Nutrition education tools used in phenylketonuria: clinician, parent and patient perspectives from three international surveys.

BACKGROUND: Three international surveys were developed aiming to identify the current nutrition educational tools used in the management of phenylketonuria (PKU) and the perceived effectiveness of these tools by clinicians, parents and patients. METHODS: The first two surveys were distributed through the Metabolic Dietitians ListServe (pno-metabl@listserv.cc.emory.edu), and the third survey was distributed by international clinics and the National PKU Alliance website (www.npkua.org). A total of 888 responses (S1, n = 88; S2, n = 81; S3, n = 719) were collected from all three surveys. The surveys represent participants from 17 countries, in Europe; North America (USA and Canada); Mexico; Argentina; Turkey; Australia; and Africa (Tunisia). RESULTS: A consistent decline in 'parents as role models' as an educational tool was observed starting at age 10 years. Patients responded they feel their families are the most effective form of education, whereas handouts were selected as the least effective educational tool by patients. Parents responded they feel the most effective educational tool is one-on-one counselling. Patients and parents show a desirable trend in wanting to attend group clinic, even in centres where this type of educational tool is not offered. CONCLUSIONS: There was a discrepancy between clinicians and patient views regarding the perceived effectiveness of the nutrition education tools. Future research is needed surrounding the impact nutrition education may have on improved dietary compliance in patients with PKU.

Four-year follow-up study of language impaired children.

Children identified as normal or as specifically language impaired (SLI) were given speech, language, and intelligence testing on a longitudinal basis. Fourteen normal and 29 SLI children between the ages of 4 1/2 and 8 years were tested at Time 1. They were retested three to four years later when they were 8 to 12 years old. The results indicated that both the normal and the SLI children continued to develop skills in receptive and expressive language and speech articulation across the 3- to 4-year period intervening between evaluations. Overall, however, the SLI children appeared to develop language skills at a slower than normal rate and 80% of them remained language impaired at Time 2. In addition, the majority of the SLI children manifested reading impairment at Time 2, while none of the normal children did so. The implications for the educational management of SLI children are discussed.

Speech training aids for hearing-impaired individuals: I. Overview and aims.

Prelingual profound deafness typically results in aberrant or unintelligible speech production. For approximately 70 years, researchers and engineers have attempted, with little success, to provide electronic aids for speech training. Recent computer and signal processing technology has provided the impetus for several groups to implement new speech training aids. Following a review of deaf speech characteristics, several current computer-based aids are described. Included among those reviewed are two interrelated speech training aids which resulted from collaboration among the authors.

Speech training aids for hearing-impaired individuals: II. Configuration of the Johns Hopkins aids.

Two interrelated personal computer (PC) based speech training aids have been developed: one for use in a school or clinic, the Speech Training Station (STS); and the other for the deaf child's home, the Speech Practice Station (SPS). The STS monitors speech production by microphone, electroglottograph, and pneumotachograph. The SPS system uses only the microphone input. Both systems utilize commercially available board-level hardware and a custom analog preprocessor board for the analysis of the acoustic and/or physiologic inputs. The school system has been used by speech therapists for diagnosis, training by game playing, and specification of exercises for the SPS. The home system provides directed speech practice between therapy sessions.

Speech training aids for hearing-impaired individuals: III. Preliminary observations in the clinic and childrens' homes.

Preliminary evaluation of 2 related computer-based speech training and practice aids for profoundly deaf children was conducted. The Speech Training Station (STS) uses both acoustic and physiological transducters for assessment and training in a school of clinic. The Speech Practice Station (SPS) uses the acoustic signal, and was designed primarily for use in the home. A series of games and activities was implemented on the 2 systems. Use of the STS was evaluated by 2 speech clinicians during a 15-month period. Fifteen children were subjects in the evaluation. The aid was found to be easily incorporated into clinic activities and useful for diagnosis and therapy. The SPS was evaluated during a 1-to-2-week period, during which it was placed in the homes of 5 profoundly deaf children. Using an activity log and questionnaire completed by the childrens' parents, usage statistics and impressions were obtained. Potential value and problems with such aids are discussed.

Relationships between subjective ratings and objective measures of performance in speechreading sentences.

