Continuous Tone Research Articles

Dynamics of the Auditory Continuity Illusion.

Illusions give intriguing insights into perceptual and neural dynamics. In the auditory continuity illusion, two brief tones separated by a silent gap may be heard as one continuous tone if a noise burst with appropriate characteristics fills the gap. This illusion probes the conditions under which listeners link related sounds across time and maintain perceptual continuity in the face of sudden changes in sound mixtures. Conceptual explanations of this illusion have been proposed, but its neural basis is still being investigated. In this work we provide a dynamical systems framework, grounded in principles of neural dynamics, to explain the continuity illusion. We construct an idealized firing rate model of a neural population and analyze the conditions under which firing rate responses persist during the interruption between the two tones. First, we show that sustained inputs and hysteresis dynamics (a mismatch between tone levels needed to activate and inactivate the population) can produce continuous responses. Second, we show that transient inputs and bistable dynamics (coexistence of two stable firing rate levels) can also produce continuous responses. Finally, we combine these input types together to obtain neural dynamics consistent with two requirements for the continuity illusion as articulated in a well-known theory of auditory scene analysis: responses persist through the noise-filled gap if noise provides sufficient evidence that the tone continues and if there is no evidence of discontinuities between the tones and noise. By grounding these notions in a quantitative model that incorporates elements of neural circuits (recurrent excitation, and mutual inhibition, specifically), we identify plausible mechanisms for the continuity illusion. Our findings can help guide future studies of neural correlates of this illusion and inform development of more biophysically-based models of the auditory continuity illusion.

Propranolol rescued secondary trauma induced by immediate extinction

<p id="p00005">One hallmark of posttraumatic stress disorder (PTSD) involves impairments in the ability to extinguish conditioned fear memory. Accumulating evidence suggests that extinction training that occurs shortly after fear conditioning is less effective than delayed extinction training in yielding long-term extinction memory, a phenomenon that is referred to as immediate extinction deficit (IED). However, unknown is whether the IED is just an aberration or continues to affect re-extinction. <p id="p00010">This study revealed that the early extinction intervention after severe trauma may not only fail to inhibit the fear response but also act as a secondary trauma which can continually damage the ability to extinguish fear memory. Propranolol may be a good candidate to repair such damage. Our findings improve our understanding of the pathogenesis of PTSD and outcomes of an early intervention and may be helpful for selecting appropriate and effective interventions after trauma exposure and avoid secondary trauma that is caused by the intervention itself. <p id="p00015">In Experiment 1, 32 Sprague-Dawley rats were randomly divided into four groups (Immediate-Extinction, Immediate-No Extinction, Delayed-Extinction, Delayed-No Extinction) and underwent a standard fear conditioning procedure in which they received five tone-footshock trials in chamber A. After either 1 h (immediate) or 24 h (delayed), half of the animals underwent 30 extinction trials (1^st extinction session) in chamber B where the tone was presented alone. The other half remained in chamber B without any tone or footshock (these animals served as a no-extinction control group). Twenty-four hours later, these rats underwent the 2^nd extinction session (re- extinction) in chamber B. Twenty-four hours after the 2^nd extinction session, the rats were once again returned to chamber B and tested for their fear response to four continuous tones. The fear response was assessed by freezing behavior, and the effect of the 1^st extinction session was assessed by the average freezing response across the first four trials of the 2^nd extinction session. Compared with rats in the delayed extinction group, recently conditioned rats exhibited significantly higher levels of fear in the 2^nd extinction session, although an equivalent decline in freezing was observed in both groups across the 1^st extinction session, suggesting that immediate extinction failed to maintain fear suppression the next day. Furthermore, after undergoing two extinction training sessions, rats in the immediate extinction group exhibited no significant reduction of freezing compared with the non-extinguished control during the retention test, suggesting that the deficit reappeared during re-extinction. <p id="p00020">The aim of Experiment 2 was to investigate whether the deficit that was induced by immediate extinction could be rescued by the β-adrenergic receptor antagonist propranolol. In Experiment 2, 20 Sprague-Dawley rats underwent the same procedures as the immediate extinction groups in Experiment 1, with the exception that they received saline or propranolol (10 mg/kg, i.p.) within minutes after fear conditioning. We found that one injection of propranolol immediately after fear acquisition rescued the deficit of re-extinction but not immediate extinction.

