Auditory backward masking deficits in children with reading disabilities

Studies evaluating temporal auditory processing among individuals with reading and other language deficits have yielded inconsistent findings due to methodological problems () and sample differences. In the current study, seven auditory masking thresholds were measured in fifty-two 7- to 10-year-old children (26 diagnosed with reading disability [RD], 26 without reading disability). Hierarchic multiple regression analyses indicated that RD status predicted performance only in the backward-bandpass noise (p<.05) and backward notched-noise conditions (p<.05), suggesting both temporal and spectral auditory processing deficits. These results suggest that any auditory deficit associated with RD may be more complex than previously hypothesized.     

The duration component of the stress effect in stuttering

The purpose of the present study was to investigate whether there is a relationship between stuttering on stressed syllables and the duration of these syllables. Sixteen adults who stutter read a text consisting of 226 syllables. The relative stress of each syllable was rated, and syllables were categorized into long- and short-stressed syllables, unstressed syllables and intermediate syllables lying in-between. In order to isolate effects caused by within-word position from those caused by linguistic stress, syllables in initial and in subsequent positions were analyzed separately. In both word position categories stressed syllables were stuttered more often than unstressed syllables. Stuttering frequency of intermediate syllables seems to be in-between stressed and unstressed syllables, just as their stress level is rated in-between. Results regarding the duration of stressed syllables do not allow final conclusions.

Educational objectives: The reader will learn about and be able to describe (1) language factors related with stuttering events, (2) the stress effect in adults who stutter, and (3) methods to control for its confounding variables.     

Disruption of short-term memory by distractor speech: Does content matter?

Four experiments replicate the finding that auditory distractors that are lexically identical to the visual target items dramatically increase the irrelevant-speech effect on serial recall. This effect was previously attributed to interference of incompatible order cues. The present results suggest that a different interpretation of this effect is required. Experiment 2 replicates the order congruence effect observed by Hughes and Jones (2005), but shows that this effect is most likely due to an attenuation of interference that is caused by strategic attention shifts to the nominally irrelevant material. Experiments 3 and 4 show that the between-stream similarity effect generalizes to a condition in which the distractor items were drawn from the same category as the targets, but were not identical to them. By showing that nonacoustic distractor features can increase interference in serial recall of lists of supposedly “meaningless” items such as digits or consonants, the results are most consistent with models that postulate an integration of short-term and long-term memory such as the embedded-processes model and the feature model and are inconsistent with classical structural accounts of memory.     

Prolonged development of auditory skills: A role for perceptual anchoring?

Many auditory skills continue to develop beyond infancy and even into adolescence, but the factors underlying this prolonged development remain poorly understood. Of interest here is the contribution of on-line statistical learning of stimulus repetitions (anchoring) to the development of auditory spectral and temporal discrimination, as well as the potential contributions of auditory attention and working memory. Children, aged 6–13 years, as well as adults (age range: 21–33 years) were tested on auditory frequency and duration discrimination. Each type of discrimination was measured in two conditions (XAB and XXXAB) designed to afford different levels of anchoring by varying the number of repetitions of a standard stimulus (X) prior to the presentation of the test tone (A or B) in each trial. Auditory attention and working memory were also assessed. Whereas duration and frequency discrimination in either condition did not reach adult level prior to 11 years of age, the magnitude of the anchoring effect was similar across ages. These data suggest that perceptual anchoring matures prior to the attainment of adult-like discrimination thresholds. Likewise, neither attention nor working memory could account for the observed developmental trajectories. That auditory discrimination and anchoring follow dissociable developmental trajectories suggests that different factors might contribute to the development of each. We therefore conclude that although anchoring might be necessary for attaining good auditory discrimination, it does not account for the prolonged development of auditory frequency and duration discrimination in school-aged children.     

Perceptual load does not modulate auditory distractor processing

In vision, it is well established that the perceptual load of a relevant task determines the extent to which irrelevant distractors are processed. Much less research has addressed the effects of perceptual load within hearing. Here, we provide an extensive test using two different perceptual load manipulations, measuring distractor processing through response competition and awareness report. Across four experiments, we consistently failed to find support for the role of perceptual load in auditory selective attention. We therefore propose that the auditory system – although able to selectively focus processing on a relevant stream of sounds – is likely to have surplus capacity to process auditory information from other streams, regardless of the perceptual load in the attended stream. This accords well with the notion of the auditory modality acting as an ‘early-warning’ system as detection of changes in the auditory scene is crucial even when the perceptual demands of the relevant task are high.     

