The study involves tests on the perception by speakers of Finnish of vowel sounds in natural speech in four important varieties of standard Swedish and as produced by an OVE III synthesizer.The contrastive analysis takes the form of experiments to reveal the divisions of the vowel space in Swedish and Finnish. Perceptually optimal areas and the diffuse zones in the vowel space are contrasted. On the basis of these tests predictions are made concerning second language perceptual problems.The contrastive relations of the vowel sounds in Swedish and Finnish are further illuminated by perceptual tests to study the inherent tendency of speakers of Finnish to confuse certain Swedish vowels. The distribution of the phonemic reactions of speakers of Finnish not knowing Swedish are taken as material for an error analysis relevant to the time of starting to learn Swedish. A number of phonemically long vowel sounds were discovered to cause problems of identification for Finnish listeners. These are / y:/, /in:/, /e:/, / e :/, /#:/, and /o:/. A comparison of the predictions and actual confusions shows a high degree of correlation.Finnish vowel harmony was found to be a factor influencing the responses of Finns to Swedish vowels. The responses to combinations of vowels not complying with the vowel harmony rules contained an increased proportion of confusions leading to harmony-compatible or neutral vowels. Also the vowel qualities which were in an intermediate position in the vowel space in relation to the Finnish vowels tended to be influenced by assimilation or sequential contrast.The perceptual interference properties of the mother tongue in the perception of the vowel qualities as illuminated by the results of the perceptual test are discussed.Certain didactic conclusions are drawn concerning the problems experienced by speakers of Finnish in the identification and also the production of the Swedish vowels. Gestures of lip position and its contrastive perceptual effects are noted to be of especial importance in the learning of the vowel qualities of Swedish by Finns. / digitalisering@umu

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The purpose of this study was to compare changes in acoustic and kinematic measures of articulation across soft, comfortable, and loud speech conditions. There were 19 participants, 9 male and 10 female, with age ranging from 20 to 34 with a median age of 25. Each participant had electromagnetic sensors glued to their tongue, jaw, and lips. It was anticipated that the acoustic measures would accurately reflect the kinematic measures of speech as articulation changed across the intensity levels. Vowel space area (VSA) and vowel articulation index (VAI) were computed from the three corner vowels, /α, i, u/. Articulatory-acoustic vowel space (AAVS), a sentence-level acoustic measure, was computed from the continuous formant histories for all voiced segments in a sentence. Kinematic-vowel space area (KVSA), kinematic-vowel articulation index (KVAI), and articulatory-kinematic vowel space (AKVS) were the kinematic equivalents of the acoustic measures, and were newly developed for the present study. Stroke metrics based on the speed history of the lingual movements were also used to reveal average kinematic features of the articulatory gestures in each participant's speech. The data revealed that the isolated acoustic and kinematic measures that used corner vowels (VSA, VAI. KVSA, KVAI) did not change significantly with intensity. The sentence-level continuous measures of articulatory working space (AAVS and AKVS) increased as speech intensity increased. The other sentence-level kinematic metrics also changed significantly with speech intensity, including increases in hull volume, onset speed, peak speed, mean speed, and distance. Stroke duration decreased as speech intensity increased. These findings suggest that measures based on isolated corner vowels are not as reflective as continuous measures of changes in articulatory movement in speech.

Aim The aim of this study was to determine how deterioration of voice quality, such as breathiness, may impact on the intelligibility of speech. Method Acoustic analysis was conducted on sustained vowel phonation (/i/ and /a/) and sentences produced by voice disordered speakers. Measures included: frequency and amplitude of the first two formants (F1, F2), singing power ratio (SPR), the amplitude difference between the first two harmonics (H1-H2), voice onset time (VOT), and energy ratio between consonant and vowel (CV energy ratio). A series of two-way (glottal closure by vowel) mixed design between and within-subjects Analysis of Variances conducted on these acoustic measures showed a significant glottal closure (complete and incomplete) or glottal closure by vowel interaction effect on the F2 frequency, H1-H2 amplitude difference, and singing power ratio. Based on findings in literature that reported a dominant first harmonic as a useful predictor of breathiness, the measure of H1-H2 amplitude difference was selected as a factor for investigation of the impact of voice quality on the perception of vowel intelligibility and clarity. Fixed-length vowel segments at five levels of H1-H2 amplitude difference were presented to 10 male and 10 female inexperienced listeners between the ages of 19 and 34 years. Results It was expected that the tokens with a dominant first harmonic, indicative of a more breathy voice, would be associated with a lower rate of correct vowel identification and of being perceived as “clearer”. Although no linear relationship between breathiness and intelligibility was revealed, results indicated the presence of thresholds of intelligibility for particular vowels whereby once a level of breathiness was reached intelligibility would decline. Conclusion The finding of a change of the perceptual ratings as a function of the H1-H2 amplitude difference, identified in previous studies as a measure of breathiness, revealed thresholds of intelligibility for particular vowels below which breathiness would be tolerated with little impact on intelligibility but beyond which intelligibility ratings suffered markedly.

