Comparing narrative storytelling ability in individuals with autism and fetal alcohol spectrum disorders.

BACKGROUND: Narrative discourse, or storytelling, is used in daily conversation and requires higher-level language and social communication skills that are not always captured by standardised assessments of language. Many autistic individuals and individuals with fetal alcohol spectrum disorders (FASD) have difficulties with both social communication and language skills, and narrative discourse analysis offers an ecologically relevant approach to assessing those challenges. AIMS: This study investigated narrative discourse in individuals with autism and FASD, as well as an age- and sex-matched comparison group. METHODS AND PROCEDURES: Narratives from 45 adolescents and adults, 11 with autism, 11 with FASD and 23 age- and sex-matched comparison participants were elicited using a wordless storybook. They were then transcribed orthographically, formatted to the Systematic Analyses of Language Transcript (SALT) convention and scored based on the SALT Narrative Scoring Scheme (NSS), a standardised language analysis protocol. In addition to the NSS total score, which assesses the overall structure and cohesion of the narratives produced, local and global measures of language ability were also employed. The local language measures included the number of mental state and temporal relation terms produced, while the global language measures included mean length of utterance, total different words, total words, total utterances, rate of speech, the number of mazes (e.g., repetitions, 'um', 'uh' or self-corrections) per total word and the NSS total score. OUTCOMES AND RESULTS: Using the SALT Language Sample Analysis tool, our results revealed that on global language measures, group differences were found on rate of speech, number of mazes per total words and the description of conflict/resolution in the narratives produced. The autism group produced significantly more mazes per total word and scored higher on the NSS conflict/resolution category score compared to the FASD and comparison groups. Both the autism and FASD groups spoke at a lower rate than the comparison group. On local language measures of narrative production, all groups were comparable, on average. CONCLUSIONS AND IMPLICATIONS: While many aspects of narrative discourse in the autism and FASD groups were similar to each other and to the comparison group, we observed group differences on global measures of narrative production and significant individual variability within groups, suggesting that narrative abilities considered at an individual level may provide important clinical information for intervention planning. Future research should also consider additional variables that influence narrative discourse, such as motivation, distractibility or decision-making of individual participants. WHAT THIS PAPER ADDS: What is already known on the subject Narrative discourse, or storytelling, is used in daily conversational interactions and reveals higher-level language skills that may not be well captured by standardised assessments of language. Many autistic individuals and individuals with fetal alcohol spectrum disorders (FASD) show difficulty with pragmatic and expressive language skills. What this paper adds to existing knowledge We found that many aspects of the narratives produced by the adolescents/young adults in the autism and FASD groups were comparable to each other and to the neurotypical group. However, the groups differed on three global measures of narrative production: rate of speech, number of mazes per total words and the description of conflict/resolution in the narratives produced. Also, significant variability was observed within groups, suggesting that narrative abilities should be considered at an individual level as opposed to their clinical groups. What are the potential or actual clinical implications of this work? This study showed that narrative discourse is an appropriate task that can be added to routine clinical assessments of language abilities in autistic adolescents/young adults as well as those with FASD or typical development and has the potential to reveal higher-level, real-world language skills. An important clinical implication of this study is that narrative language abilities should be considered at an individual level and individual-tailored interventions based on ability level due to the variability observed across individuals.

Superoptimal Perceptual Integration Suggests a Place-Based Representation of Pitch at High Frequencies.

