A differentially amplified motion in the ear for near-threshold sound detection

The ear is a remarkably sensitive pressure fluctuation detector. In guinea pigs, behavioral measurements indicate a minimum detectable sound pressure of ~20 μPa at 16 kHz. Such faint sounds produce 0.1-nm basilar membrane displacements, a distance smaller than conformational transitions in ion channels. It seems that noise within the auditory system would swamp such tiny motions, making weak sounds imperceptible. Here we propose a new mechanism contributing to a resolution of this problem and validate it through direct measurement. We hypothesized that vibration at the apical side of hair cells is enhanced compared with that at the commonly measured basilar membrane side. Using in vivo optical coherence tomography, we demonstrated that apical-side vibrations peaked at a higher frequency, had different timing and were enhanced compared with those at the basilar membrane. These effects depend nonlinearly on the stimulus sound pressure level. The timing difference and enhancement of vibrations are important for explaining how the noise problem is circumvented.

from Nature Neuroscience

Position-dependent patterning of spontaneous action potentials in immature cochlear inner hair cells

Spontaneous action potential activity is crucial for mammalian sensory system development. In the auditory system, patterned firing activity has been observed in immature spiral ganglion and brain-stem neurons and is likely to depend on cochlear inner hair cell (IHC) action potentials. It remains uncertain whether spiking activity is intrinsic to developing IHCs and whether it shows patterning. We found that action potentials were intrinsically generated by immature IHCs of altricial rodents and that apical IHCs showed bursting activity as opposed to more sustained firing in basal cells. We show that the efferent neurotransmitter acetylcholine fine-tunes the IHC’s resting membrane potential (Vm), and as such is crucial for the bursting pattern in apical cells. Endogenous extracellular ATP also contributes to the Vm of apical and basal IHCs by triggering small-conductance Ca2+-activated K+ (SK2) channels. We propose that the difference in firing pattern along the cochlea instructs the tonotopic differentiation of IHCs and auditory pathway.

from Nature Neuroscience

Auditory aversive learning increases discrimination thresholds

Animal studies of discriminative fear conditioning traditionally use stimuli that are distant in physical features and thus easily distinguished perceptually. Independently, human studies have shown that training mostly improves discrimination thresholds. We found that aversive learning actually induced an increase in discrimination thresholds in humans and that subjective aversion during conditioning predicted the individual threshold change. This counterintuitive performance deterioration occurred when using odors or sounds as aversive reinforcers and was not a result of attentional distraction or decision bias. In contrast, positive reinforcement or mere exposure induced the typically reported decrease in thresholds. Our findings indicate that aversive outcomes induce wider stimulus generalization by modulating perceptual thresholds, suggesting the engagement of low-level mechanisms. We suggest that for risk- or loss-related stimuli, less specificity could be a benefit, as it invokes the same mechanisms that respond quickly and efficiently in the face of danger.

from Nature Neuroscience

Transitions in neural oscillations reflect prediction errors generated in audiovisual speech

According to the predictive coding theory, top-down predictions are conveyed by backward connections and prediction errors are propagated forward across the cortical hierarchy. Using MEG in humans, we show that violating multisensory predictions causes a fundamental and qualitative change in both the frequency and spatial distribution of cortical activity. When visual speech input correctly predicted auditory speech signals, a slow delta regime (3–4 Hz) developed in higher-order speech areas. In contrast, when auditory signals invalidated predictions inferred from vision, a low-beta (14–15 Hz) / high-gamma (60–80 Hz) coupling regime appeared locally in a multisensory area (area STS). This frequency shift in oscillatory responses scaled with the degree of audio-visual congruence and was accompanied by increased gamma activity in lower sensory regions. These findings are consistent with the notion that bottom-up prediction errors are communicated in predominantly high (gamma) frequency ranges, whereas top-down predictions are mediated by slower (beta) frequencies.

from Nature Neuroscience

Oral reading rates of second-grade students.

