Effects of Visually Induced Self-Motion on Sound Localization Accuracy

The deterioration of sound localization accuracy during a listener’s head/body rotation is independent of the listener’s rotation velocity (Honda et al., 2016). However, whether this deterioration occurs only during physical movement in a real environment remains unclear. In this study, we addressed this question by subjecting physically stationary listeners to visually induced self-motion, i.e., vection. Two conditions—one with a visually induced perception of self-motion (vection) and the other without vection (control)—were adopted. Under both conditions, a short noise burst (30 ms) was presented via a loudspeaker in a circular array placed horizontally in front of a listener. The listeners were asked to determine whether the acoustic stimulus was localized relative to their subjective midline. The results showed that in terms of detection thresholds based on the subjective midline, the sound localization accuracy was lower under the vection condition than under the control condition. This indicates that sound localization can be compromised under visually induced self-motion perception. These findings support the idea that self-motion information is crucial for auditory space perception and can potentially enable the design of dynamic binaural displays requiring fewer computational resources.

Effect of Road and Railway Sound on Psychological and Physiological Responses in an Office Environment

The present study aims to explore the psychophysiological impact of different traffic sounds in office spaces. In this experiment, 30 subjects were recruited and exposed to different traffic sounds in a virtual reality (VR) office scene. The road traffic sound and three railway sounds (conventional train, high-speed train, and tram) with three sound levels (45, 55, and 65 dB) were used as the acoustic stimuli. Physiological responses, electrodermal activity (EDA) and heart rate (HR) were monitored throughout the experiment. Psychological evaluations under each acoustic stimulus were also measured using scales within the VR system. The results showed that both the psychological and the physiological responses were significantly affected by the traffic sounds. As for psychological responses, considerable adverse effects of traffic sounds were observed, which constantly increased with the increase in the sound level. The peak sound level was found to have a better performance than the equivalent sound level in the assessment of the psychological impact of traffic sounds. As for the physiological responses, significant effects of both the acoustic factors (sound type and sound level) and the non-acoustic factors (gender and exposure time) were observed. The relationship between sound level and physiological parameters varied among different sound groups. The variation in sound level hardly affected the participants’ HR and EDA when exposed to the conventional train and tram sounds. In contrast, HR and EDA were significantly affected by the levels of road traffic sound and high-speed train sound. Through a correlation analysis, a relatively weak correlation between the psychological evaluations and HR was found.

Response triggering by an acoustic stimulus increases with stimulus intensity and is best predicted by startle reflex activation

In a simple reaction time task, the presentation of a startling acoustic stimulus has been shown to trigger the prepared response at short latency, known as the StartReact effect. However, it is unclear under what conditions it can be assumed that the loud stimulus results in response triggering. The purpose of the present study was to examine how auditory stimulus intensity and preparation level affect the probability of involuntary response triggering and the incidence of activation in the startle reflex indicator of sternocleidomastoid (SCM). In two reaction time experiments, participants were presented with an irrelevant auditory stimulus of varying intensities at various time points prior to the visual go-signal. Responses were independently categorized as responding to either the auditory or visual stimulus and those with or without SCM activation (i.e., SCM+/−). Both the incidence of response triggering and proportion of SCM+ trials increased with stimulus intensity and presentation closer to the go-signal. Data also showed that participants reacted to the auditory stimulus at a much higher rate on trials where the auditory stimulus elicited SCM activity versus those that did not, and a logistic regression analysis confirmed that SCM activation is a reliable predictor of response triggering for all conditions.

Considerations on tinnitus retraining therapy and transcranial magnetic stimulation

Introduction. Tinnitus is a subjective perception of sound in the absence of an external acoustic stimulus. It has negative behavioral feelings associated, e.g., depression, insomnia, difficulty of concentration, anxiety, irritability, and panic. The feelings impact negatively on the social and economic life of individuals. Empirical data suggest that disorders in the auditory cortex and its neural pathways give rise to abnormal spontaneous activations associated with tinnitus. Understanding the causes remains challenging. However, the current hypothesis suggests that clusters of neural networks and subnetworks are involved in tinnitus generation. Central dynamic neuroplasticity induced by a peripheral loss of auditory input can cause tinnitus noise. To date, there is no widespread consensus about the most effective therapy for treating tinnitus. Objective. To reflect on two tinnitus therapies: Tinnitus Retraining Therapy (TRT) and Transcranial Magnetic Stimulation (TMS). Method. A narrative review. Explicit and systematic criteria were not adopted in searching for the theoretical framework. Results. TMS is promising compared to TRT because TMS acts on tinnitus neural mechanisms. TRT is effective on a behavioral level since it relieves mild and moderate tinnitus' negative feelings. Conclusion. TRT does not advance on the neural source, but only on the tinnitus perception. TMS acts directly on the neural causes. Both therapies have limitations and can work for some patients. However, the effect of TMS seems more efficient, although transient.