Pitch, the perceptual correlate of sound repetition rate or frequency, plays an important role in speech perception, music perception, and listening in complex acoustic environments. Despite the perceptual importance of pitch, the neural mechanisms that underlie it remain poorly understood. Although cortical regions responsive to pitch have been identified, little is known about how pitch information is extracted from the inner ear itself. The two primary theories of peripheral pitch coding involve stimulus-driven spike timing, or phase locking, in the auditory nerve (time code), and the spatial distribution of responses along the length of the cochlear partition (place code). To rule out the use of timing information, we tested pitch discrimination of very high-frequency tones (>8 kHz), well beyond the putative limit of phase locking. We found that high-frequency pure-tone discrimination was poor, but when the tones were combined into a harmonic complex, a dramatic improvement in discrimination ability was observed that exceeded performance predicted by the optimal integration of peripheral information from each of the component frequencies. The results are consistent with the existence of pitch-sensitive neurons that rely only on place-based information from multiple harmonically related components. The results also provide evidence against the common assumption that poor high-frequency pure-tone pitch perception is the result of peripheral neural-coding constraints. The finding that place-based spectral coding is sufficient to elicit complex pitch at high frequencies has important implications for the design of future neural prostheses to restore hearing to deaf individuals.SIGNIFICANCE STATEMENT The question of how pitch is represented in the ear has been debated for over a century. Two competing theories involve timing information from neural spikes in the auditory nerve (time code) and the spatial distribution of neural activity along the length of the cochlear partition (place code). By using very high-frequency tones unlikely to be coded via time information, we discovered that information from the individual harmonics is combined so efficiently that performance exceeds theoretical predictions based on the optimal integration of information from each harmonic. The findings have important implications for the design of auditory prostheses because they suggest that enhanced spatial resolution alone may be sufficient to restore pitch via such implants.

Infant pitch perception: Missing fundamental melody discrimination.

Although recent results show that 3-month-olds can discriminate complex tones by their missing fundamental, it is arguable whether they are discriminating on the basis of a perceived pitch. A defining characteristic of pitch is that it carries melodic information. This study investigated whether 3-month-olds, 7-month-olds, and adults can detect a change in a melody composed of missing fundamental complexes. Participants heard a seven-note melody and learned to respond to a change that violated the melodic contour. To ensure that participants were responding on the basis of pitch, the notes in the melody had missing fundamentals and varied in spectral content on each presentation. In experiment I, all melodies had the same absolute pitch, while in experiment II, the melodies were randomly transposed into one of three different keys on each presentation. Almost all participants learned to ignore the spectral changes and respond to the changed note of the melody in both experiments, strengthening the argument that complex tones elicit a sense of musical pitch in infants. These results provide evidence that complex pitch perception is functional by 3 months of age.

Pupillometry shows the effort of auditory attention switching.

Successful speech communication often requires selective attention to a target stream amidst competing sounds, as well as the ability to switch attention among multiple interlocutors. However, auditory attention switching negatively affects both target detection accuracy and reaction time, suggesting that attention switches carry a cognitive cost. Pupillometry is one method of assessing mental effort or cognitive load. Two experiments were conducted to determine whether the effort associated with attention switches is detectable in the pupillary response. In both experiments, pupil dilation, target detection sensitivity, and reaction time were measured; the task required listeners to either maintain or switch attention between two concurrent speech streams. Secondary manipulations explored whether switch-related effort would increase when auditory streaming was harder. In experiment 1, spatially distinct stimuli were degraded by simulating reverberation (compromising across-time streaming cues), and target-masker talker gender match was also varied. In experiment 2, diotic streams separable by talker voice quality and pitch were degraded by noise vocoding, and the time alloted for mid-trial attention switching was varied. All trial manipulations had some effect on target detection sensitivity and/or reaction time; however, only the attention-switching manipulation affected the pupillary response: greater dilation was observed in trials requiring switching attention between talkers.

Perception of the pitch of unresolved harmonics by 3- and 7-month-old human infants.

Three-month-olds discriminate resolved harmonic complexes on the basis of missing fundamental (MF) pitch. In view of reported difficulty in discriminating unresolved complexes at 7 months and striking changes in the organization of the auditory system during early infancy, infants' ability to discriminate unresolved complexes is of some interest. This study investigated the ability of 3-month-olds, 7-month-olds, and adults to discriminate the pitch of unresolved harmonic complexes using an observer-based method. Stimuli were MF complexes bandpass filtered with a -12 dB/octave slope, combined in random phase, presented at 70 dB sound pressure level (SPL) for 650 ms with a 50 ms rise/fall with a pink noise at 65 dB SPL. The conditions were (1) "LOW" unresolved harmonics (2500-4500 Hz) based on MFs of 160 and 200 Hz and (2) "HIGH" unresolved harmonics (4000-6000 Hz) based on MFs of 190 and 200 Hz. To demonstrate MF discrimination, participants had to ignore spectral changes in complexes with the same fundamental and respond only when the fundamental changed. Nearly all infants tested categorized complexes by MF pitch suggesting discrimination of pitch extracted from unresolved harmonics by 3 months. Adults also categorized the complexes by MF pitch, although musically trained adults were more successful than musically untrained adults.

