Duration Of Fricative Noise Research Articles

아동이 산출한 치조마찰음 /ㅅ/에 대한 청지각적․음향학적 연구

This study examined the acoustic characteristics of Korean alveolar fricatives of normal children. Developing children aged 3 and 7, typically produced 2 types of nonsense syllables containing alveolar fricative /sV/ and /VsV/ sequences where V was any one of three corner vowels (/i, a, and u/). Stimuli containing the speech materials used in a production experiment were presented randomly to 12 speech language pathologists (SLPs) for a perception test. The SLPs responded by selecting one of seven alternative sounds. Acoustic measures such as duration of frication noise, normalized intensity, skewness, and center of gravity were examined. There was significant difference in acoustic measures when comparing vowels. Comparison of syllable structures indicated statistically significant differences in duration of frication noise and normalized intensity. Acoustic parameters could account for the perceptual data. Relating the acoustic and perception data by means of logistic regression suggests that duration of frication noise and normalized intensity are the primary cues to perceiving Korean fricatives.

Características acústicas dos fones [s] e [∫] de adultos e crianças com desenvolvimento fonológico típico

OBJETIVO: Comparar as produções de [s] e [∫] de adultos e crianças com desenvolvimento fonológico típico, considerando os parâmetros acústicos: duração do ruído fricativo, banda de frequências de concentração do ruído, frequência de corte de ruído de fricção e transição formântica da vogal seguinte. MÉTODOS: Participaram do estudo 26 sujeitos, divididos em dois grupos: Grupo de adultos (GA) - composto por 17 adultos jovens (média de idade: 23,61±3,44 anos), sem alterações em aspectos fonológicos da língua e; Grupo de crianças com desenvolvimento fonológico típico (GDFT) - composto por nove crianças (média de idade: 7,12±0,74 anos), com desenvolvimento fonológico típico. Foi realizada uma triagem fonoaudiológica e, após, coleta de dados para análise acústica e, para isso, foram utilizadas pseudopalavras inseridas em frases-veículo. Foram analisadas 624 produções dos sujeitos e os achados foram submetidos à análise estatística. RESULTADOS: Os parâmetros de banda de frequências e transição formântica apresentaram diferenças entre os grupos GA e GDFT. Na comparação entre as posições na palavra, os parâmetros de duração, frequência de corte e transição formântica apresentaram diferença. Os parâmetros de frequência de corte, banda de frequências e transição formântica apresentaram diferença na comparação entre os pontos de articulação de [s] e [∫]. CONCLUSÃO: Para a maioria dos parâmetros acústicos estudados, as produções de GA e GDFT mostraram-se semelhantes. Para alguns parâmetros, porém, puderam-se observar diferenças entre os grupos, entre as posições na palavra e entre os pontos de articulação dos fones estudados.

Altered acoustic cue discrimination in broca's and conduction aphasics

The present investigation explored the acoustic cue discrimination abilities of eight Broca's and four conduction aphasic patients and nine normal controls. A word-discrimination test was used to assess the subjects' ability to discriminate selected acoustic cues for distinctive features of phonemes. The words differed from one another by a selected minimal feature, such as stop-gap duration, duration of fricative noise, direction and extent of final format transition, or relative location of friction noise in the spectrum. Results indicated that performance for normal and aphasic subjects was poorer for altered temporal subtest items than for altered spectral subtest items. Within the spectral subtest, fewer Broca's aphasics than conduction aphasics passed the items, while 90% of the normals passed. Within the temporal subtest, fewer conduction aphasics than Broca's aphasics passed the items, while 75% of the normal subjects passed this subtest. The results support previous research suggesting that deficiencies in auditory processing of selected acoustic cues are not limited to Wernicke's aphasic individuals but may be found to a varying degree in several aphasic groups.

Duration of frication noise as a perceptual cue

Natural speech CV syllables ([f, s, š, ō, v, z, ð] in the environment of [i, u, a]) were computer edited to include 20–70 ms of frication noise as measured from its onset in 10‐ms steps, as well as the entire frication noise. These stimuli were presented to 12 subjects for consonant identification. Results showed high recognition scores (>75%) for all fricatives but [ō, ð] in the longer conditions (60 and 70 ms and the full frication noise). In the remaining conditions scores, although lower, were still significantly above chance. Perception of manner of articulation seemed to be minimally affected by a decrease in frication duration, with 86% correct scores in the 20‐ms condition. Perception of place of articulation was somewhat more affected by duration of the stimuli, with correct identification falling to 60% in the 20‐ms condition. Results suggest that while a minimum duration of about 20 ms is required for perception of manner of articulation, frication duration is not an important perceptual cue to either place or manner. Instead, spectral rather than temporal properties provide the major cues for place and manner of articulation for consonants.

On the complex regulating the voiced-voiceless distinction. I.

An investigation is described of the perceptual and acoustical differences between voiceless and voiced consonants in Dutch. The experiments reported included synthesized, normal and whispered speech. The results are compared with those found in the literature for other languages. Parallels between the results of the various investigations could be established, although quantitative differences apply to different languages. It is shown that a number of perceptual and acoustical cues are present, such as: sound intensity and duration of fricative noise, duration of the consonant and duration of the preceding vowel, voicing and the moment of voice onset, intonation pattern and amplitude as well as duration and frequency range of the formant transitions of the adjoining vowels. To establish a connection between these parameters an articulatory model of the difference voiced-voiceless is proposed. Essential features in the construction of this model are the observed acoustical symptoms and physiological data as reported in the literature. The model is based on the assumption that the difference voiced-voiceless is due to the presence or absence of activity of the pharyngeal constrictor muscle. This muscle influences the volume of the pharynx and the position of the larynx, and consequently the pressure drop across the glottis and the vibration condition of the vocal cords.