Which phonetic features should pronunciation Instructions focus on? An evaluation on the accentedness of segmental/syllable errors in L2 speech

Many English language instructors are reluctant to incorporate pronunciation instruction into their teaching curriculum (Thomson 2014). One reason for such reluctance is that L2 pronunciation errors are numerous, and there is not enough time for teachers to address all of them (Munro and Derwing 2006; Thomson 2014). The current study aims to help language teachers set priorities for their instruction by identifying the segmental and structural aspects of pronunciation that are most foreign-accented to native speakers of American English. The current study employed a perception experiment. 100 speech samples selected from the Speech Accent Archive (Weinberger 2016) were presented to 110 native American English listeners who listened to and rated the foreign accentedness of each sample on a 9-point rating scale. 20 of these samples portray no segmental or syllable structure L2 errors. The other 80 samples contain a single consonant, vowel, or syllable structure L2 error. The backgrounds of the speakers of these samples came from 52 different native languages. Global prosody of each sample was controlled for by comparing its F0 contour and duration to a native English sample using the Dynamic Time Warping method (Giorgino 2009). The results show that 1) L2 consonant errors in general are judged to be more accented than vowel or syllable structure errors; 2) phonological environment affects accent perception, 3) occurrences of non-English consonants always lead to higher accentedness ratings; 4) among L2 syllable errors, vowel epenthesis is judged to be as accented as consonant substitutions, while deletion is judged to be less accented or not accented at all. The current study, therefore, recommends that language instructors attend to consonant errors in L2 speech while taking into consideration their respective phonological environments