Diverse patterns of responsiveness to fine temporal features of acoustic signals in a temperate austral forest frog, Batrachyla leptopus (Batrachylidae)

ABSTRACT Phonotactic female and vocal male responses of frogs to advertisement calls have been shown to encompass broader ranges than those of variation of natural mate-attracting signals. Anuran aggressive calls contribute to expand the range of sound features significant for communication. Evoked vocal responses (EVRs) of males of Batrachyla leptopus to synthetic advertisement calls and variants with different temporal features altered parametrically were studied to assess their correspondence with features of natural signals. Frogs responded to stimuli differing in note rate with vocal patterns that depended on the design of the synthetic sounds: lower call rates were obtained with stimuli composed of notes with linear rise-fall times deviating from the average of this parameter for natural calls. However, opposite results were obtained with stimuli composed of sinusoidally amplitude-modulated notes. Calls of longer duration resembling aggressive calls were emitted in response to low note rate sinusoidal stimuli. Stimuli with note durations above and below the natural average, stimuli having low pulse rates and a continuous tone also elicited longer calls of aggressive type. These patterns relate the vocal responses recorded to recognition of conspecific and heterospecific advertisement and aggressive calls, as well as to novel signal features.

The onset of nonlinear growth of middle-ear responses to high intensity sounds

The human tympanic membrane (TM) and ossicles are generally considered to act as a linear system as they conduct low and moderate level environmental sounds to the cochlea. At intense stimulus levels (> 120 dB SPL) there is evidence that the TM and ossicles no longer act linearly. The anatomical structures that contribute to the nonlinear responses and their level and frequency dependences are not well defined. We used cadaveric human ears to characterize middle-ear responses to continuous tones between 200 and 20,000 Hz with levels between 60 and 150 dB SPL. The responses of the TM and ossicles are essentially sinusoidal, even at the highest stimulus level, but grow nonlinearly with increased stimulus level. The umbo and the stapes show different nonlinear behaviors: The umbo displacement grows faster than the stimulus level (expansive growth) at frequencies below 2000 Hz, while the stapes exhibits mostly compressive growth (grows slower than the stimulus level) over a wide frequency range. The sound pressure level where the nonlinearity first becomes obvious and the displacement at that level are lower at the stapes than at the umbo. These observations suggest the presence of multiple nonlinear processes within the middle ear. The existence of an expansive growth of umbo displacement that has limited effect on the stapes compressive growth suggests that the ossicular joints reduce the coupling between multiple nonlinear mechanisms within the middle ear. This study provides new data to test and refine middle-ear nonlinear models.

Perirhinal damage produces modality-dependent deficits in fear learning

The perirhinal cortex (PER) receives multimodal and unimodal sensory information from all modalities. In addition, the PER is anatomically connected with several brain regions that support fear learning. Several studies suggest that the PER is involved in fear conditioning to discontinuous auditory cues but not to continuous auditory cues. To date, studies examining the role of the PER in fear conditioning has largely focused on auditory and contextual stimuli. The present study assessed whether the role of the PER in fear conditioning would extend to visual modalities. Rodents were randomly assigned to one of four conditioned stimuli, which consisted of either a tone or a light stimulus that was either continuous or discontinuous. Pre-training excitotoxic lesions to the PER significantly reduced freezing to auditory and visual cues during the acquisition phase regardless of stimulus continuity. During subsequent testing, perirhinal lesions produced significant decreases in freezing levels to both continuous and discontinuous tones but not to either of the light CS groups. These results suggest that the PER is involved in the acquisition of fear across multiple cue modalities. However, the PER may have a more limited role in the retrieval of the fear memory dependent upon the cue modality.

Effects of prepulse format and lead interval on the assessment of automatic and attention-modulated prepulse inhibition.

