Speech sounds are typically perceived categorically. The acoustic information in speech sounds is perceptually grouped into phonetic categories. It is widely known that language influences the way speech sounds are categorized. That is, one's native language influences where category boundaries are placed. However, it is less understood how bilingual listeners categorize speech sounds. There is evidence showing that bilinguals have different category boundaries from monolinguals, but there is also evidence suggesting that bilinguals have different category boundaries depending on the language they are using at the moment. This phenomenon has been referred as the double phonetic boundary. The goal of this investigation was to verify the existence of the double phonemic boundary in bilingual listeners. As has been done in other studies, bilingual speakers of Spanish and English were asked to identify the speech sound /ta/ from a 10-token speech continuum ranging in VOT from /da/ to /ta/ in two language contexts. In this study, however, two additional procedures were carried out. First, English monolinguals were asked to identify the continuum in two language contexts. It was expected that bilinguals, but not monolinguals, would show a double phonetic boundary. Second, while participants' behavioral measures were assessed, electrophysiological measures [event-related potentials, (ERPs)] also were recorded. This was done in order to observe how speech sounds are represented in the brain. It as expected that bilinguals, but not monolinguals, would show different ERP amplitudes across language contexts. The behavioral results showed that phonemic boundaries did not differ across language contexts for either bilinguals or monolinguals. Further analyses showed bilinguals, but not monolinguals, perceived specific speech sounds--in the "ambiguous zone"--differently across language contexts. The electrophysiological results showed that the ERPs of bilinguals, but not monolinguals, differed across language contexts. Interestingly, behavioral measures correlated significantly with electrophysiological measures only in bilinguals. This result showed that the ERP amplitude was in accordance with the number of sounds perceived as 'ta' across language contexts. The challenges of testing the double phonemic boundary are discussed, along with the limitations of the methodology used in this study. / text

published_or_final_version / abstract / toc / Speech and Hearing Sciences / Master / Master of Science in Audiology

This study is limited standardization of the "Children's Speechreading Test" designed by Dr. Dolores S. Butt of the University of New Mexico. After studying the development of language skills in young acoustically handicapped children, she randomly selected subjects from 10 nursery schools and primary departments of schools for the deaf and administered her test to these children. The purpose of the present study is to provide a limited standardization of the "Children's speechreading Test" on normal hearing children. Although Dr. Butt indicates some relation of her test to intelligence, no attempt was made in this pilot study to correlate mental ability with speechreading ability. The "children's Speechreading Test" reproduced in complete form in Appendix A, was administered to 20 normal hearing children, all of whom were in the first grade. Information in the form of raw scores was then to utilized in calculating the standard deviation and percentile scores. Information gained from administering the test was also to be utilized to predict further investigation regarding the usefulness of this test. In addition a further purpose of this pilot project was to compile the materials necessary for administration of the test for future use in the Portland State University Speech and Hearing Clinic.

The investigator evaluated a commercially available Spanish word recognition ability test. The material consists of four lists of fifty bisyllabic tetraphonemic Spanish words available from Auditec of St. Louis as: "Spanish speech discrimination lists 1-4". Interlist equivalence, word difficulty, speaker's intelligibility, and P/I functions' slopes were investigated. Taped lists were presented to 16 normal hearing native Spanish speaking adults at four presentation levels. Statistical analysis indicated that the intelligibility of list three is significantly different than the other lists at the.05 level. At the low presentation levels, subjects of Mexican origin obtained better scores than subjects of other nationalities. The P/I functions' slope (4.3%) was comparable to that obtained by investigators of English tests. Most frequently missed words have as common denominators: presence of the /s/ sound, and are words that retain their meaning even after deletion of final /s/. Talker's speech intelligibility was judged to be very clear.

The purpose of this study was to investigate the effects of increased intensity on the bone conducted speech discrimination ability of normal listeners utilizing standard audiological equipment. The NU-6 word lists were utilized to test the bone conducted speech discrimination skills of ten normal hearing subjects, 21 to 30 years of age, on standard clinical equipment. Both the hearing levels (dB HL) and the sensation levels (dB SL) of the test administration were considered. In general, it was recommended that 100 dB Hl is the most appropriate dial setting for the administration of bone conducted speech discrimination tests even though comparable speech discrimination scores may be obtained with a 95 dB HL dial setting. This study indicates that the most appropriate sensation levels for the administration of bone conducted speech discrimination tests are 55 and 60 dB SL. Most normal listeners can be expected to achieve a 55 dB sensation level at the limits of the speech audiometer (100 dB HL). Additionally, it was found that when bone conducted speech discrimination tests are administered at levels of less than 55 dB SL, the results may be compromised by variances that occurred in this normal hearing sample. Therefore, the clinical audiologist should accept bone conducted speech discrimination results as valid only when the scores obtained at 40, 45 and 50 dB sensation levels are within the limits of clinical normality (90% or better). Recommendations for further research are discussed.

The purpose of this study was to investigate the effects of a 500 Hz and 3,150 Hz one-third octave band augmentation on the speech discrimination ability of listeners with cochlear hearing impairments. The results were analyzed both within the experimental group of subjects included in the present study and in comparison with data collected on a control group of normal hearing subjects reported earlier.