Ninety-six participants with normal hearing and 63 with severe-to-profound hearing impairment viewed 100 CID Sentences (Davis & Silverman, 1970) and 100 B-E Sentences (Bernstein & Eberhardt, 1986b). Objective measures included words correct, phonemes correct, and visual-phonetic distance between the stimulus and response. Subjective ratings were made on a 7-point confidence scale. Magnitude of validity coefficients ranged from .34 to .76 across materials, measures, and groups. Participants with hearing impairment had higher levels of objective performance, higher subjective ratings, and higher validity coefficients, although there were large individual differences. Regression analyses revealed that subjective ratings are predictable from stimulus length, response length, and objective performance. The ability of speechreaders to make valid performance evaluations was interpreted in terms of contemporary word recognition models.

Enhanced speechreading in deaf adults: can short-term training/practice close the gap for hearing adults?

This study investigated effects of short-term training/practice on group and individual differences in deaf and hearing speechreaders. In two experiments, participants speechread sentences with feedback during training and without feedback during testing, alternating 10 times over six sessions spanning up to 5 weeks. Testing used sentence sets balanced for expected mean performance. In each experiment, participants were adults who reported good speechreading and either normal hearing (n = 8) or severe to profound hearing impairments (n = 8). The experiments were replicates, except that in one participants received vibrotactile speech stimuli in addition to visible speech during training, testing whether vibrotactile speech enhances speechreading learning. Results showed that (a) training/practice did not alter the relative performance among individuals or groups; (b) significant learning occurred when training and testing were conducted with speechreading only (although the magnitude of the effect was small); and (c) there was evidence that the vibrotactile training depressed rather than raised speechreading scores over the training period.

Sources of variability in speechreading sentences: a generalizability analysis.

Generalizability theory (Cronbach, Gleser, Nanda, & Rajaratnam, 1972) was used to estimate the percentage of variance explained by three sources of variability in speechreading sentences: the subject, the talker, and the sentence materials. Videodisc recordings of the 100 CID Everyday Sentences (Davis & Silverman, 1970), spoken by a male and a female talker, were presented to 104 subjects with normal hearing. For performance on individual sentences (total number of words correct), the most important systematic sources of variability were the sentence (26.3%), the speechreader (10.5%), the talker (4.9%), and the interaction of talker and sentence (5.1%). Residual error accounted for 51.2% of the variance. Generalizability functions are presented, as a function of test length, for five models of test administration and interpretation. For 10-, 50-, and 100-item lists, generalizability is predicted to be .70, .92, and .96, respectively, for a single talker. Psychometric characteristics of these recordings of the CID sentences are also presented.

Speechreading and the structure of the lexicon: computationally modeling the effects of reduced phonetic distinctiveness on lexical uniqueness.

A lexical modeling methodology was employed to examine how the distribution of phonemic patterns in the lexicon constrains lexical equivalence under conditions of reduced phonetic distinctiveness experienced by speech-readers. The technique involved (1) selection of a phonemically transcribed machine-readable lexical database, (2) definition of transcription rules based on measures of phonetic similarity, (3) application of the transcription rules to a lexical database and formation of lexical equivalence classes, and (4) computation of three metrics to examine the transcribed lexicon. The metric percent words unique demonstrated that the distribution of words in the language substantially preserves lexical uniqueness across a wide range in the number of potentially available phonemic distinctions. Expected class size demonstrated that if at least 12 phonemic equivalence classes were available, any given word would be highly similar to only a few other words. Percent information extracted (PIE) [D. Carter, Comput. Speech Lang. 2, 1-11 (1987)] provided evidence that high-frequency words tend not to reside in the same lexical equivalence classes as other high-frequency words. The steepness of the functions obtained for each metric shows that small increments in the number of visually perceptible phonemic distinctions can result in substantial changes in lexical uniqueness.

Speech perception development in language-impaired children: a 4-year follow-up study.

A group of specifically language-impaired (SLI) children was compared with a matched group of non-SLI children (i.e., children displaying normal language) on tests of speech perception and language ability. The tests were administered longitudinally at times separated by an interval of 4 years. Initially (i.e., Time 1), the groups differed significantly in discrimination, sequencing, and rate processing of and serial memory for synthesized /ba/ and /da/ stimuli. At Time 1, age effects were also observed among both groups of children. That is, performance improved as a function of increased age. At follow-up (i.e., Time 2), performance was at or near ceiling for subjects in both groups, indicating that perceptual development occurred in both groups of children. Results are discussed in relation to the hypothesis that perceptual deficits play a causal role in specific language impairment.

