Anders Löfqvist

The cricothyroid muscle in voicing control

Initiation and maintenance of vibrations of the vocal folds require suitable conditions of adduction, longitudinal tension, and transglottal airflow. Thus manipulation of adduction/abduction, stiffening/slackening, or degree of transglottal flow may, in principle, be used to determine the voicing status of a speech segment. This study explores the control of voicing and voicelessness in speech with particular reference to the role of changes in the longitudinal tension of the vocal folds, as indicated by cricothyroid (CT) muscle activity. Electromyographic recordings were made from the CT muscle in two speakers of American English and one speaker of Dutch. The linguistic material consisted of reiterant speech made up of CV syllables where the consonants were voiced and voiceless stops, fricatives, and affricates. Comparison of CT activity associated with the voiced and voiceless consonants indicated a higher level for the voiceless consonants than for their voiced cognates. Measurements of the fundamental frequency (F0) at the beginning of a vowel following the consonant show the common pattern of higher F0 after voiceless consonants. For one subject, there was no difference in cricothyroid activity for voiced and voiceless affricates; in this case, the consonant‐induced variations in the F0 of the following vowel were also less robust. Consideration of timing relationships between the EMG curves for voiced and voiceless consonants suggests that the differences most likely reflect control of vocal‐fold tension for maintenance or suppression of phonatory vibrations. The same mechanism also seems to contribute to the well‐known difference in F0 at the beginning of vowels following voiced and voiceless consonants.

Laryngeal vibrations: A comparison between high‐speed filming and glottographic techniques

This study was designed to compare information on laryngeal vibrations obtained by high-speed filming, photoglottography (PGG), and electroglottography (ECG). Simultaneous glottographic signals and high-speed films were obtained from two subjects producing steady phonation. Measurements of glottal width were made at three points along the glottis in the anterior--posterior dimension and aligned with the other records. Results indicate that PGG and film measurements give essentially the same information for peak glottal opening and glottal closure. The EGG signal appears to reliably indicate vocal-fold contact. Together, PGG and EGG may provide much of the information obtained from high-speed filming as well as potentially detect horizontal phase differences during opening and closing.

Speech as Audible Gestures

Speech can be described as audible movements. By varying the positions and trajectories of the lips, the jaw, the tongue, the velum, and the glottis, a speaker creates variations in air pressure and airflow in the vocal tract. These variations in pressure and flow produce the acoustic signal that we hear when listening to speech. For this acoustic signal to be not only audible, but also structured in such a way that it can transmit linguistic information, the articulators have to be controlled and coordinated so that the acoustic variations in the produced signal conform to the phonetics and phonology of the language being spoken. This paper examines several aspects of the control and coordination of articulatory gestures during speech, with particular emphasis on gestural patterning, gestural coherence, and gestural aggregation

Initial validation of an indirect measure of subglottal pressure during vowels

Some methods for direct measurement of subglottal pressure during speech are invasive and thus cannot be used on a routine basis. The development of noninvasive techniques is thus desirable, and a simple indirect method for measuring subglottal pressure from records of oral pressure during consonants has recently been proposed and applied to studies of glottal resistance during phonation. In order to bae useful, indirect measurement procedures should be validated by comparisons with direct measurements, and the present experiment was designed for such a comparison. Miniature pressure transducers were used to obtain records of pressure below and above the glottis. Results showed nonsignificant differences and a high correlation between the direct and indirect measurements. This indirect method for measuring subglottal pressure thus appears to provide valid results.

Working memory and novel word learning in children with hearing impairment and children with specific language impairment

BACKGROUND Working memory is considered to influence a range of linguistic skills, i.e. vocabulary acquisition, sentence comprehension and reading. Several studies have pointed to limitations of working memory in children with specific language impairment. Few studies, however, have explored the role of working memory for language deficits in children with hearing impairment. AIMS The first aim was to compare children with mild-to-moderate bilateral sensorineural hearing impairment, children with a preschool diagnosis of specific language impairment and children with normal language development, aged 9-12 years, for language and working memory. The special focus was on the role of working memory in learning new words for primary school age children. METHODS & PROCEDURES The assessment of working memory included tests of phonological short-term memory and complex working memory. Novel word learning was assessed according to the methods of. In addition, a range of language tests was used to assess language comprehension, output phonology and reading. OUTCOMES & RESULTS Children with hearing impairment performed significantly better than children with a preschool diagnosis of specific language impairment on tasks assessing novel word learning, complex working memory, sentence comprehension and reading accuracy. No significant correlation was found between phonological short-term memory and novel word learning in any group. The best predictor of novel word learning in children with specific language impairment and in children with hearing impairment was complex working memory. Furthermore, there was a close relationship between complex working memory and language in children with a preschool diagnosis of specific language impairment but not in children with hearing impairment. CONCLUSIONS Complex working memory seems to play a significant role in vocabulary acquisition in primary school age children. The interpretation is that the results support theories suggesting a weakened influence of phonological short-term memory on novel word learning in school age children.

