Primary and multisensory cortical activity is correlated with audiovisual percepts

Incongruent auditory and visual stimuli can elicit audiovisual illusions such as the McGurk effect where visual /ka/ and auditory /pa/ fuse into another percept such as/ta/. In the present study, human brain activity was measured with adaptation functional magnetic resonance imaging to investigate which brain areas support such audiovisual illusions. Subjects viewed trains of four movies beginning with three congruent /pa/ stimuli to induce adaptation. The fourth stimulus could be (i) another congruent /pa/, (ii) a congruent /ka/, (iii) an incongruent stimulus that evokes the McGurk effect in susceptible individuals (lips /ka/ voice /pa/), or (iv) the converse combination that does not cause the McGurk effect (lips /pa/ voice/ ka/). This paradigm was predicted to show increased release from adaptation (i.e. stronger brain activation) when the fourth movie and the related percept was increasingly different from the three previous movies. A stimulus change in either the auditory or the visual stimulus from /pa/ to /ka/ (iii, iv) produced within-modality and cross-modal responses in primary auditory and visual areas. A greater release from adaptation was observed for incongruent non-McGurk (iv) compared to incongruent McGurk (iii) trials. A network including the primary auditory and visual cortices, nonprimary auditory cortex, and several multisensory areas (superior temporal sulcus, intraparietal sulcus, insula, and pre-central cortex) showed a correlation between perceiving the McGurk effect and the fMRI signal, suggesting that these areas support the audiovisual illusion. Hum Brain Mapp, 2009. © 2009 Wiley-Liss, Inc.

from Human Brain Mapping

Auditory Steady-State Evoked Responses for Preterm and Term Neonates

Hearing thresholds were estimated in normal-hearing term and preterm neonates of <35 weeks of age using multiple-stimulus auditory steady-state responses (ASSRs). The tresholds, expressed in decibel sound pressure level, at signal frequencies of 500, 1000, 2000 and 4000 Hz were 44.30 ± 9.88, 27.80 ± 6.79, 26.77 ± 6.09 and 32.87 ± 6.12 for the term group and 49.11 ± 9.44, 26.38 ± 6.59, 26.74 ± 7.57 and 35.90 ± 8.23 for the preterm group. Significant threshold differences were measured between the groups at 500 and 4000 Hz, while the thresholds at 1000 and 2000 Hz were similar. The signal and noise levels as well as signal-to-noise ratio of responses were also measured and found to be similar. These results indicate that ASSRs can be effectively measured with a similar signal-to-noise ratio in both groups, but that there is a significant maturational effect occurring during gestation at the level of structures which participate in the formation of the ASSR at 500 and 4000 Hz.

from Audiology & Neuro-Otology

Auditory Steady-State Evoked Responses for Preterm and Term Neonates

Hearing thresholds were estimated in normal-hearing term and preterm neonates of <35 weeks of age using multiple-stimulus auditory steady-state responses (ASSRs). The tresholds, expressed in decibel sound pressure level, at signal frequencies of 500, 1000, 2000 and 4000 Hz were 44.30 ± 9.88, 27.80 ± 6.79, 26.77 ± 6.09 and 32.87 ± 6.12 for the term group and 49.11 ± 9.44, 26.38 ± 6.59, 26.74 ± 7.57 and 35.90 ± 8.23 for the preterm group. Significant threshold differences were measured between the groups at 500 and 4000 Hz, while the thresholds at 1000 and 2000 Hz were similar. The signal and noise levels as well as signal-to-noise ratio of responses were also measured and found to be similar. These results indicate that ASSRs can be effectively measured with a similar signal-to-noise ratio in both groups, but that there is a significant maturational effect occurring during gestation at the level of structures which participate in the formation of the ASSR at 500 and 4000 Hz.

from Audiology & Neuro-Otology

Implementation of neonatal screening for hearing impairment: Influence on pediatric otitis media surgery in The Netherlands