The limited amount of normative information regarding speech motor development in the clinically important age range four to seven years served as motivation for this study. The main aim of the study was to collect normative information regarding sensorimotor speech control skills of pre-school children. The method of the study was designed and the results interpreted within the framework of the four-level model of speech production of Van der Merwe (1997). Basic qualitative and quantitative data were gathered for a variety of aspects of speech motor development in Afrikaans-speaking children aged 4;0 to 6;7 years in the following areas: 1) non-speech oral movements, 2) non-speech diadochokinesis, 3) speech diadochokinesis, 4) cluster production, 5) word syllable structure in spontaneous speech, 6) acoustic data regarding first-vowel duration and variability of first-vowel duration in repeated utterances of the same word, 7) acoustic voice onset time data, 8) acoustic data regarding first-syllable duration in words of increasing length. Results indicated that associated movements and accuracy errors occurred in some non-speech oral movement and non-speech diadochokinesis tasks. Normative, diadochokinetic rate data were gathered. Perceptual analysis indicated difficulty with glottal and three-place diadochokinesis tasks. Subjects produced 84% of initial clusters in isolation correctly and 79% of final clusters. Schwa-vowel insertions occurred in clusters in isolation, but not in spontaneously produced words. Subjects produced 163 different word syllable structures in spontaneous speech, with 18 structures occurring in all subjects’ data. Six-year-olds generally displayed the shortest first-vowel duration. Individual, non-age related trends occurred for variability of first-vowel duration. Mean voice onset times in voiced stop contexts ranged from -97ms to +12ms, with overall instances of mean voicing lead occurring in 27% of the four-year olds’ productions, 4% of the five-year-olds’ productions and 80% of the six-year-olds’ productions. Mean voice onset times in voiceless stop contexts ranged from +11ms to +37ms. Subjects adapted first-syllable duration to word length by decreasing it as the word length increased. Results indicated that a wide range of normal speech motor performance is possible for children this age, and that individuals can display different performance levels for different speech parameters. This emphasizes the complexity of speech motor development and the need to assess a variety of speech motor parameters. It is essential that quantitative (objective) analysis of children’s speech motor performance be supplemented with qualitative (descriptive) analysis. The study contributed knowledge to the understanding of certain aspects of speech motor development and to the speech production process in general. / Dissertation (MComm Path)--University of Pretoria, 2007. / Speech-Language Pathology and Audiology / Unrestricted

A universal speech facilitation program was developed based on the principles, methods and long-term goals of an existing program, the Speech Motor Learning Program (Van der Merwe, 1985). The development of such a program was indicated because, to date, no systematized intervention program with the aim of general speech facilitation has been attempted to overcome the tremendous challenges of the current rehabilitative scenario in South Africa (shortage of services, untrained staff in the community and multiple language barriers to name a few). The suitability of the SMLP as a starting point for the compilation of a Speech Facilitation Program is illustrated by its clinical success in treating a variety of speech disorders and secondly because it is firmly based on normal speech development and motor learning principles. Based on the SMLP, the SFP was developed and applied to two paired subjects who exhibited general speech and language delay, to determine if the speech facilitation program would facilitate and indeed enhance speech development in the Subjects. The clinical application of the SFP was conducted in an alternating treatment design study using speech facilitation and language treatment respectively. During the treatment phase of the study, probe tests, consisting of ten selected aspects of speech and language, were conducted to determine the effect of the two treatment approaches on these aspects. Three of the aspects showed improvement following treatment with the Speech Facilitation Program. Four aspects showed gradual development throughout the duration of the study, irrespective of the type of treatment and it could possibly be attributed to general development by the subjects as well as regular intervention. Three aspects showed no change during the study. The obtained results seemed to indicate that the SFP influenced speech development positively and that it could be developed into a valuable clinical tool for the treatment of certain speech disorders. / Dissertation (MA (Communication Pathology))--University of Pretoria, 2007. / Speech-Language Pathology and Audiology / unrestricted

The purpose of this study was to develop two tape-recorded synthetic speech discrimination test tapes and assess their intelligibility in order to determine whether or not synthetic speech was intelligible and if it would prove useful in speech discrimination testing. Four scramblings of the second MU-6 monosyllable word list were generated by the ECHO l C speech synthesizer using two methods of generating synthetic speech called TEXTALKER and SPEAKEASY. These stimuli were presented in one ear to forty normal-hearing adult subjects, 36 females and 4 males, at 60 dB HL under headphone&. Each subject listened to two different scramblings of the 50 monosyllable word list, one scrambling generated by TEXTALKER and the other scrambling generated by SPEAKEASY. The order in which the TEXTALKER and SPEAKEASY mode of presentation occurred as well as which ear to test per subject was randomly determined.

The purpose of this study was to investigate the effects of a 500 Hz and 3150 Hz one-third octave band augmentation on the speech discrimination ability of normal hearing listeners and whether such effects vary with signal presentation level. The augmented portion of monosyllabic words was systematically varied from 5-55dB above the intensity level of the unfiltered version of the words and presented simultaneously to one ear.