The change a speaker makes in response to background noise is known as the Lombard Effect (LE). This study investigated the acoustic changes that are undergone in the presence of broadband noise and two-talker babble. Of particular interest were vocal fundamental frequency (F0) and formant frequency vowel space measures across sex. Forty participants (20 male, 20 female) were recruited and asked to read phrases in quiet and in the presence of two-talker babble and broadband noise. These masker conditions were presented at 50 and 70 dB HL. The phrases were recorded and acoustically analysed. The results showed a significant sex difference for both F0 and vowel space. A masking condition effect was not displayed for either F0 or vowel space. A significant effect was however shown for F0 according to intensity level, suggesting a LE. While the sex difference in F0 values can be explained on the basis of differences in vocal anatomy, the sex difference in vowel space was indicative of a sociophonetic influence on speech production.

abstract: The activation of the primary motor cortex (M1) is common in speech perception tasks that involve difficult listening conditions. Although the challenge of recognizing and discriminating non-native speech sounds appears to be an instantiation of listening under difficult circumstances, it is still unknown if M1 recruitment is facilitatory of second language speech perception. The purpose of this study was to investigate the role of M1 associated with speech motor centers in processing acoustic inputs in the native (L1) and second language (L2), using repetitive Transcranial Magnetic Stimulation (rTMS) to selectively alter neural activity in M1. Thirty-six healthy English/Spanish bilingual subjects participated in the experiment. The performance on a listening word-to-picture matching task was measured before and after real- and sham-rTMS to the orbicularis oris (lip muscle) associated M1. Vowel Space Area (VSA) obtained from recordings of participants reading a passage in L2 before and after real-rTMS, was calculated to determine its utility as an rTMS aftereffect measure. There was high variability in the aftereffect of the rTMS protocol to the lip muscle among the participants. Approximately 50% of participants showed an inhibitory effect of rTMS, evidenced by smaller motor evoked potentials (MEPs) area, whereas the other 50% had a facilitatory effect, with larger MEPs. This suggests that rTMS has a complex influence on M1 excitability, and relying on grand-average results can obscure important individual differences in rTMS physiological and functional outcomes. Evidence of motor support to word recognition in the L2 was found. Participants showing an inhibitory aftereffect of rTMS on M1 produced slower and less accurate responses in the L2 task, whereas those showing a facilitatory aftereffect of rTMS on M1 produced more accurate responses in L2. In contrast, no effect of rTMS was found on the L1, where accuracy and speed were very similar after sham- and real-rTMS. The L2 VSA measure was indicative of the aftereffect of rTMS to M1 associated with speech production, supporting its utility as an rTMS aftereffect measure. This result revealed an interesting and novel relation between cerebral motor cortex activation and speech measures. / Dissertation/Thesis / Doctoral Dissertation Speech and Hearing Science 2018

The discovery of 5,500 Homo heidelbergensis fossil specimens at the Sima de los Huesos archaeological site in Spain has opened up the opportunity for research to be conducted on the vocal capabilities of this species. Previous research has revealed that the range of vowel sounds an individual can produce, known as the vowel space, is directly affected by the dimensions of the vocal tract. The vowel spaces of two hominins, Homo sapiens and Homo neanderthalensis, have been reconstructed through previous research. However, the vowel space of Homo heidelbergensis has not yet been reconstructed. In this research, I aim to explore how the dimensions of the Homo heidelbergensis vocal tract affect the vowel space of that species. This was pursued by measuring the craniospinal dimensions of five Homo heidelbergensis specimens through three dimensional imaging software. When measurements were unattainable due to limitations in the fossil record, regression equations were used to predict missing measurements. By doing so, the vowel space of this species was reconstructed, and crucial information into the vocal capabilities of this close human ancestor was revealed.

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Research on clear speech has shown that the type of clear speech produced can vary depending on the speaker, the listener and the medium. Although prior research has suggested that clear speech is more intelligible than conversational speech for normal-hearing listeners in noisy environments, it is not known which acoustic features of clear speech are the most responsible for enhanced intelligibility and comprehension. This thesis focused on investigating the acoustic characteristics that are produced in clear speech to foreigners and infants. Its aim was to assess the utility of these features in enhancing speech intelligibility and comprehension. The results of Experiment 1 showed that native speakers produced exaggerated vowel space in natural interactions with foreign-accented listeners compared to native-accented listeners. Results of Experiment 2 indicated that native speakers exaggerated vowel space and pitch to infants compared to clear read speech. Experiments 3 and 4 focused on speech perception and used transcription and clarity rating tasks. Experiment 3 contained speech directed at foreigners and showed that speech to foreign-accented speakers was rated clearer than speech to native-accented speakers. Experiment 4 contained speech directed at infants and showed that native speakers rated infant-directed speech as clearer than clear read speech. In the fifth and final experiment, naturally elicited clear speech towards foreign-accented interlocutors was used in speech comprehension tasks for native and non-native listeners with varying proficiency of English. It was revealed that speech with expanded vowel space improved listeners’ comprehension of speech in quiet and noise conditions. Results are discussed in terms of the Lindblom’s (1990) theory of Hyper and Hypoarticulation, an influential framework of speech production and perception.

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) has received more attention in recent years as a treatment option for regulating the symptoms of Parkinson's disease. Previous studies of DBS documented consistent improvements in motor function but more variability in speech outcomes. In the present study, six participants diagnosed with idiopathic Parkinson's disease who reported worsened speech with stimulation were recorded performing speech acoustic tasks with the stimulators on, and again with the stimulators off. Improvements were noted for most participants in measurements of formant slopes, long term average spectrum (LTAS) of a sustained vowel, and spirantization with stimulation on. Stimulation negatively affected most participants' vowel space area, verbal fluency, sequential motion rate, and LTAS while reading and describing a picture. Measures of stop gap duration, alternating motion rate, and voice onset time were within normal limits for most participants across both stimulation conditions.