Expectations boost the reconstruction of auditory features from electrophysiological responses to noisy speech

Online speech processing imposes significant computational demands on the listening brain. Predictive coding provides an elegant account of the way this challenge is met through the exploitation of prior knowledge. While such accounts have accrued considerable evidence at the sublexical- and word-levels, relatively little is known about the predictive mechanisms that support sentence-level processing. Here, we exploit the 'pop-out' phenomenon (i.e. dramatic improvement in the intelligibility of degraded speech following prior information) to investigate the psychophysiological correlates of sentence comprehension. We recorded electroencephalography and pupillometry from 21 humans (10 females) while they rated the clarity of full sentences that had been degraded via noise-vocoding or sine-wave synthesis. Sentence pop-out was reliably elicited following visual presentation of the corresponding written sentence, despite never hearing the undistorted speech. No such effect was observed following incongruent or no written information. Pop-out was associated with improved reconstruction of the acoustic stimulus envelope from low-frequency EEG activity, implying that pop-out is mediated via top-down signals that enhance the precision of cortical speech representations. Spectral analysis revealed that pop-out was accompanied by a reduction in theta-band power, consistent with predictive coding accounts of acoustic filling-in and incremental sentence processing. Moreover, delta- and alpha-band power, as well as pupil diameter, were increased following the provision of any written information. We interpret these findings as evidence of a transition to a state of active listening, whereby participants selectively engage attentional and working memory processes to evaluate the congruence between expected and actual sensory input.

Genome-wide association study identifies new loci associated with noise-induced tinnitus in Chinese populations

Background Tinnitus is an auditory phantom sensation in the absence of an acoustic stimulus, which affects nearly 15% of the population. Excessive noise exposure is one of the main causes of tinnitus. To now, the knowledge of the genetic determinants of susceptibility to tinnitus remains limited. Results We performed a two-stage genome-wide association study (GWAS) and identified that two single nucleotide polymorphisms (SNPs), rs2846071 located in the intergenic region at 11q13.5 (odds ratio [OR] = 2.14, 95% confidence interval [CI] = 1.96–3.40, combined P = 4.89 × 10− 6) and rs4149577 located in the intron of TNFRSF1A gene at 12p13.31 (OR = 2.05, 95% CI = 1.89–2.51, combined P = 6.88 × 10− 6), are significantly associated with the susceptibility to noise-induced tinnitus. Furthermore, the expression quantitative trait loci (eQTL) analyses revealed that rs2846071 is significantly correlated with the expression of WNT11 gene, and rs4149577 with the expression of TNFRSF1A gene in multiple brain tissues (all P < 0.05). The newly identified candidate gene WNT11 is involved in Wnt pathway, and TNFRSF1A in the tumor necrosis factor pathway, respectively. Pathway enrichment analyses also showed that these two pathways are closely relevant to tinnitus. Conclusions Our findings highlight two novel loci at 11q13.5 and 12p13.31 conferring susceptibility to noise-induced tinnitus. and suggest that the WNT11 and TNFRSF1A genes might be the candidate causal targets of 11q13.5 and 12p13.31 loci, respectively.

Comparison of Sympathetic Skin Response (SSR) between Electrical and Acoustic Stimuli in a Healthy Pediatric Population

Data in the literature report that latency and morphology in the cutaneous sympathetic skin response (SSR) do not change according to the type of stimulus delivered, unlike the amplitude which shows greater values in relation to the intensity of the physical impact caused in patient. Since the acoustic stimulus represents a method better tolerated by the pediatric patient, the aim of this study is to evaluate the presence or absence of significant differences in SSR between electrical and acoustic stimuli. The SSR was performed for each child of 18 recruited in this study, deriving from the palm of the hand and the sole of the foot and initially delivering an electrical stimulus at the level of the median nerve at the wrist. Two acoustic stimuli were subsequently delivered with the aid of audiometric headphones. Our results show no significant differences for the amplitude values obtained (p values > 0.05). For the latency there was a statistically significant difference (p-value = 0.001) for the left hand, subsequently not confirmed by the comparison performed between the two sides (p-values = 0.28 and 0.56). If these preliminary data are confirmed by a larger sample, the acoustic stimulus could be introduced in a standardized protocol for performing SSR in pediatric patients.