Continuous loudness response to acoustic intensity dynamics in melodies: Effects of melodic contour,tempo, and tonality

The aim of this work was to investigate perceived loudness change in response to melodies that increase (up-ramp) or decrease (down-ramp) in acoustic intensity, and the interaction with other musical factors such as melodic contour, tempo, and tonality (tonal/atonal). A within-subjects design manipulated direction of linear intensity change (up-ramp, down-ramp), melodic contour (ascending, descending), tempo, and tonality, using single ramp trials and paired ramp trials, where single up-ramps and down-ramps were assembled to create continuous up-ramp/down-ramp or down-ramp/up-ramp pairs. Twenty-nine (Exp 1) and thirty-six (Exp 2) participants rated loudness continuously in response to trials with monophonic 13-note piano melodies lasting either 6.4 s or 12 s. Linear correlation coefficients > .89 between loudness and time show that time-series loudness responses to dynamic up-ramp and down-ramp melodies are essentially linear across all melodies. Therefore, ‘indirect’ loudness change derived from the difference in loudness at the beginning and end points of the continuous response was calculated. Down-ramps were perceived to change significantly more in loudness than up-ramps in both tonalities and at a relatively slow tempo. Loudness change was also greater for down-ramps presented with a congruent descending melodic contour, relative to an incongruent pairing (down-ramp and ascending melodic contour). No differential effect of intensity ramp/melodic contour congruency was observed for up-ramps. In paired ramp trials assessing the possible impact of ramp context, loudness change in response to up-ramps was significantly greater when preceded by down-ramps, than when not preceded by another ramp. Ramp context did not affect down-ramp perception. The contribution to the fields of music perception and psychoacoustics are discussed in the context of real-time perception of music, principles of music composition, and performance of musical dynamics.     

Working memory predicts semantic comprehension in dichotic listening in older adults

Older adults have difficulty understanding spoken language in the presence of competing voices. Everyday social situations involving multiple simultaneous talkers may become increasingly challenging in later life due to changes in the ability to focus attention. This study examined whether individual differences in cognitive function predict older adults’ ability to access sentence-level meanings in competing speech using a dichotic priming paradigm. Older listeners showed faster responses to words that matched the meaning of spoken sentences presented to the left or right ear, relative to a neutral baseline. However, older adults were more vulnerable than younger adults to interference from competing speech when the competing signal was presented to the right ear. This pattern of performance was strongly correlated with a non-auditory working memory measure, suggesting that cognitive factors play a key role in semantic comprehension in competing speech in healthy aging.     

The sound of time: cross-modal convergence in the spatial structuring of time

In a new integration, we show that the visual-spatial structuring of time converges with auditory-spatial left-right judgments for time-related words. In Experiment 1, participants placed past and future-related words respectively to the left and right of the midpoint on a horizontal line, reproducing earlier findings. In Experiment 2, neutral and time-related words were presented over headphones. Participants were asked to indicate whether words were louder on the left or right channel. On critical experimental trials, words were presented equally loud binaurally. As predicted, participants judged future words to be louder on the right channel more often than past-related words. Furthermore, there was a significant cross-modal overlap between the visual-spatial ordering (Experiment 1) and the auditory judgments (Experiment 2), which were continuously related. These findings provide support for the assumption that space and time have certain invariant properties that share a common structure across modalities.     

Functional ear (a)symmetry in brainstem neural activity relevant to encoding of voice pitch: a precursor for hemispheric specialization?

Pitch processing is lateralized to the right hemisphere; linguistic pitch is further mediated by left cortical areas. This experiment investigates whether ear asymmetries vary in brainstem representation of pitch depending on linguistic status. Brainstem frequency-following responses (FFRs) were elicited by monaural stimulation of the left and right ear of 15 native speakers of Mandarin Chinese using two synthetic speech stimuli that differ in linguistic status of tone. One represented a native lexical tone (Tone 2: T2); the other, T2′, a nonnative variant in which the pitch contour was a mirror image of T2 with the same starting and ending frequencies. Two 40-ms portions of f₀ contours were selected in order to compare two regions (R1, early; R2 late) differing in pitch acceleration rate and perceptual saliency. In R2, linguistic status effects revealed that T2 exhibited a larger degree of FFR rightward ear asymmetry as reflected in f₀ amplitude relative to T2′. Relative to midline (ear asymmetry = 0), the only ear asymmetry reaching significance was that favoring left ear stimulation elicited by T2′. By left- and right-ear stimulation separately, FFRs elicited by T2 were larger than T2′ in the right ear only. Within T2′, FFRs elicited by the earlier region were larger than the later in both ears. Within T2, no significant differences in FFRS were observed between regions in either ear. Collectively, these findings support the idea that origins of cortical processing preferences for perceptually-salient portions of pitch are rooted in early, preattentive stages of processing in the brainstem.