Vocal communication in the first 18 months of life.

Fifty-one normally developing infants aged birth to 18 months, 10 or 11 in each of five age groups, were videorecorded in their homes before and after an expected change in the form of their vocalizations and under a set of conditions that reflected common daily occurrences. The vocalizations produced were coded according to their communicative contexts, defined in nonvocal behavioral terms. Communicative codes were assigned to seven major categories. The distribution of codes across categories was found to be different for different age groups. It varied between the first and second observations; however, the pattern of change differed across age groups. Data from individuals were transformed to proportions, to control for individual differences in productivity. They were then found to reflect differences in level of development of vocal communication. It was concluded that vocal communication follows an orderly developmental sequence in normally developing infants in the first 18 months of life.

Child and adult vibrotactile thresholds for sinusoidal and pulsatile stimuli.

Three experiments were performed to obtain vibrotactile sensitivity thresholds from hearing children and adults, and from deaf children. An adaptive two-interval forced-choice procedure was used to obtain estimates of the 70.7% point on the psychometric sensitivity curve. When hearing children of 5-6 and 9-10 years of age and adults were tested with sinusoids and haversine pulse stimuli, at 10, 100, 160, and 250 Hz or pps, respectively, only the 10-Hz stimulus resulted in an age effect. For this stimulus, young children were significantly less sensitive than adults. When sinusoids were again tested at 20, 40, 80, and 160 Hz, a small overall effect of age was observed with a significant effect only at 20 Hz. Two prelingually profoundly deaf children were tested with haversine pulse trains at 10, 50, 100, 160, and 250 pps. Both children were at least as sensitive to the tactile stimulation as were the hearing children and adults. Pulsatile stimulation, compared to sinusoidal stimulation, exhibited relatively flat threshold versus frequency functions. The present results, demonstrating no age effect for pulsatile stimulation and similar performance for deaf and hearing children, suggest that pulsatile stimulation would be appropriate in vibrotactile speech communication aids for the deaf.

Temporal and spatio-temporal vibrotactile displays for voice fundamental frequency: an initial evaluation of a new vibrotactile speech perception aid with normal-hearing and hearing-impaired individuals.

Four experiments were performed to evaluate a new wearable vibrotactile speech perception aid that extracts fundamental frequency (F0) and displays the extracted F0 as a single-channel temporal or an eight-channel spatio-temporal stimulus. Specifically, we investigated the perception of intonation (i.e., question versus statement) and emphatic stress (i.e., stress on the first, second, or third word) under Visual-Alone (VA), Visual-Tactile (VT), and Tactile-Alone (TA) conditions and compared performance using the temporal and spatio-temporal vibrotactile display. Subjects were adults with normal hearing in experiments I-III and adults with severe to profound hearing impairments in experiment IV. Both versions of the vibrotactile speech perception aid successfully conveyed intonation. Vibrotactile stress information was successfully conveyed, but vibrotactile stress information did not enhance performance in VT conditions beyond performance in VA conditions. In experiment III, which involved only intonation identification, a reliable advantage for the spatio-temporal display was obtained. Differences between subject groups were obtained for intonation identification, with more accurate VT performance by those with normal hearing. Possible effects of long-term hearing status are discussed.

Potential perceptual bases for successful use of a vibrotactile speech perception aid.

This paper examines the possibility that perception of vibrotactile speech stimuli is enhanced in adults with early and life-long use of hearing aids. We present evidence that vibrotactile aid benefit in adults is directly related to the age at which the hearing aid was fitted and the duration of its use. The stimulus mechanism responsible for this effect is hypothesized to be long-term vibrotactile stimulation by high powered hearing aids. We speculate on possible mechanisms for enhanced vibrotactile speech perception as the result of hearing aid use: (1) long-term experience receiving degraded or improverished speech stimuli results in a speech processing system that is more effective for novel stimuli, independent of perceptual modality; and/or (2) long-term sensory/perceptual experience causes neural changes that result in more effective delivery of speech information via somatosensory pathways.

A computational approach to analyzing sentential speech perception: phoneme-to-phoneme stimulus-response alignment.