Is age at implant the only factor that counts? The influence of working memory on lexical and grammatical development in children with cochlear implants

In this study, we explored the influence of time factors (age at implant, time with cochlear implant and age), complex working memory and phonological short-term memory on lexical and grammatical development in congenitally deaf children with cochlear implants. Fifteen children (aged 5 years 4 months to 11 years 5 months) were examined with the use of several linguistic and cognitive measures after a minimum of 18 months of implant use. Phonological short-term memory was assessed with non-word repetition, where the percentage of correctly repeated consonants and vowels was counted. For the assessment of lexical acquisition, a novel word learning task was administered. Receptive and expressive grammar was tested. Our results corroborate earlier findings on the influence of phonological short-term memory on novel word learning. The percentage of vowels correctly produced in non-word repetition was more important in this group than age at implant, not only for novel word learning, but also for receptive and expressive grammar. Sumario En este estudio, exploramos la influencia sobre el desarrollo léxico y gramatical de los factores temporales (edad de implantación, edad y tiempo transcurrido con el implante), de la memoria activa compleja y de la memoria fonológica a corto plazo, en niños con sorderas congénitas y portadores de un implante coclear. Se examinaron quince niños (con edades de 5 años y 4 meses a 11 años y 5 meses) por medio de varias medidas cognitivas y lingüísticas, luego de un mínimo de 18 meses de uso del implante. La memoria fonológica a corto plazo fue evaluada por medio de la repetición de sonidos sin contenido semántico, donde se tabuló el porcentaje de vocales y consonantes correctamente repetidas. Para la evaluación de la adquisición del léxico, se administró una novedosa tarea de aprendizaje de palabras y se evaluó la gramática receptiva y expresiva. Nuestros resultados corroboraron hallazgos anteriores sobre la influencia de la memoria fonológica a corto plazo en el aprendizaje de nuevas palabras. El porcentaje de vocales correctamente producidas por medio de la repetición de sonidos sin contenido semántico fue más importante en este grupo que la edad de implantación, no sólo para el aprendizaje de palabras nuevas, sino también en cuanto a la gramática receptiva y expresiva.

Accurate recovery of articulator positions from acoustics: New conclusions based on human data

Vocal tract models are often used to study the problem of mapping from the acoustic transfer function to the vocal tract area function (inverse mapping). Unfortunately, results based on vocal tract models are strongly affected by the assumptions underlying the models. In this study, the mapping from acoustics (digitized speech samples) to articulation (measurements of the positions of receiver coils placed on the tongue, jaw, and lips) is examined using human data from a single speaker: Simultaneous acoustic and articulator measurements made for vowel-to-vowel transitions, /g/ closures, and transitions into and out of /g/ closures. Articulator positions were measured using an EMMA system to track coils placed on the lips, jaw, and tongue. Using these data, look-up tables were created that allow articulator positions to be estimated from acoustic signals. On a data set not used for making look-up tables, correlations between estimated and actual coil positions of around 94% and root-mean-squared errors around 2 mm are common for coils on the tongue. An error source evaluation shows that estimating articulator positions from quantized acoustics gives root-mean-squared errors that are typically less than 1 mm greater than the errors that would be obtained from quantizing the articulator positions themselves. This study agrees with and extends previous studies of human data by showing that for the data studied, speech acoustics can be used to accurately recover articulator positions.

Speaker's Comfort in Teaching Environments: Voice Problems in Swedish Teaching Staff.

OBJECTIVES The primary objective of this study was to examine how a group of Swedish teachers rate aspects of their working environment that can be presumed to have an impact on vocal behavior and voice problems. The secondary objective was to explore the prevalence of voice problems in Swedish teachers. METHOD Questionnaires were distributed to the teachers of 23 randomized schools. Teaching staff at all levels were included, except preschool teachers and teachers at specialized, vocational high schools. The response rate was 73%. RESULTS The results showed that 13% of the whole group reported voice problems occurring sometimes, often, or always. The teachers reporting voice problems were compared with those without problems. There were significant differences among the groups for several items. The teachers with voice problems rated items on room acoustics and work environment as more noticeable. This group also reported voice symptoms, such as hoarseness, throat clearing, and voice change, to a significantly higher degree, even though teachers in both groups reported some voice symptoms. Absence from work because of voice problems was also significantly more common in the group with voice problems--35% versus 9% in the group without problems. CONCLUSION We may conclude that teachers suffering from voice problems react stronger to loading factors in the teaching environment, report more frequent symptoms of voice discomfort, and are more often absent from work because of voice problems than their voice-healthy colleagues.

Interarticulator programming in VCV sequences: Lip and tongue movements

This study examined the temporal phasing of tongue and lip movements in vowel-consonant-vowel sequences where the consonant is a bilabial stop consonant /p, b/ and the vowels one of /i, a, u/; only asymmetrical vowel contexts were included in the analysis. Four subjects participated. Articulatory movements were recorded using a magnetometer system. The onset of the tongue movement from the first to the second vowel almost always occurred before the oral closure. Most of the tongue movement trajectory from the first to the second vowel took place during the oral closure for the stop. For all subjects, the onset of the tongue movement occurred earlier with respect to the onset of the lip closing movement as the tongue movement trajectory increased. The influence of consonant voicing and vowel context on interarticulator timing and tongue movement kinematics varied across subjects. Overall, the results are compatible with the hypothesis that there is a temporal window before the oral closure for the stop during which the tongue movement can start. A very early onset of the tongue movement relative to the stop closure together with an extensive movement before the closure would most likely produce an extra vowel sound before the closure.

Laryngeal adjustments in the production of consonant clusters and geminates in American English

The glottal opening gesture and its timing control in various sequences of voiceless obstruents were investigated by the combined techniques of electromyography, photo‐electric glottography, and fiberoptic endoscopy. The results obtained at both electromyographic and movement levels revealed that the glottal opening gesture is characterized by a one‐, two‐, or more‐than‐two‐peaked pattern in a regular fashion according to the phonetic nature of the voiceless segments: each voiceless obstruent or geminate accompanied by aspiration or frication noise tends to require a single separate peak of the opening gesture, while an unaspirated stop embedded in a voiceless environment can be produced within the opening gesture attributed to an adjacent aspirated stop or fricative. Such an independent opening gesture of the glottis for the production of voiceless aspirated stops or voiceless fricatives even in sequentially unvoiced contexts can be interpreted as assuring the aerodynamic requirements for turbulent noise production during the aspirated stop or fricative segment.