The importance of reading fluently is widely recognized in school effectiveness, reform, and improvement efforts of the educational community, yet there are few large-scale, structured assessments of the progression of students’ reading rates over time. This study documented 2nd-grade students’ oral reading rates on the basis of fall, winter, and spring assessments. Using growth curve analysis, we identified models for a sample (n = 5,796) of students in 79 schools in a large urban school district in the United States. We found that, although school characteristics were significant predictors of the children’s initial oral reading status, they were mostly not significant predictors of their reading rate over time. At the individual level, girls had a better performance than did boys in reading achievement testing, and no statistically significant difference was noted between boys and girls in their growth rates during the 2nd grade. On the other hand, special education children not only achieved less than did non-special education children in oral reading but also evidenced a significantly lower rate of increase. The trustworthiness of “at risk” and “low risk” instructional recommendations on the basis of oral reading rates was high. We discuss these findings in light of the existing research on reading fluency. Our findings have implications for research and instruction for fluency and literacy development of both fluent and nonfluent readers. (PsycINFO Database Record (c) 2011 APA, all rights reserved)

from the Journal of Educational Psychology

Cognitive–linguistic foundations of early spelling development in bilinguals.

Developing spelling skills in English is a particularly demanding task for Chinese speakers because, unlike many other bilinguals learning English as a second language, they must learn two languages with different orthography as well as phonology. To disentangle socioeconomic and pedagogical factors from the underlying cognitive–linguistic processes that predict the development of spelling, we used a 6-month longitudinal design and compared children with English as their first language (English-L1; n = 50) and children with Mandarin as their first language (Mandarin-L1; n = 50) from the same kindergarten. Both groups were tested on parallel versions of English and Mandarin tasks as predictors at Time 1, and their spelling sophistication scores were then computed from a 52-item experimental task administered at Time 2. After we controlled for nonverbal IQ, age, vocabulary, and spelling achievement on Wide Range Achievement Test 4 at Time 1, regression analyses showed that phoneme awareness was the strongest predictor of spelling sophistication for English-L1 children, but syllable awareness and letter-sound knowledge were also important for Mandarin-L1 children. The implications of these differences in the cognitive–linguistic processing of bilingual children learning two dissimilar languages are briefly discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)

from the Journal of Educational Psychology

Consequence of Preterm Birth in Early Adolescence: The Role of Language on Auditory Short-term Memory

This study tested the hypothesis that preterm early adolescents’ short-term memory is compromised when presented with increasingly complex verbal information and that associated neuroanatomical volumes would differ between preterm and term groups. Forty-nine preterm and 20 term subjects were evaluated at age 12 years with neuropsychological measures and magnetic resonance imaging (MRI). There were no differences between groups in simple short-term and working memory. Preterm subjects performed lower on learning and short-term memory tests that included increased verbal complexity. They had reduced right parietal, left temporal, and right temporal white matter volumes and greater bilateral frontal gray and right frontal white matter volumes. There was a positive association between complex working memory and the left hippocampus and frontal white matter in term subjects. While not correlated, memory scores and volumes of cortical regions known to subserve language and memory were reduced in preterm subjects. This study provides evidence of possible mechanisms for learning problems in former preterm infants.

from the Journal of Child Neurology

Other Impairment Associated With Developmental Language Delay in Preschool-Aged Children

The aim of this study was to investigate developmental impairment in several domains that might be associated with developmental language delay. The records of 56 preschool children with developmental language delay and 31 nonimpaired children were reviewed. Children with language delay were more likely than those in the nonimpaired group to have cognitive developmental delay (Mental Development Index < 70) (P < .001) and gross and fine motor delay (gross: 28 [50%] versus 5 [16%], P = .002; fine: 34 [62%] versus 11 [35%], P = .02). Children with language delay were significantly more likely to have impairment than were nonimpaired children in gross motor, fine motor, comprehension-conceptual and personal-social (P = .01, P = .02, P = .01, P = .02, respectively) functional domains. Our findings indicate that preschool children with language delay have wide-ranging difficulties in development and function.

from the Journal of Child Neurology

Evoked response audiometry in scrub typhus: prospective, randomised, case–control study

Conclusion: Findings were suggestive of retrocochlear pathology in two cases with normal hearing. In other patients, high frequency hearing loss may have led to altered evoked response results. Although scrub typhus appears to cause middle ear cochlear and retrocochlear damage, the presence of such damage could not be fully confirmed by evoked response audiometry.

from the Journal of Laryngology and Otology

Quality of life improvement for bone-anchored hearing aid users and their partners

Results and conclusions: Surveys were completed by 90 patients (58.8 per cent), of whom 72 reported having a partner. Partners reported a significant improvement in hearing (p ≤ 0.0001). Partners reported improvement in 87.0 per cent of functional scenarios, no change in 12.6 per cent, and a decline in 0.4 per cent. These findings demonstrate a significant improvement in the emotional and social effects of hearing impairment, as perceived by bone-anchored hearing aid recipients’ partners.