A solution to the following problem is presented: Obtain a principled approach to studying error patterns in sentence-length responses obtained from subjects who were instructed to simply report what a talker had said. The solution is a sequence comparator that performs phoneme-to-phoneme alignment on transcribed stimulus and response sentences. Data for developing and testing the sequence comparator were obtained from 139 normal-hearing subjects who lipread (speechread) 100 sentences and from 15 different subjects who identified nonsense syllables by lipreading. Development of the sequence comparator involved testing two different costs metrics (visemes versus Euclidean distances) and two related comparison algorithms. After alignments with face validity were achieved, a validation experiment was conducted for which measures from random versus true stimulus-response sentence pairs were compared. Measures of phonemes correct and substitution uncertainty were found to be sensitive to the nature of the sentence pairs. In particular, correct phoneme matches were extremely rare in random pairings in comparison with true pairs. Also, an information-theoretic measure of uncertainty for substitutions in true versus random pairings showed that uncertainty was always higher for random than for true pairs.

Generalizability of speechreading performance on nonsense syllables, words, and sentences: subjects with normal hearing.

Ninety-six adults with normal hearing viewed three types of recorded speechreading materials (consonant-vowel nonsense syllables, isolated words, and sentences) on 2 days. Responses to nonsense syllables were scored for syllables correct and syllable groups correct; responses to words and sentences were scored in terms of words correct, phonemes correct, and an estimate of visual distance between the stimulus and the response. Generalizability analysis was used to quantify sources of variability in performance. Subjects and test items were important sources of variability for all three types of materials; effects of talker and day of testing varied but were comparatively small. For each type of material, alternative models of test construction and test-score interpretation were evaluated through estimation of generalizability coefficients as a function of test length. Performance on nonsense syllables correlated about .50 with both word and sentence measures, whereas correlations between words and sentences typically exceeded .80.

Amplitude and period discrimination of haptic stimuli.

As part of a project to examine the ability of the hand to receive speech information, the present study examined subjects' ability to discriminate finger movements along the dimensions of amplitude and period (movement duration). The movements consisted of single-cycle, sinewave movements and single-cycle, cosine movements presented to the index finger. Difference thresholds were collected using an adaptive, two-interval, temporal forced-choice procedure. Amplitudes from 6 to 19 mm were examined, and the difference thresholds ranged from 10% to 18%. The thresholds were unaffected by the period of the movement. Periods from 3000 to 111 ms (0.33-9 Hz) were examined, and thresholds ranged from 6% to 16%. The thresholds were unaffected by the amplitude of the movement. Further measurements in which period was varied in the amplitude discrimination task and amplitude was varied in the period discrimination task indicated that subjects were not using peak velocity as the basis for discrimination. These measurements were collected using a display specifically designed for the examination of haptic stimulation and capable of presenting controlled patterns of movement and vibration to the fingers.

Single-channel vibrotactile supplements to visual perception of intonation and stress.

Two experiments were conducted to explore the effectiveness of a single vibrotactile stimulator to convey intonation (question versus statement) and contrastive stress (on one of the first three words of four 4- or 5-word sentences). In experiment I, artificially deafened normal-hearing subjects judged stress and intonation in counterbalanced visual-alone and visual-tactile conditions. Six voice fundamental frequency-to-tactile transformations were tested. Two sentence types were voiced throughout, and two contained unvoiced consonants. Benefits to speechreading were significant, but small. No differences among transformations were observed. In experiment II, only the tactile stimuli were presented. Significant differences emerged among the transformations, with larger differences for intonation than for stress judgments. Surprisingly, tactile-alone intonation identification was more accurate than visual-tactile for several transformations.

Is subjective word familiarity a meter of ambient language? A natural experiment on effects of perceptual experience.

The present study examined the sensitivity of a subjective familiarity measure to differences in word exposure within and between populations that differ dramatically in their perceptual experience. Descriptive measures of language ability and subjective familiarity ratings for 450 words were collected from a group of college-educated adults with normal hearing and a group of college-educated deaf adults. The results demonstrate the sensitivity of subjective familiarity ratings to both between- and within-group differences in word experience. Specifically, the deaf participants consistently rated words as less familiar than did hearing participants. Furthermore, item-level correlations within a participant group were higher than ones between groups. Within groups, mean familiarity ratings were correlated with descriptive measures of language ability. The results are discussed in relation to a simple sampling model of word experience and the language experience of the participant groups.