Associations Between Speech Perception, Vocabulary, and Phonological Awareness Skill in School-Aged Children With Speech Sound Disorders

Purpose Prior studies report conflicting descriptions of the relationships between phonological awareness (PA), vocabulary, and speech perception in preschoolers with speech disorders. This study sought to determine the nature of these relationships in a sample of school-aged children with residual speech sound errors affecting /ɹ/. Method Participants included 110 children aged 7;0–17;4 (years;months) with residual errors impacting /ɹ/. Data on perceptual acuity and perceptual bias in an /ɹ/ identification task, receptive vocabulary, and PA were obtained. A theoretically and empirically motivated path model was constructed with vocabulary mediating the relationship between two measures of speech perception and PA. Model parameters were determined through maximum likelihood estimation with standard errors that were robust to nonnormality. Monte Carlo simulation was used to examine achieved power at the current sample size. Results The saturated path model explained 19% of the variance in PA. The direct path between age-adjusted perceptual acuity and PA was significant, as was the direct path between vocabulary and PA. Contrary to our hypothesis, there was no evidence in the current sample that vocabulary skill mediated the relationship between speech perception and PA. Each individual path was adequately powered at the current sample size. Conclusions The overall model provided evidence for a continued relationship between speech perception, measured by perceptual acuity of the sound in error, and PA in school-aged children with residual speech errors. Thus, measures of speech perception remain relevant to the assessment of school-aged children and adolescents in this population. Supplemental Material https://doi.org/10.23641/asha.13641275

Infants can outperform adults in pitch and timbre perception

Adults perceive pitch with fine precision, 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 three experiments, we tested the limits of pitch and timbre perception in 66 infants and 44 adults. Contrary to expectations, we found that infants surpassed adults in detecting subtle changes in pitch in the presence of random variations in timbre, and vice versa. The results indicate high fidelity of pitch and timbre coding in infants, implying that fully mature cortical processing is not necessary for accurate discrimination of these features. The surprising superiority of infants over adults may reflect a developmental trajectory for learning natural statistical covariations between pitch and timbre that improves coding efficiency in adults, but results in degraded perceptual acuity when expectations for such covariations are violated.

How frequency hopping suppresses pulse-echo ambiguity in bat biosonar

Big brown bats transmit wideband FM biosonar sounds that sweep from 55 to 25 kHz (first harmonic, FM1) and from 110 to 50 kHz (second harmonic, FM2). FM1 is required to perceive echo delay for target ranging; FM2 contributes only if corresponding FM1 frequencies are present. We show that echoes need only the lowest FM1 broadcast frequencies of 25 to 30 kHz for delay perception. If these frequencies are removed, no delay is perceived. Bats begin echo processing at the lowest frequencies and accumulate perceptual acuity over successively higher frequencies, but they cannot proceed without the low-frequency starting point in their broadcasts. This reveals a solution to pulse-echo ambiguity, a serious problem for radar or sonar. In dense, extended biosonar scenes, bats have to emit sounds rapidly to avoid collisions with near objects. But if a new broadcast is emitted when echoes of the previous broadcast still are arriving, echoes from both broadcasts intermingle, creating ambiguity about which echo corresponds to which broadcast. Frequency hopping by several kilohertz from one broadcast to the next can segregate overlapping narrowband echo streams, but wideband FM echoes ordinarily do not segregate because their spectra still overlap. By starting echo processing at the lowest frequencies in frequency-hopped broadcasts, echoes of the higher hopped broadcast are prevented from being accepted by lower hopped broadcasts, and ambiguity is avoided. The bat-inspired spectrogram correlation and transformation (SCAT) model also begins at the lowest frequencies; echoes that lack them are eliminated from processing of delay and no longer cause ambiguity.

The Selectivity of Musical Advantage

The OPERA hypothesis theorizes how musical experience heightens perceptual acuity to lexical tones. One missing element in the hypothesis is whether musical advantage is general to all or specific to some lexical tones. To further extend the hypothesis, this study investigated whether English musicians consistently outperformed English nonmusicians in perceiving a variety of Cantonese tones. In an AXB discrimination task, the musicians exhibited superior discriminatory performance over the nonmusicians only in the high level, high rising, and mid-level tone contexts. Similarly, in a Cantonese tone sequence recall task, the musicians significantly outperformed the nonmusicians only in the contour tone context but not in the level tone context. Collectively, the results reflect the selectivity of musical advantage—musical experience is only advantageous to the perception of some but not all Cantonese tones, and elements of selectivity can be introduced to the OPERA hypothesis. Methodologically, the findings highlight the need to include a wide variety of lexical tone contrasts when studying music-to-language transfer.

Auditory Perception and Ultrasound Biofeedback Treatment Outcomes for Children With Residual /ɹ/ Distortions: A Randomized Controlled Trial

Purpose This study evaluated whether outcomes from treatment, which includes ultrasound visual feedback (UVF), would be more or less effective when combined with auditory perception training for children with residual /ɹ/ errors. Method Children ages 8–16 years with /ɹ/ distortions participated in speech therapy that included real-time UVF of the tongue. Thirty-eight participants were randomized to speech therapy conditions that included a primary focus on articulation using UVF or a condition that included auditory perceptual training plus UVF (incorporating category goodness judgments and self-monitoring). Generalization of /ɹ/ production accuracy to untrained words was assessed before and after 14 hr of therapy. Additionally, the role of auditory perceptual acuity was explored using a synthetic /ɹ/–/w/ continuum. Results There was no difference between the treatment groups in rate of improvement of /ɹ/ accuracy (increase of 34% for each group; p = .95, η p 2 = .00). However, pretreatment auditory acuity was associated with treatment progress in both groups, with finer perceptual acuity corresponding to greater progress ( p = .015, η p 2 = .182). Conclusion Similar gains in speech sound accuracy can be made with treatment that includes UVF with or without auditory perceptual training. Fine-grained perceptual acuity may be a prognostic indicator with treatment. Supplemental Material https://doi.org/10.23641/asha.11886219

Regulation of perceptual learning by chronic chemogenetic manipulation of parvalbumin-positive interneurons

Parvalbumin-positive (PV+) interneurons are major regulators of adult experience-dependent plasticity. Acute manipulation of PV+ cell activity before learning alters the rate of acquisition of new skills, whereas transient inactivation of PV+ cells interferes with retrieval of previously learned information. However, the effects of sustained PV+ cell manipulation throughout training remain largely unknown. Using chemogenetics in rat auditory cortex during an adaptive sound disrimination task, here we show that PV+ cells exert bidirectional control over the rate of perceptual learning. Down-regulation of PV+ cell activity accelerated learning, but increasing their activity resulted in slower learning. However, both interventions led to reduced gains in perceptual acuity by the end of training relative to controls. Furthermore, longitudinal training performance was functionally correlated with measures of neural synchrony and stimulus-specific adaptation. These findings suggest that, whereas restricting PV+ cell activity may initially facilitate training-induced plasticity, a subsequent increase in PV+ cell activity is necessary to prevent further plastic changes and consolidate learning.