from the Journal of Laryngology and Otology

Soft tissue overgrowth in bone-anchored hearing aid patients: use of 8.5 mm abutment

Conclusion: The 8.5 mm bone-anchored hearing aid abutment is successful in preventing the need for additional surgical intervention in the small but significant number of patients with post-implantation soft tissue overgrowth. Early consideration should be given to this option when first-line soft tissue care is inadequate.

from the Journal of Laryngology and Otology

An EPG Study of Palatal Consonants in Two Australian Languages

This study presents EPG (electro-palatographic) data on (alveo-)palatal consonants from two Australian languages, Arrernte and Warlpiri. (Alveo-)palatal consonants are phonemic for stop, lateral and nasal manners of articulation in both languages, and are laminal articulations. However, in Arrernte, these lamino-(alveo-)palatals contrast with lamino-dental consonants for all three manners of articulation (i.e., it is a double-laminal language), whereas in Warlpiri this laminal contrast does not exist (i.e., it is a single-laminal language). Data are analyzed according to manner of articulation, vowel context and phrase position. Results suggest that in the double-laminal language Arrernte, the (alveo-)palatal articulation is further back than in the single-laminal language Warlpiri, presumably due to the presence of the lamino-dental in the Arrernte phoneme inventory. The lateral has the least contact in the back regions of the palate for both languages, but there is no significant difference in contact pattern between the stop and the nasal. However, results tentatively suggest that the nasal (alveo-)palatal is the most likely to show effects of prosodic or vocalic context, and it is suggested that this is due to the less strict airflow requirements for the nasal than for the stop or the lateral.

from Language and Speech

Articulation Rate in Childhood and Adolescence: Hebrew Speakers

This study aimed to quantify articulation rate among Hebrew speaking children and adolescents across a wide age range, and to assess whether age-related differences vary according to metric. One hundred and forty children, in seven age groups, participated in this cross-sectional study. All children were recorded during conversation and a picture description task, and articulation rate was measured using three metrics: word per minute (WPM), syllable per second (SPS) and phone per second (PPS). A significant increase in articulation rate was observed with age. Rate measurements during conversation were significantly faster than in picture description, and no gender differences were found. In general, the SPS and PPS metrics yielded equivalent results, which were different from those obtained with the WPM metric. Articulation rate among normally fluent children and adolescents increased with age. Furthermore, an increase in rate was evident after the age of 13 years.

from Language and Speech

Polynomial Modeling of Child and Adult Intonation in German Spontaneous Speech

In a data set of 291 spontaneous utterances from German 5-year-olds, 7-year-olds and adults, nuclear pitch contours were labeled manually using the GToBI annotation system. Ten different contour types were identified.The fundamental frequency (F0) of these contours was modeled using third-order orthogonal polynomials, following an approach similar to the one Grabe, Kochanski, and Coleman (2007) used for English. Statistical analyses showed that all but one contour pair differed significantly from each other in at least one of the four coefficients. This demonstrates that polynomial modeling can provide quantitative empirical support for phonological labels in unscripted speech, and for languages other than English. Furthermore, polynomial expressions can be used to derive the alignment of tonal targets relative to the syllable structure, making polynomial modeling more accessible to the phonological research community. Finally, within-contour comparisons of the three age groups showed that for children, the magnitude of the higher coefficients is lower, suggesting that they are not yet able to modulate their pitch as fast as adults.

from Language and Speech

Processing of No-release Variants in Connected Speech

The cross modal repetition priming paradigm was used to investigate how potential lexically ambiguous no-release variants are processed. In particular we focus on segmental regularities that affect the variant’s frequency of occurrence (voicing of the critical segment) and phonological context in which the variant occurs (status of the following word-initial segment). Primes consisted of carrier words ending in a segment likely (voiced; e.g., BAND) or unlikely (voiceless; PLANT) to be produced in no-release form followed by a consonant or vowel onset context word. Each carrier word had an embedded lexical competitor (embedded word) formed by the segments prior to its final consonant (e.g., plan in plant). Productions of these embedded words (true embedded word) were also used as primes. Both true embedded words (Experiments 1a—1c) and carrier words (Experiments 2a—2c) were used as visual targets. The results are discussed in terms of the contribution of probabilistic speech events to theories of spoken word recognition and lexical competition.

from Language and Speech