Plasticity in speech perception – effects of learning, age and bilingualism

Brain plasticity enables us to learn to perceive languages. Theories and models of non-native language learning predict learning difficulties in phonological areas where the native and non-native phonological systems overlap and where a category boundary of one language may lie somewhere within a category of another language. Phonologically, these areas are interesting within the two native languages of bilinguals from birth also. In this thesis, both psychophysiological and behavioural measurements were used to explore the neural plasticity in relation to learning, age, and bilingualism. The research questions were, whether phonological processing is different between different kinds of bilinguals and whether it is different between bilinguals from birth and monolinguals. A further research question was, whether different background factors, such as manner and age of learning, affect memory trace formation. The bilinguals from birth, simultaneous bilinguals, seem to have a shared phonological system for the two languages, whereas later bilinguals, sequential bilinguals, seem to have separate phonological systems for the languages. The shared system in the simultaneous bilinguals leads to slower processing compared to sequential bilinguals and monolinguals. The languages seem to be active all the time in the shared phonological system irrespective of the language context. Whereas the sequential bilinguals, with the separate systems, can even ignore their native language in a second language context. The studies on the manner and age of learning revealed that both classroom and laboratory training lead to similar functioning of memory traces. The laboratory training effects also seem to be permanent. However, the age of learning affects memory trace formation: While the young adults show memory trace formation during laboratory training, the elderly do not show the same effect. In conclusion, different types of bilinguals process speech differently and simultaneous bilinguals’ speech processing is different from that of monolinguals’. Training in classroom and in laboratory lead to similar functioning of memory traces. Age, however, affects plasticity and laboratory training does not lead to similar training effects in the elderly compared to young adults.Plastisiteetti puheen havaitsemisessa – Oppiminen, ikä ja kaksikielisyys Kielen omaksuminen tai oppiminen on mahdollista muovautuvien aivojemme vuoksi. Vieraan kielen oppimisteoriat ennustavat oppimisvaikeuksia sellaisilla fonologisilla alueilla, joilla äidinkielen ja vieraan kielen äännejärjestelmät ovat limittäiset eli alueilla, joilla toisen kielen äännekategorian raja sijoittuu toisen kielen äännekategorian sisään. Tällaiset fonologiset seikat ovat mielenkiintoisia myös syntymästään asti kaksikielisten kohdalla. Tämän tutkimuksen tarkoituksena oli tutkia neuraalista muovautuvuutta vieraan kielen havaitsemisessa oppimisen, iän ja kaksikielisyyden suhteen käyttäen sekä psykofysiologisia että behavioraalisia menetelmiä. Tutkimusten oli toisaalta tarkoitus selvittää, eroaako puheen neuraalinen prosessointi samanaikaisilla ja peräkkäisillä kaksikielisillä sekä eroaako puheen havaitseminen samanaikaisilla kaksikielisillä ja yksikielisillä. Toisaalta selvitettiin, muokkaantuuko yksikielisten puheen prosessointi samankaltaiseksi kuin peräkkäisillä kaksikielisillä kuuntele ja toista harjoittelun myötä ja ovatko harjoittelun vaikutukset pysyviä. Lisäksi selvitettiin eri taustatekijöiden –oppimistavan ja -iän – vaikutuksia muistijälkien syntyyn. Tutkimusten mukaan samanaikaisilla kaksikielisillä näyttää olevan yksi yhtenäinen fonologinen järjestelmä, kun taas peräkkäisillä kaksikielisillä näyttää olevan kaksi erillistä järjestelmää. Yhtenäisessä järjestelmässä molemmat kielet ovat koko ajan aktiivisia kielikontekstista riippumatta, mikä hidastaa prosessointia suhteessa erilliseen järjestelmään. Peräkkäiset kaksikieliset taas voivat toisen kielensä kontekstissa jättää äidinkielensä täysin huomiotta. Oppimistapaan ja -ikään liittyvät tutkimukset osoittivat luokkahuone- ja laboratorioharjoittelun johtavan samanlaiseen muistijälkien toimimiseen. Laboratorioharjoittelun vaikutukset näyttivät myös olevan pysyviä. Oppimisikä vaikuttaa kuitenkin muistijälkien syntyyn eri tavoin: nuorille aikuisille syntyy muistijäljet laboratorioharjoittelun vaikutuksesta, mutta vastaavaa ei nähdä iäkkäämmillä, jo eläkkeellä olevilla henkilöillä. Näyttää siis siltä, että eri tyyppiset kaksikieliset prosessoivat puhetta eri tavoin ja että samanaikaisten kaksikielisten puheen havaitsemisen prosessointi eroaa yksikielisistä. Kuuntele ja toista harjoittelulla voidaan saavuttaa puheen neuraalisen prosessoinnin taso, joka on samankaltainen kuin peräkkäisillä kaksikielisillä. Ikä kuitenkin vaikuttaa muovautuvuuteen eikä sama harjoittelu toimi iäkkäämmillä henkilöillä samalla tavalla kuin nuorilla aikuisilla

The impact of head and body postures on the acoustic speech signal

This dissertation is aimed at investigating the impact of postural changes within speakers on the acoustic speech signal to complement research on articulatory changes under the same conditions. The research is therefore relevant for forensic phonetics, where quantifying within-speaker variation is vital for the accuracy of speaker comparison. To this end, two acoustic studies were carried out to quantify the influence of five head positions and three body orientations on the acoustic speech signal. Results show that there is a consistent change in the third formant, a change which was most evident in the body orientation measurements, and to a lesser extent in the head position data. Analysis of the results with respect to compensation strategies indicates that speakers employ different strategies to compensate for these perturbations to their vocal tract. Some speakers did not exhibit large differences in their speech signal, while others appeared to compensate much less. Across all speakers, the effect was much stronger in what were deemed ‘less natural’, postures. That is, speakers were apparently less able to predict and compensate for the impact of prone body orientation on their speech than for that of the more natural supine orientation. In addition to the acoustic studies, a perception experiment assessed whether listeners could make use of acoustic cues to determine the posture of the speaker. Stimuli were chosen with, by design, stronger or weaker acoustic cues to posture, in order to elicit a possible difference in identification performance. Listeners were nevertheless not able to identify above chance whether a speaker was sitting or lying in prone body orientation even when hearing the set with stronger cues. Further combined articulatory and acoustic research will have to be carried out to disentangle which articulatory behaviours correlate with the acoustic changes presented in order to draw a more comprehensive picture of the effects of postural variation on speech.This work was supported by the Art and Humanities Research Council