Conclusion
There seems to be an association between the implementation of neonatal screening for hearing impairment and the treatment of otitis media. During the whole studied period there was a slight but statistical significant increase in the odds for tube placement in all children aged 0–23 months. After implementation of the neonatal screen there was a distinct increase in the number of children aged 6–11 months treated with tubes. In the same period a statistical significant decline in the odds of undergoing adenoidectomy was observed.

from the International Journal of Pediatric Otorhinolaryngology

Topographical and Cellular Distribution of Perineuronal Nets in the Human Cochlear Nucleus

Specialized constructs of the extracellular matrix termed perineuronal nets surround the soma, primary dendrites and initial axon segment of some but not all neuronal populations in the central nervous system. In an effort to determine the cellular localization of perineuronal nets in the human cochlear nucleus (CN), we first performed a quantitative morphometric study of the human CN. We provide evidence for a laminar organization in the human dorsal cochlear nucleus (DCN; including molecular, granular and deep layers) as in other laboratory animals. Additionally, we find that the human ventral cochlear nucleus (VCN) contains distinct octopus, stellate, globular and spherical bushy cell populations, as described in other species. Using wisteria floribunda histochemistry in five human brainstems, we identified perineuronal nets in the human cochlear nucleus. Perineuronal nets are associated with the vast majority of octopus and stellate cells in the caudal VCN. In the rostral VCN, dense perineuronal nets are associated with globular bushy cells and faint nets are associated with some spherical bushy cells and stellate cells. Few perineuronal nets are found in the DCN.

from Hearing Research

Correlations between reading, phonological awareness and auditory temporal processing

CONCLUSION: dyslexic children demonstrated poorer results in all tests when compared to their controls. However, there was no definitive evidence that their poor performance on the auditory temporal processing tests was directly related to their phonological awareness skills, or even to their reading skills.

from Pró-Fono Revista de Atualização Científica

Ten-year results of cartilage palisades versus fascia in eardrum reconstruction after surgery for sinus or tensa retraction cholesteatoma in children

Conclusions:
The cartilage palisade grafting technique appears superior with respect to prevention of long-term eardrum retraction. The occurrence of cholesteatoma recurrency and eardrum perforation seem to be independent of grafting material, although these results may be due to type 2 error (low number of ears). In sinus cholesteatoma surgery and in type III tympanoplasty, the long-term hearing results appear better when grafting cartilage palisades. Laryngoscope, 2009

from Laryngoscope

Binaural sluggishness precludes temporal pitch processing based on envelope cues in conditions of binaural unmasking

Binaural sluggishness refers to the binaural system’s inability to follow fast changes in the interaural configuration of the incoming sound stream. Several studies have measured binaural sluggishness by measuring signal detection in conditions of binaural unmasking when the interaural configuration of the masker is changed over time. However, it has been shown that, in conditions of binaural unmasking, binaural sluggishness also affects the perception of temporal changes in the properties of the signal (i.e., its frequency or level) and not just in the interaural configuration of the masker. By measuring the temporal modulation transfer function for sinusoidally modulated noise presented in conditions of binaural unmasking, the first experiment of the current study showed that, due to binaural sluggishness, the internal representation of binaurally unmasked sounds conveys little or no information about envelope fluctuations with rates within the pitch range (i.e., above 30 Hz). The second experiment measured the masked detection threshold for musical interval recognition in binaurally unmasked harmonic tones and showed that, in conditions of binaural unmasking, pitch wanes when the harmonics become unresolved by the cochlear filters. These results suggest that binaural sluggishness precludes temporal pitch processing based on envelope cues in binaurally unmasked sounds.

