [Kingston, 2003; Flege & MacKay, 2004], with orthography as a possible source of interference. Furthermore, the results of the studies can be used to create individualized training and feedback for foreign language learners

Methods of investigating vowel interferences of French learners of German

International audienceThe French and German vowel inventories [Fougeron & Fougeron, 1999, Kohler, 1999] show many similarities, for instance, both have a series of front rounded vowels. Contrary to German, French has no vowel length contrast. Although specialized teaching materials for German consider the problem of vowel length/tenseness (e.g. [Hirschfeld, 2014; Hirschfeld et al., 2007]), it is still unclear how frequently vowel errors occur in L2 speech and which pairs of long-tense and short-lax vowels create the most serious difficulties for French learners of German. We present three methods to analyze the interference processes occurring in read speech of French learners of German (60 sentences, 50 subjects). First, we analyzed phone confusion matrices based on hand-labeled data. The most frequent confusions appear for two long-tense/short-lax distinctions. Second, in a perception study, German native speakers listened to words belonging to minimal pairs like Miete - Mitte ('rent-middle') differing in length/tenseness. Results indicate that, overall, short vowels were identified correctly less often (64\%) than long vowels (77\%), but with great inter-individual differences. Although most problems occur in the beginner group, every second advanced learner shows for short vowels an identification rate lower than chance, which means they were perceived as long by German native listeners.Finally, acoustic measurements of the minimal pair words revealed very different strategies: some speakers show a general tendency to lengthen and other speakers to shorten vowels.The results of these three investigations help to create a more detailed account of the transfer of vowel contrasts, extending prior research on vowel perception [Kingston, 2003; Flege & MacKay, 2004], with orthography as a possible source of interference. Furthermore, the results of the studies can be used to create individualized training and feedback for foreign language learners

The Perceptual Effect of L1 Prosody Transplantation on L2 Speech: The Case of French Accented German

Research has shown that language learners are not only challenged by segmental differences between their native language (L1) and the second language (L2). They also have problems with the correct production of suprasegmental structures, like phone/syllable duration and the realization of pitch. These difficulties often lead to a perceptible foreign accent. This study investigates the influence of prosody transplantation on foreign accent ratings. Syllable duration and pitch contour were transferred from utterances of a male and female German native speaker to utterances of ten French native speakers speaking German. Acoustic measurements show that French learners spoke with a significantly lower speaking rate. As expected, results of a perception experiment judging the accentedness of 1) German native utterances, 2) unmanipulated and 3) manipulated utterances of French learners of German suggest that the transplantation of the prosodic features syllable duration and pitch leads to a decrease in accentedness rating. These findings confirm results found in similar studies investigating prosody transplantation with different L1 and L2 and provide a beneficial technique for (computer-assisted) pronunciation training

Acoustic correlates of L2 prosodic boundaries by German learners of French

International audienceDeviations in L2 intonation affect a number of prosodic characteristics including pitch range, declination line, or the rises of non-final IPs, and might lead to misunderstandings or contribute to the perception of foreign-accent. This study investigates the characteristics of non-native speech at the boundary between prosodic constituents. We analyzed a French declarative sentence, extracted from the IFCASL corpus (www.ifcasl.org), made up of four constituents and pronounced with a neutral intonation. Each constituent has three syllables and the sentence is realized typically by French speakers with four accentual –prosodic- groups, corresponding to the four constituents. Fourty German learners of French (beginners, and advanced speakers) and fifty four French speakers read the sentence once. We used the software ProsodyPro from Yi Xu for the prosodic analysis. We determined the presence of pauses and evaluated for each prosodic group: the (normalized) F0 maximum on the last syllable; the F0 excursion (max-min) of the final contour, and its maximum of velocity. In order to analyze the temporal course of F0 on the final contour, we also compared the values of the F0 excursion on the vowel and before it. On the basis of acoustic cues, non-native speakers, especially beginners, appear to realize more important prosodic boundaries (in particular higher F0 maxima, especially at the very end of the prosodic group, and more pauses) than French speakers, whereas native speakers appear to show more anticipation

The IFCASL corpus as a phonetic learner corpus

Phonetic learner corpora represent a special type of spoken learner corpora by providing detailed phonetic and phonological annotation in the form of phonetic transcription as well as the segmentation and labelling of the speech signal on the levels of segments, syllables, words and sentences. This time-consuming post-processing enables a better acoustic analysis of the data and provides many options for using audio data in teaching foreign languages. It also offers good opportunities to develop tools for computer-aided pronunciation training. The possibilities and restrictions of phonetic learner corpora are illustrated with the bidirectional German–French IFCASL corpus

Optimization-based modeling of Lombard speech articulation:Supraglottal characteristics

This paper shows that a highly simplified model of speech production based on the optimization of articulatory effort versus intelligibility can account for some observed articulatory consequences of signal-to-noise ratio. Simulations of static vowels in the presence of various background noise levels show that the model predicts articulatory and acoustic modifications of the type observed in Lombard speech. These features were obtained only when the constraint applied to articulatory effort decreases as the level of background noise increases. These results support the hypothesis that Lombard speech is listener oriented and speakers adapt their articulation in noisy environments.</p

Comparing Annotations of Non-verbal Vocalisations in Speech Corpora

In this study eleven corpora of spontaneous and scripted speech (in English and in German) are analysed regarding their annotation inventories of selected highly frequent nonverbal vocalisations (NVVs). It appears that only one corpus considers all NVVs and that laughter is the only NVV annotated in all corpora. The findings lead to a discussion of possible reasons for this situation. In conclusion it is argued that a wider distribution and more consistency is needed with respect to the annotation of NVVs