Prepulse inhibition (PPI) of the acoustic startle response can index automatic and attention-modulated aspects of sensorimotor gating. Automatic sensorimotor gating is typically assessed by a no-task PPI protocol in which participants are presented with discrete white noise prepulse and startle stimuli over continuous background broadband noise at brief short-lead intervals (e.g., 60-120ms). In contrast, attention-modulated sensorimotor gating is typically assessed through a task-based PPI protocol using continuous format pure tone prepulses and white noise startle stimuli presented over an ambient background at a lead interval of 120ms. The present study sought to test the extent that the assessment of attention-modulated PPI is dependent on prepulse type and lead interval across two experiments. Experiment 1 assessed attention effects on PPI produced by discrete prepulses at lead intervals of 60 and 120ms. Experiment 2 examined attention effects on PPI with matched stimulus conditions apart from continuous prepulses. Results indicated that the use of discrete prepulses failed to elicit attentional-modulation of PPI and that assessment therein was dependent on the use of continuous prepulses at a lead interval of 120ms. These results highlight additional methods to concurrently assess automatic and attention-modulated PPI in a single testing session using a task-based tone counting task.

Spontaneous firing patterns in the medial geniculate nucleus in a guinea pig model of tinnitus

The mechanism of tinnitus, the perception of sound in the absence of acoustic stimulation, remains as yet unknown. It has been proposed that tinnitus is caused by altered spontaneous activity in the auditory pathway following cochlear damage in combination with inadequate gating at the level of the auditory thalamus, the medial geniculate nucleus (MGN). To investigate this further we made electrophysiological recordings in MGN of guinea pigs (n = 9) with and without tinnitus after acoustic trauma (continuous loud tone at 10 kHz, 124 dB SPL for 2 h). Parameters of interest were spontaneous tonic and burst firing. After acoustic trauma, 5 out of 9 guinea pigs developed signs of tinnitus as determined by the gap prepulse inhibition of acoustic startle. Spontaneous firing rates were significantly increased in the tinnitus animals as compared to the non-tinnitus animals and this change was specific to pure-tone responsive MGN neurons. However, burst firing parameters, including number of bursts per minute, burst duration, number of spikes in each burst, and percentage of spikes occurring in a burst, were not different between tinnitus and non-tinnitus animals. In addition, our data showed a strong dependence of spontaneous firing rates with heart rate, which implies that monitoring physiological status in animals is pertinent to obtaining reliable data when recording at higher levels of the auditory pathway. Our results suggest that increases in the tonic spontaneous fining rate of pure-tone responsive MGN neurons but not changes in burst firing parameters, are a robust neural signature of tinnitus in anaesthetised animals.

Pre-attentive auditory change detection for rapid auditory transient combinations: Insight from age-related processing changes

The N1 event-related potential (ERP) enhancement to auditory transients preceded briefly by another transient has been interpreted as a reflection of latent inhibition, or alternatively, as a superimposing mismatch negativity (MMN) to rare transient event combinations. In a previous study (Volosin, Gaál, & Horváth, 2017a), when rare glides preceded frequent gaps by 150 ms in continuous tones, gap-related N1 was enhanced in younger adults while P2 was attenuated both in younger and older adults, which could be parsimoniously explained by MMN overlap which was delayed with aging. The present study replicated and extended these results with a condition in which the roles of the two event types were reversed. Transients separated by 150 ms elicited delayed MMN in older adults, supporting the MMN interpretation over the latent inhibition account. Furthermore, the divergence of N1 and MMN elicitation patterns demonstrated the independence of N1 and MMN.

Distractor-induced deafness: The effect of multiple auditory distractors on conscious target processing

Conscious access to a target stimulus embedded in a rapid serial visual presentation can be impaired by the preceding presentation of multiple task-irrelevant distractors. While this phenomenon – labeled distractor-induced blindness (DIB) – is established in vision, it is unknown whether a similar effect can be observed in the auditory modality. Considering the differences in the processing of visual and auditory stimuli, modality-specific effects in the inhibitory mechanisms triggered by distractors can be expected. First, we aimed to find evidence for a distractor-induced deafness (DID) for auditory targets in a behavioral experiment. The target was defined by a transient increase in amplitude in a continuous sinusoidal tone, which was to be detected if accompanied or preceded by a deviant tone (cue). Both events were embedded in separate streams in a binaural rapid serial auditory presentation. Distractors preceded the cue and shared the target's features. As previously observed for DIB, a failure to detect the auditory target critically relied on the presentation of multiple distractor episodes. This DID effect was followed up in a subsequent event-related brain potentials (ERP) study to identify the signature of target detection. In contrast to missed targets, hits were characterized by a larger frontal negativity and by a more pronounced centro-parietal P3b wave. Whereas the latter process was also observed in the visual domain, indicating a post-perceptual updating process, the frontal negativity was exclusively observed for auditory DID. This modality-specific process might signal that early attentional control processes support conscious access to relevant auditory events.