©2009 Acoustical Society of America

from the Journal of the Acoustical Society of America

Effects of temporal uncertainty and temporal expectancy on infants’ auditory sensitivity

Adults are more sensitive to a sound if they know when the sound will occur. In the present experiment, the effects of temporal uncertainty and temporal expectancy on infants’ and adults’ detection of a 1 kHz tone in a broadband noise were examined. In one experiment, masked sensitivity was measured with an acoustic cue and without an acoustic cue to possible tone presentation times. Adults’ sensitivity was greater for the cue than for the no-cue condition, while infants’ sensitivity did not differ significantly between the cue and no-cue conditions. In a second experiment, the effect of temporal expectancy was investigated. The detection advantage for sounds occurring at an expected (most frequent) time, over sounds occurring at unexpected (less frequent) times, was examined. Both infants and adults detected a tone better when it occurred before or at an expected time following a cue than when it occurred at a later time. Thus, despite the fact that the auditory cue did not improve infants’ sensitivity, it nonetheless provided the basis for temporal expectancies. Infants, like adults, are more sensitive to sounds that are consistent with temporal expectancy.

©2009 Acoustical Society of America.

from the Journal of the Acoustical Society of America

Further examination of pitch discrimination interference between complex tones containing resolved harmonics

Pitch discrimination interference (PDI) is an impairment in fundamental frequency (F0) discrimination between two sequentially presented complex (target) tones produced by another complex tone (the interferer) that is filtered into a remote spectral frequency region. Micheyl and Oxenham [J. Acoust. Soc. Am. 121, 1621–1631 (2007)] reported a modest PDI for target tones and interferers both containing resolved harmonics when the F0 difference between the two target tones (F0) was small. When the interferer was in a lower spectral region than the target, a much larger PDI was observed when F0 was large (14%–20%), and, under these conditions, performance in the presence of an interferer was worse than at smaller F0s. The present study replicated the occurrence of PDI for complex tones containing resolved harmonics for small F0s. In contrast to Micheyl and Oxenham’s findings, performance in the presence of an interferer always increased monotonically with increasing F0. However, when the interferer was in a lower spectral region than the target (and not vice versa), some subjects needed verbal instructions or modified stimuli to choose the correct cue, indicating an asymmetry in spontaneous obviousness of the correct listening cue across conditions.

©2009 Acoustical Society of America

from the Journal of the Acoustical Society of America

Intelligibility of interrupted sentences at subsegmental levels in young normal-hearing and elderly hearing-impaired listeners

Although listeners can partially understand sentences interrupted by silence or noise, and their performance depends on the characteristics of the glimpses, few studies have examined effects of the types of segmental and subsegmental information on sentence intelligibility. Given the finding of twice better intelligibility from vowel-only glimpses than from consonants [Kewley-Port et al. (2007). “Contribution of consonant versus vowel information to sentence intelligibility for young normal-hearing and elderly hearing-impaired listeners,” J. Acoust. Soc. Am. 122, 2365–2375], this study examined young normal-hearing and elderly hearing-impaired (EHI) listeners’ intelligibility of interrupted sentences that preserved four different types of subsegmental cues (steady-states at centers or transitions at margins; vowel onset or offset transitions). Forty-two interrupted sentences from TIMIT were presented twice at 95 dB SPL, first with 50% and second with 70% of sentence duration. Compared to high sentence intelligibility for uninterrupted sentences, interrupted sentences had significant decreases in performance for all listeners, with a larger decrease for EHI listeners. Scores for both groups were significantly better for 70% duration than for 50% but were not significantly different for the type of subsegmental information. Performance by EHI listeners was associated with their high-frequency hearing thresholds rather than with age. Together with previous results using segmental interruption, preservation of vowels in interrupted sentences provides greater benefit to sentence intelligibility compared to consonants or subsegmental cues.

©2009 Acoustical Society of America

from the Journal of the Acoustical Society of America

Perceptual recalibration of speech sounds following speech motor learning

The functional sensorimotor nature of speech production has been demonstrated in studies examining speech adaptation to auditory and/or somatosensory feedback manipulations. These studies have focused primarily on flexible motor processes to explain their findings, without considering modifications to sensory representations resulting from the adaptation process. The present study explores whether the perceptual representation of the /s-/ contrast may be adjusted following the alteration of auditory feedback during the production of /s/-initial words. Consistent with prior studies of speech adaptation, talkers exposed to the feedback manipulation were found to adapt their motor plans for /s/-production in order to compensate for the effects of the sensory perturbation. In addition, a shift in the /s-/ category boundary was observed that reduced the functional impact of the auditory feedback manipulation by increasing the perceptual “distance” between the category boundary and subjects’ altered /s/-stimuli—a pattern of perceptual adaptation that was not observed in two separate control groups. These results suggest that speech adaptation to altered auditory feedback is not limited to the motor domain, but rather involves changes in both motor output and auditory representations of speech sounds that together act to reduce the impact of the perturbation.