The prevalence and developmental course of auditory processing differences in autistic children.

Auditory processing differences, including hyper- or hyposensitivity to sound, aversions to sound, and difficulty listening under noisy, real-world conditions, are commonly reported in autistic individuals. However, the developmental course and functional impact of these auditory processing differences are unclear. In this study, we investigate the prevalence, developmental trajectory, and functional impact of auditory processing differences in autistic children throughout childhood using a longitudinal study design. Auditory processing differences were measured using the Short Sensory Profile, a caregiver questionnaire, in addition to adaptive behaviors and disruptive/concerning behaviors at 3, 6, and 9 years of age. Our results showed that auditory processing differences were reported in greater than 70% of the autistic children in our sample at all three timepoints, maintained a high prevalence through 9 years of age, and were associated with increased disruptive/concerning behaviors and difficulty with adaptive behaviors. Furthermore, in our sample of children, auditory processing differences at age 3 years predicted disruptive/concerning behaviors and difficulty with adaptive behaviors at age 9 years. These findings warrant further investigations of the potential benefit of incorporating measures of auditory processing during routine clinical evaluations as well as interventions targeting auditory processing differences in autistic children.

Perception of missing fundamental pitch by 3- and 4-month-old human infants.

A hallmark of complex pitch perception is that the pitch of a harmonic complex is the same whether or not the fundamental frequency is present. By 7 months, infants appear to discriminate on the basis of the pitch of the missing fundamental (MF). Although electrophysiological cortical responses to MF pitch changes have been recorded in infants younger than 7 months, no psychophysical studies have been published. This study investigated the ability of 3- and 4-month-olds to perceive the pitch of MF harmonic complexes based on fundamentals of 160 Hz and 200 Hz using an observer-based method. In experiment I, to demonstrate MF pitch discrimination, 3- and 4-month-olds were required to ignore spectral changes in complexes with the same fundamental and to respond only when the fundamental changed. In experiment II, a 60-260 Hz noise was presented with complexes to mask combination tones at the fundamental frequency. In experiment III, complexes were bandpass filtered with a -12 dB/octave slope to limit use of spectral edge cues and presented with a pink noise to mask all distortion products. Nearly all infants tested categorized complexes by MF pitch in these experiments, suggesting perception of the missing fundamental at 3 months.

The development of auditory temporal processing during the first year of life.

Objectives: The processing of auditory temporal information is important for the extraction of voice pitch, linguistic information, as well as the overall temporal structure of speech. However, many aspects of its early development remain poorly understood. This paper reviews the development of auditory temporal processing during the first year of life when infants are acquiring their native language. Methods: First, potential mechanisms of neural immaturity are discussed in the context of neurophysiological studies. Next, what is known about infant auditory capabilities is considered with a focus on psychophysical studies involving non-speech stimuli to investigate the perception of temporal fine structure and envelope cues. This is followed by a review of studies involving speech stimuli, including those that present vocoded signals as a method of degrading the spectro-temporal information available to infant listeners. Results/Conclusion: This review suggests that temporal resolution may be well developed in the first postnatal months, but that the ability to use and process the temporal information in an efficient way along the entire auditory pathway is longer to develop. Those findings have crucial implications for the development of language abilities, especially for infants with hearing impairment who are using cochlear implants.

Auditory Attention Deployment in Young Adults with Autism Spectrum Disorder.

Difficulty listening in noisy environments is a common complaint of individuals with autism spectrum disorder (ASD). However, the mechanisms underlying such auditory processing challenges are unknown. This preliminary study investigated auditory attention deployment in adults with ASD. Participants were instructed to maintain or switch attention between two simultaneous speech streams in three conditions: location (co-located versus ± 30° separation), voice (same voice versus male-female contrast), and both cues together. Results showed that individuals with ASD can selectively direct attention using location or voice cues, but performance was best when both cues were present. In comparison to neurotypical adults, overall performance was less accurate across all conditions. These findings warrant further investigation into auditory attention deployment differences in individuals with ASD.