3D Printing the Woodburytype &amp;#x2014; Plastic Printing the Plate or Gel Printing the Image?

The Woodburytype process is one of the only printing processes capable of producing continuous tone. It is a 2.5D process that produces a textured relief print from a gelatin-based ink that contains no photo-active element and therefore does not degrade with time. Despite all these advantages, the process is time consuming and requires the use of precision equipment to build the printing plate. We explore the initial insights into using more common additive manufacture technologies in producing both a printing plate and in ink characterization for selective deposition of the viscous gelatin ink itself.

Towards user-adapted training paradigms: Physiological responses to physical threat during cognitive task performance

Feedback of physiological responses have a great potential to support virtual training paradigms aimed to increase cognitive task performance under stressful threatening conditions. In the current study, we examined the sensitivity of a range of physiological indicators derived from electrodermal activity (EDA), blood pressure (BP) and heart rate (HR) to measure stress as induced by the threat of an electric shock (ES). In contrast to previous work that studied physiological stress responses compared to a rest condition, we compared conditions with high cognitive load combined with stress caused by threat of an ES, to conditions with high cognitive load without such stress. Twenty-five participants performed a cognitively demanding task in an experimental setup. At certain 10 s time intervals, indicated by a continuous tone, participants were either asked to do their best and increase cognitive task performance (non-threat condition), or they were told that they could receive an ES during this interval if cognitive task performance was not high enough (threat condition). Physiological measures, task performance and self-reported measures of stress and workload were analysed. Task performance and self-reported measures of stress and workload were roughly the same in both conditions. Especially EDA measures were affected by the threat of an ES. Threat and non-threat conditions could be distinguished with an across-participant classifier using EDA and BP features with an accuracy of 70%. These results suggest that EDA and BP can be used to evaluate stress coping training paradigms or to individually adapt the stress levels in virtual training environments. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.

Targeting the cholinergic anti-inflammatory pathway with vagus nerve stimulation in patients with Covid-19?

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), at the origin of the worldwide COVID-19 pandemic, is characterized by a dramatic cytokine storm in some critical patients with COVID-19. This storm is due to the release of high levels of pro-inflammatory cytokines such as interleukin (IL)-1 β, IL-6, tumor necrosis factor (TNF), and chemokines by respiratory epithelial and dendritic cells, and macrophages. We hypothesize that this cytokine storm and the worsening of patients’ health status can be dampened or even prevented by specifically targeting the vagal-driven cholinergic anti-inflammatory pathway (CAP). The CAP is a concept that involves an anti-inflammatory effect of vagal efferents by the release of acetylcholine (ACh). Nicotinic acetylcholine receptor alpha7 subunit (α7nAChRs) is required for ACh inhibition of macrophage-TNF release and cytokine modulation. Hence, targeting the α7nAChRs through vagus nerve stimulation (VNS) could be of interest in the management of patients with SARS-CoV-2 infection. Indeed, through the wide innervation of the organism by the vagus nerve, especially the lungs and gastrointestinal tract, VNS appears as a serious candidate for a few side effect treatment that could dampen or prevent the cytokine storm observed in COVID-19 patients with severe symptoms. Finally, a continuous vagal tone monitoring in patients with COVID-19 could be used as a predictive marker of COVID-19 illness course but also as a predictive marker of response to COVID-19 treatment such as VNS or others.