©2009 Acoustical Society of America

from the Journal of the Acoustical Society of America

The interaction of vocal characteristics and audibility in the recognition of concurrent syllables

In concurrent-speech recognition, performance is enhanced when either the glottal pulse rate (GPR) or the vocal tract length (VTL) of the target speaker differs from that of the distracter, but relatively little is known about the trading relationship between the two variables, or how they interact with other cues such as signal-to-noise ratio (SNR). This paper presents a study in which listeners were asked to identify a target syllable in the presence of a distracter syllable, with carefully matched temporal envelopes. The syllables varied in GPR and VTL over a large range, and they were presented at different SNRs. The results showed that performance is particularly sensitive to the combination of GPR and VTL when the SNR is 0 dB. Equal-performance contours showed that when there are no other cues, a two-semitone difference in GPR produced the same advantage in performance as a 20% difference in VTL. This corresponds to a trading relationship between GPR and VTL of 1.6. The results illustrate that the auditory system can use any combination of differences in GPR, VTL, and SNR to segregate competing speech signals.

©2009 Acoustical Society of America

from the Journal of the Acoustical Society of America

Language experience and consonantal context effects on perceptual assimilation of French vowels by American-English learners of French

Recent research has called for an examination of perceptual assimilation patterns in second-language speech learning. This study examined the effects of language learning and consonantal context on perceptual assimilation of Parisian French (PF) front rounded vowels /y/ and // by American English (AE) learners of French. AE listeners differing in their French language experience (no experience, formal instruction, formal-plus-immersion experience) performed an assimilation task involving PF /y, , u, o, i, , a/ in bilabial /rabVp/ and alveolar /radVt/ contexts, presented in phrases. PF front rounded vowels were assimilated overwhelmingly to back AE vowels. For PF //, assimilation patterns differed as a function of language experience and consonantal context. However, PF /y/ revealed no experience effect in alveolar context. In bilabial context, listeners with extensive experience assimilated PF /y/ to /ju/ less often than listeners with no or only formal experience, a pattern predicting the poorest /u-y/ discrimination for the most experienced group. An “internal consistency” analysis indicated that responses were most consistent with extensive language experience and in bilabial context. Acoustical analysis revealed that acoustical similarities among PF vowels alone cannot explain context-specific assimilation patterns. Instead it is suggested that native-language allophonic variation influences context-specific perceptual patterns in second-language learning.

©2009 Acoustical Society of America

from the Journal of the Acoustical Society of America

Psychometric functions for pure tone intensity discrimination: Slope differences in school-aged children and adults

Previous work on pure tone intensity discrimination in school-aged children concluded that children might have higher levels of internal noise than adults for this task [J. Acoust. Soc. Am. 120, 2777–2788 (2006)]. If true, this would imply that psychometric function slopes are shallower for children than adults, a prediction that was tested in the present experiment. Normal hearing children (5–9 yr) and adults were tested in a two-stage protocol. The first stage used a tracking procedure to estimate 71% correct for intensity discrimination with a gated 500 Hz pure tone and a 65 dB sound pressure level standard level. The mean and standard deviation of these tracks were used to identify a set of five signal levels for each observer. In the second stage of the experiment percent correct was estimated at these five levels. Psychometric functions fitted to these data were significantly shallower for children than adults, as predicted by the internal noise hypothesis. Data from both stages of testing are consistent with a model wherein performance is based on a stable psychometric function, with sensitivity limited by psychometric function slope. Across observers the relationship between slope and threshold conformed closely to predictions of a simple signal detection model.

from the Journal of the Acoustical Society of America