Auditory Illusion Research Articles

Eight-Month-Old Infants Are Susceptible to the Auditory Continuity Illusion.

The real world is full of noise and constantly overlapping sounds. However, our auditory system provides a solution to this, that is, the continuity illusion; when we hear a sound stream that is partially replaced by high-level noise, we can restore missing sound information and "fill in" the information as if it were smooth and continuous even against a background of noise. In the present study, we tested the preferences for familiar and novel melodies of 8-month-old infants after a 2-month memory retention interval following 1-week exposure to a specific melody. A preference for familiarity was seen not only when the melody was presented intact but also when it was periodically replaced by high-level noise, which elicits the continuity illusion in adults (Experiment 1). However, a trend toward preference for a novel melody was observed for stimuli periodically replaced by low-level noise that did not satisfy the ecological constraints for the elicitation of the illusion (Experiment 2). For the first time, this study showed that infants as young as 8 months of age are susceptible to the auditory continuity illusion. The study also revealed that the infants could recognize the melody they heard 2 months previously.

Humans use local spectrotemporal correlations to detect rising and falling pitch.

To discern speech or appreciate music, the human auditory system detects how pitch increases or decreases over time. However, the algorithms used to detect changes in pitch, or pitch motion, are incompletely understood. Here, using psychophysics, computational modeling, functional neuroimaging, and analysis of recorded speech, we ask if humans detect pitch motion using computations analogous to those used by the visual system. We adapted stimuli from studies of vision to create novel auditory correlated noise stimuli that elicited robust pitch motion percepts. Crucially, these stimuli possess no persistent features across frequency or time, but do possess positive or negative local spectrotemporal correlations in intensity. In psychophysical experiments, we found clear evidence that humans judge pitch direction based on both positive and negative spectrotemporal correlations. The observed sensitivity to negative correlations is a direct analogue of illusory "reverse-phi" motion in vision, and thus constitutes a new auditory illusion. Our behavioral results and computational modeling led us to hypothesize that human auditory processing employs pitch direction opponency. fMRI measurements in auditory cortex supported this hypothesis. To link our psychophysical findings to real-world pitch perception, we analyzed recordings of English and Mandarin speech and discovered that pitch direction was robustly signaled by the same positive and negative spectrotemporal correlations used in our psychophysical tests, suggesting that sensitivity to both positive and negative correlations confers ecological benefits. Overall, this work reveals that motion detection algorithms sensitive to local correlations are deployed by the central nervous system across disparate modalities (vision and audition) and dimensions (space and frequency).

Effect of Binaural Beats on Anxiety and Tolerance in Patients Undergoing Upper Gastrointestinal Endoscopy Without Sedation: A Randomized Controlled Trial.

Objective: Binaural beats, or the perceptual auditory illusions created when simultaneously presenting two similar frequencies to each ear separately, have been used to reduce anxiety in various procedures. Unfortunately, no prior study involved preprocedure binaural music exposure among patients undergoing upper gastrointestinal endoscopy, and this study sought to investigate its effect on anxiety and tolerance among participants undergoing sedation-free upper gastrointestinal endoscopy. Methods: The prospective, controlled, randomized trial included the participation of 96 Turkish patients aged between 18 and 70 years who were scheduled for an upper gastrointestinal endoscopy, regardless of sex or illness, and were divided randomly into two different groups to undergo endoscopy, namely, the binaural beats group (n = 48) and a control group (n = 48). Patients in the binaural beat music group wore headphones, and music was given 15 mins before endoscopy; however, no particular treatment was given for either group. Anxiety levels were assessed by using the State Trait Anxiety Inventory questionnaire, in addition to changes before and after endoscopy to measure patient satisfaction based on the physician's recorded numbers of retches noted by doctors as tolerance was documented and compared among both groups. Results: The results showed that following this procedure, in the music group, state scores remained significantly lower than before them (p = 0.016), compared with the control group (p > 0.05). There was no significant difference regarding changes in diastolic or systolic heart rate or blood pressure (p > 0.05). However, the procedure tolerance and satisfaction scores were significantly higher in the music group than those without music (p < 0.05). Conclusion: For patients undergoing upper gastrointestinal endoscopy, music with binaural beats was found to significantly reduce anxiety levels and increase patient tolerance, providing an alternative option to sedative medications as a potential sedative treatment option.Clinical trials registration number: NCT06114524.

Proximal auditory AR rehabilitation: system integration and wellness applications-from hearing support up toward vestibular rehabilitation.