Alignment of Continuous Auditory and Visual Distractor Stimuli Is Leading to an Increased Performance

Information across different senses can affect our behavior in both positive and negative ways. Stimuli aligned with a target stimulus can lead to improved behavioral performances, while competing, transient stimuli often negatively affect our task performance. But what about subtle changes in task-irrelevant multisensory stimuli? Within this experiment we tested the effect of the alignment of subtle auditory and visual distractor stimuli on the performance of detection and discrimination tasks respectively. Participants performed either a detection or a discrimination task on a centrally presented Gabor patch, while being simultaneously subjected to a random dot kinematogram, which alternated its color from green to red with a frequency of 7.5 Hz and a continuous tone, which was either a frequency modulated pure tone for the audiovisual congruent and incongruent conditions or white noise for the visual control condition. While the modulation frequency of the pure tone initially differed from the modulation frequency of the random dot kinematogram, the modulation frequencies of both stimuli could align after a variable delay, and we measured accuracy and reaction times around the possible alignment time. We found increases in accuracy for the audiovisual congruent condition suggesting subtle alignments of multisensory background stimuli can increase performance on the current task.

Woodburytype: A historical process resurrected by modern methods

&#x0D; &#x0D; &#x0D; One of the technological achievements of the 19th century was the mass reproduction of photographic images. Woodburytype was thefirst commercially successful photomechanical continuous tone printing method, of unsurpassed quality until today. Along with Collotype and Goupil gravure, it used the relief of dichromated gelatin exposed to light as the basis for the printing plates. In this article we will discuss the historical printing processes and present how a) modern embodiments of the printing plates can be made by either CNC milling or using photopolymer plates and b) how optimal contrast and grayscale can be achieved by ink formulations tuned to the relief depth of the printing plate.&#x0D; &#x0D; &#x0D;

Single SH guided wave mode generation method for PPM EMATs**Project supported by the National Natural Science Foundation of China (Grant No. 51977044).

Using periodic permanent magnet (PPM) electromagnetic acoustic transducers (EMATs), different shear horizontal (SH) guided wave modes can form simultaneously in some situations, which can interfere with the inspection. The main cause of this phenomenon (typically named multiple modes) is related to the frequency bandwidth of excitation signals and the transducer spatial bandwidth. Simply narrowing the frequency bandwidth cannot effectively limit the number of different SH modes. Previous researches showed that unnecessary SH wave modes can be eliminated by using dual EMATs. However, in practical applications, it is more convenient to change the excitation frequency than to use dual EMATs. In this paper, the stress boundary conditions of the PPM-EMAT are analyzed, the analytical expression of SH guided wave is established, and the magnitude of SH guided wave mode under continuous tone and tone-burst input is obtained. A method to generate a single SH mode by re-selecting an operating point is proposed. Furthermore, the influence of the frequency bandwidth of the tone-burst signal is analyzed. Finally, a single SH mode excitation is achieved with tone-burst input.

Auditory pitch glides influence time-to-contact judgements of visual stimuli.

A common experimental task used to study the accuracy of estimating when a moving object arrives at a designated location is the time-to-contact (TTC) task. The previous studies have shown evidence that sound motion cues influence TTC estimates of a visual moving object. However, the extent to which sound can influence TTC of visual targets still remains unclear. Some studies on the crossmodal correspondence between pitch and speed suggest that descending pitch sounds are associated with faster speeds compared to ascending pitch sounds due to an internal model of gravity. Other studies have shown an opposite pitch-speed mapping (i.e., ascending pitch associated with faster speeds) and no influence of gravity heuristics. Here, we explored whether auditory pitch glides, a continuous pure tone sound either ascending or descending in pitch, influence TTC estimates of a vertically moving visual target and if any observed effects are consistent with a gravity-centered or gravity-unrelated pitch-speed mapping. Subjects estimated when a disc moving either upward or downward at a constant speed reached a visual landmark after the disc disappeared behind an occluder under three conditions: with an accompanying ascending pitch glide, with a descending pitch glide, or with no sound. Overall, subjects underestimated TTC with ascending pitch glides and overestimated TTC with descending pitch glides, compared to the no-sound condition. These biases in TTC were consistent in both disc motion directions. These results suggest that subjects adopted a gravity-unrelated pitch-speed mapping where ascending pitch is associated with faster speeds and descending pitch associated with slower speeds.

Illusory perception of auditory filled duration is task- and context-dependent.