Infant Pitch and Timbre Discrimination in the Presence of Variation in the Other Dimension.

Adult listeners perceive pitch with fine precision, with many adults capable of discriminating less than a 1 % change in fundamental frequency (F0). Although there is variability across individuals, this precise pitch perception is an ability ascribed to cortical functions that are also important for speech and music perception. Infants display neural immaturity in the auditory cortex, suggesting that pitch discrimination may improve throughout infancy. In two experiments, we tested the limits of F0 (pitch) and spectral centroid (timbre) perception in 66 infants and 31 adults. Contrary to expectations, we found that infants at both 3 and 7 months were able to reliably detect small changes in F0 in the presence of random variations in spectral content, and vice versa, to the extent that their performance matched that of adults with musical training and exceeded that of adults without musical training. The results indicate high fidelity of F0 and spectral-envelope coding in infants, implying that fully mature cortical processing is not necessary for accurate discrimination of these features. The surprising difference in performance between infants and musically untrained adults may reflect a developmental trajectory for learning natural statistical covariations between pitch and timbre that improves coding efficiency but results in degraded performance in adults without musical training when expectations for such covariations are violated.

Sustained Cortical and Subcortical Measures of Auditory and Visual Plasticity following Short-Term Perceptual Learning.

Short-term training can lead to improvements in behavioral discrimination of auditory and visual stimuli, as well as enhanced EEG responses to those stimuli. In the auditory domain, fluency with tonal languages and musical training has been associated with long-term cortical and subcortical plasticity, but less is known about the effects of shorter-term training. This study combined electroencephalography (EEG) and behavioral measures to investigate short-term learning and neural plasticity in both auditory and visual domains. Forty adult participants were divided into four groups. Three groups trained on one of three tasks, involving discrimination of auditory fundamental frequency (F0), auditory amplitude modulation rate (AM), or visual orientation (VIS). The fourth (control) group received no training. Pre- and post-training tests, as well as retention tests 30 days after training, involved behavioral discrimination thresholds, steady-state visually evoked potentials (SSVEP) to the flicker frequencies of visual stimuli, and auditory envelope-following responses simultaneously evoked and measured in response to rapid stimulus F0 (EFR), thought to reflect subcortical generators, and slow amplitude modulation (ASSR), thought to reflect cortical generators. Enhancement of the ASSR was observed in both auditory-trained groups, not specific to the AM-trained group, whereas enhancement of the SSVEP was found only in the visually-trained group. No evidence was found for changes in the EFR. The results suggest that some aspects of neural plasticity can develop rapidly and may generalize across tasks but not across modalities. Behaviorally, the pattern of learning was complex, with significant cross-task and cross-modal learning effects.

Infants' ability to perceive the pitch of unresolved harmonics.

An important phenomenon for models of pitch perception is that adult listeners can extract pitch from complexes containing only unresolved harmonics (UH). Although 3-month-olds discriminate resolved harmonics on the basis of missing fundamental (MF) pitch, their ability to discriminate UH is unknown. This study investigated the ability of adults, 7- and 3-month-olds to perceive the pitch of UH using an observer-based method. Stimuli were MF complexes that were bandpass filtered with a -12 dB/octave slope, combined in random phase, and presented at 70 dB SPL for 650 ms with a 50 ms rise/fall and a pink noise to mask distortion products. The experiment had two conditions: 1) "low" UH between 2500-4500 Hz based on MFs of 160 Hz (H17-H26) and 200 Hz (H13-H22) and 2) "high" UH between 4000-6000 Hz based on MFs of 190 Hz (H22-H31) and 200 Hz (H20-H29). To demonstrate MF pitch discrimination, participants were required to ignore spectral changes in complexes with the same fundamental and respond only when the fundamental changed. Interestingly, variable performance in the "high" condition was observed with adults. However, nearly all infants tested categorized complexes by MF pitch in both conditions, suggesting discrimination of unresolved harmonics at 3 months.