SOCIAL INFORMATION AND BIOLOGICAL INVASIONS: CHORUS SONGS ARE MORE ATTRACTIVE TO EUROPEAN STARLINGS IN MORE RECENTLY ESTABLISHED POPULATIONS.

When biological invasions by animals occur, the individuals arriving in novel environments can be confronted with unpredictable or unfamiliar resources and may need social interaction to improve survival in the newly colonized areas. Gathering with conspecifics and using social information about their activities may reveal the location of suitable feeding and breeding sites. This could compensate for the absence of individual information about new habitats and constitute an advantage for new settlers. If a tendency to gather in response to social stimuli is transmitted from one generation to the next, and if the benefit of gathering is lower in long time established populations, there should be behavioural differences in receptivity to social cues in populations with different colonizing histories. We hypothesized that individuals of a social species like the European starling from relatively recently-established populations would be more responsive to social cues than individuals belonging to long-established populations. We conducted playback experiments using a starling chorus to test its acoustic attractiveness to populations of starlings with different colonizing histories. We compared the reaction of individuals from two populations in rural Brittany, western France, established for a long time, with three more recently settled ones: two populations from a propagation front in southern Italy and one urban population from Rennes city in Brittany. Our data supported our hypothesis: individuals from more recent populations were more responsive to the acoustic stimulus, and gave more calls in flight than individuals from populations with an older settlement history. We discuss the different behavioural responses we observed in the different populations and the potential effects of habitat characteristics and starling densities.

Calretinin Immunoreactivity in the VIIIth Nerve and Inner Ear Endorgans of Ranid Frogs

Calcium-binding proteins are essential for buffering intracellular calcium concentrations, which are critical for regulating cellular processes involved in neuronal computations. One such calcium-binding protein, calretinin, is present in many neurons of the central nervous system as well as those which innervate cranial sensory organs, although often with differential distributions in adjacent cellular elements. Here, we determined the presence and distribution of calretinin-immunoreactivity in the peripheral vestibular and auditory system of ranid frogs. Calretinin-immunoreactivity was observed in ganglion cells innervating the basilar and amphibian papilla, and in a subpopulation of ganglion cells innervating the saccular epithelium. In contrast, none of the ganglion cells innervating the lagena, the utricle, or the three semicircular canals were calretinin-immunopositive, suggesting that this calcium-binding protein is a marker for auditory but not vestibular afferent fibers in the frog. The absence of calretinin in vestibular ganglion cells corresponds with the lack of type I hair cells in anamniote vertebrates, many of which in amniotes are contacted by the neurites of large, calyx-forming calretinin-immunopositive ganglion cells. In the sensory epithelia of all endorgans, the majority of hair cells were strongly calretinin-immunopositive. Weakly calretinin-immunopositive hair cells were distributed in the intermediate region of the semicircular canal cristae, the central part of the saccular macula, the utricular, and lagenar striola and the medial part of the amphibian papilla. The differential presence of calretinin in the frog vestibular and auditory sensory periphery might reflect a biochemical feature related to firing patterns and frequency bandwidths of self-motion versus acoustic stimulus encoding, respectively.

Premovement inhibition protects motor actions from interference

Shortly before movement initiation, the corticospinal system undergoes a transient suppression. This phenomenon has been observed across a range of motor tasks, suggesting that it may be a obligatory component of movement preparation. We probed whether this was also the case when the urgency to perform a motor action was high, in a situation where little time was available to engage in preparatory processes. We controlled the urgency of an impending motor action by increasing or decreasing the foreperiod duration in an anticipatory timing task. Transcranial magnetic stimulation (TMS; experiment one) or a loud acoustic stimulus (LAS; experiment two) were used to examine how corticospinal and subcortical excitability were modulated during motor preparation. Preparatory inhibition of the corticospinal tract was absent when movement urgency was high, though motor actions were initiated on time. In contrast, subcortical circuits were progressively inhibited as the time to prepare increased. Interestingly, movement force and vigour were reduced by both TMS and the LAS when movement urgency was high, and enhanced when movement urgency was low. Our findings indicate that preparatory inhibition may not be a obligatory component of motor preparation. The behavioural effects we observed in the absence of preparatory inhibition were induced by both TMS and the LAS, suggesting that accessory sensory stimulation may disrupt motor output when such stimulation is presented in the absence of preparatory inhibition. We conclude that preparatory inhibition may be an adaptive strategy which can serve to protect the prepared motor action from external interference.