In filled-duration illusion, a continuous (long) tone or an auditory sequence with multiple clicks is typically perceived as longer than the same physical duration (i.e., empty interval) enclosed by two auditory clicks. The auditory sequence is composed of multiple empty intervals. However, the individual empty interval in an auditory sequence, compared with the empty interval presented alone, could be biased in duration perception. In the current study, we implemented five experiments to reveal that the time perception of a single empty interval versus that of (mean) empty intervals in an auditory sequence depends on the task demands and contextual information. Specifically, we observed that the empty interval (140ms) was perceived as longer than the same physical inter-stimulus interval in a sound sequence (Experiments 1 and 3). However, the empty interval (140ms) was perceived as shorter than a continuous beep (i.e., filled duration of 140ms) (Experiment 2). We observed a robust compression effect, in which the target empty interval (bounded by two oddball clicks) was perceived as shorter than the other physically equivalent intervals in a sound sequence (Experiment 4). In addition to the 'compression', perception of the target empty interval was assimilated by the other, task-irrelevant empty intervals in the sound sequence (Experiment 5). We explained the observed contextually modulated temporal illusions within a Bayesian inference framework.

The one-is-more illusion: Sets of discrete objects appear less extended than equivalent continuous entities in both space and time

We distinguish between discrete objects and continuous entities in categorization and language, but might we actually see such stimuli differently? Here we report the one-is-more illusion, wherein ‘objecthood’ changes what we perceive in an unexpected way. Across many variations and tasks, observers perceived a single continuous object (e.g. a rectangle) as longer than an equated set of multiple discrete objects (e.g. two shorter rectangles separated by a gap). This illusion is phenomenologically compelling, exceptionally reliable, and it extends beyond space, to time: a single continuous tone is perceived to last longer than an equated set of multiple discrete tones. Previous work has emphasized the importance of objecthood for processes such as attention and visual working memory, but these results typically require careful analyses of subtle effects. In contrast, we provide striking demonstrations of how perceived objecthood changes the perception of other properties in a way that you can readily see (and hear!) with your own eyes (and ears!).

Characterizing acoustic propagation within the approach channel to Brandon Road Lock and Dam

A propagation experiment was conducted in the approach channel to the Brandon Road Lock and Dam on the Des Plaines River in Joliet, Illinois, over the course of ten days in 2017. A sequence of frequency sweeps, continuous tones, and white noise was broadcast from an underwater transducer deployed from a shallow draft workboat at nine locations within the channel. A vertical array of one tri-axial particle motion sensor and three hydrophones was deployed from a movable platform and recorded signals throughout the approach channel. An additional bottom mounted, autonomous recorder with one hydrophone and one particle motion sensor was deployed outside of the navigable channel for the duration of the experiment. The engineered channel includes cement walls and floors near the steel lock doors, transitioning to natural surface shoreline down channel. For sources or receivers near the lock, the highly reverberant interfaces dominate propagation effects. This presentation will compare results of the measurement experiment with propagation models.

Effects of auditory feedback on movements with two-segment sequence and eye–hand coordination

The present study investigated the effect of auditory feedback on planning and control of two-segment reaching movements and eye-hand coordination. In particular, it was examined whether additional auditory information indicating the progression of the initial reach (i.e., passing the midway and contacting the target) affects the performance of that reach and gaze shift to the second target at the transition between two segments. Young adults performed a rapid two-segment reaching task, in which both the first and second segments had two target sizes. One out of three auditory feedback conditions included the reach-progression information: a continuous tone was delivered at a consistent timing during the initial reach from the midway to the target contact. Conversely, the other two were control conditions: a continuous tone was delivered at a random timing in one condition or not delivered in the other. The results showed that the initial reach became more accurate with the auditory reach-progression cue compared to without any auditory cue. When that cue was available, movement time of the initial reach was decreased, which was accompanied by an increased peak velocity and a decreased time to peak velocity. These findings suggest that the auditory reach-progression feedback enhanced the preplanned control of the initial reach. Deceleration time of that reach was also decreased with auditory feedback, but it was observed regardless of whether the sound contained the reach-progression information. At the transition between the two segments, the onset latencies of both the gaze shift and reach to the second target became shorter with the auditory reach-progression cue, the effect of which was pronounced when the initial reach had a higher terminal accuracy constraint. This suggests that the reach-progression cue enhanced verification of the termination of initial reach, thereby facilitating the initiation of eye and hand movements to the second target. Taken together, the additional auditory information of reach-progression enhances the planning and control of multi-segment reaches and eye-hand coordination at the segment transition.