We present a new rehabilitation system based on novel principles, which consists of an auditory augmented reality (AR) headset we originated. The auditory AR headset, which does not cover both ears, allows users to hear both Real and Virtual environmental sounds at the same time. It can also be used in combination with Hearing Aids. We have studied a system to support hearing-impaired people and conducted a test evaluation. The system was able to provide convenience akin to "reading glasses for sound" to those who had mild hearing disabilities. Furthermore, by combining the system with surrounding speakers, a completely novel virtual auditory illusion was created in which the sound image jumps into the ear and runs away. We name this "proximal auditory AR (PAAR)" system. This system directly affects the unconscious level of reflexes for maintaining a standing position and can generate very subtle body motion disturbance. Using this system, we can modulate the standing posture and observe the autonomic nerve system's ability to subliminally compensate for the disturbance, using a stabilometer that measures body sways by center of pressure (COP). We observed a significant difference in the declination of COP only when using the PAAR, which is combined with array speakers and the auditory AR headphone, compared using a conventional closed-type and a bone-conduction headphone. By analyzing such big data of physical movement through machine learning, we expect to realize new systems for diagnosis, rehabilitation, function maintenance, and fall prevention.

Amplitude‐Phase Dual‐Channel Encrypted Acoustic Meta‐Holograms

AbstractEncrypted acoustic meta‐holograms have potential applications in confidential acoustic information communication, noise control, acoustic cloaking, acoustic illusion, etc. Conventional encrypted optical and acoustic meta‐holograms only focus on the encrypted hologram in a single channel, viz. modulating spatial amplitude to project a holographic image. Here, the concept of an amplitude‐phase dual‐channel encrypted acoustic meta‐hologram (DrEAM) is proposed, capable of generating, encrypting, and decrypting both amplitude and phase holographic images. This unique concept of “phase holographic image” introduces a new degree of freedom for meta‐holograms, leading to dual‐channel encrypted acoustic holography. Acoustic metasurface with simultaneous amplitude and phase modulations is employed to realize this dual‐channel encryption. The findings may offer the possibility to increase the capacity of the encrypted acoustic meta‐holograms, which can lead to practical applications in, for example, multi‐channel acoustic field communications, complex noise control, and acoustic illusions.

Broadband acoustic illusion coating based on thin conformal metasurface

Acoustic metasurface with rationally distributed phase manipulating characteristic provides a promising platform to reshape the wavefront of scattering wave. Such acoustic illusion carpet suffers from limitation of narrow bandwidth and relatively large volume to contain the object to be hidden. Here, we propose and experimentally demonstrate broadband conformal acoustic illusion coatings composed of subwavelength-thick metacells that are designed by two types of modified Helmholtz resonators with 2π reflection phase. By deliberate design of reflection phase distributions of illusion coating, the reflected wavefront can be reshaped between trapezoid and triangles and vice versa. Furthermore, an enlarged illusion is obtained by this methodology. More importantly, the illusion behaviors are verified both numerically and experimentally from 3000Hz to 4500Hz, resulting in relatively broad bandwidth up to 40.5%, which is definitely of extreme importance for potential applications.

Auditory localization: a comprehensive practical review.

Auditory localization is a fundamental ability that allows to perceive the spatial location of a sound source in the environment. The present work aims to provide a comprehensive overview of the mechanisms and acoustic cues used by the human perceptual system to achieve such accurate auditory localization. Acoustic cues are derived from the physical properties of sound waves, and many factors allow and influence auditory localization abilities. This review presents the monaural and binaural perceptual mechanisms involved in auditory localization in the three dimensions. Besides the main mechanisms of Interaural Time Difference, Interaural Level Difference and Head Related Transfer Function, secondary important elements such as reverberation and motion, are also analyzed. For each mechanism, the perceptual limits of localization abilities are presented. A section is specifically devoted to reference systems in space, and to the pointing methods used in experimental research. Finally, some cases of misperception and auditory illusion are described. More than a simple description of the perceptual mechanisms underlying localization, this paper is intended to provide also practical information available for experiments and work in the auditory field.

Auditory illusions and Post-traumatic stress disorder: Sound test in a case-control study

Post-Traumatic Stress Disorder (PTSD) is a prevalent and disabling disorder with a high degree of comorbidity. Clinical studies have focused on hallucinations, which could be associated with the severity of the disorder and treatment resistance. Auditory illusions have received little attention so far, possibly because they are particularly difficult to assess. However, they may impact functioning, and underdiagnosis could impair prognosis. To provide a clearer understanding of PTSD psychopathology, this paper proposes to focus on these auditory illusions.A monocentric case-control study was conducted on 30 subjects with PTSD and 30 controls, based on an original design. False recognitions were estimated during a sound test created with a vocoder. Additionally, differences in emotional valence, dissociation, hyperarousal, and reliving were assessed.The study found that individuals with PTSD experience a higher frequency of auditory illusions compared to healthy controls (65% versus 20%, p < 0.001). Additionally, the emotional valence of these illusions was more negative in individuals with PTSD than in controls. The study also identified a correlation between dissociation symptoms, hyperarousal and reliving with auditory illusions.These findings are in line with neurobiological studies of PTSD, as well as cognitive predictive models, and support the hypothesis of a significant prevalence of auditory illusions in PTSD. Like hallucinations, auditory illusions may be influenced by dissociation. Although these results are preliminary, they suggest a need for further investigation into auditory illusions in PTSD and their effect on prognosis.

Auditory Spatial Illusion – A Psychoacoustic Study in Young Adults

The Franssen illusion, or Franssen effect (FE), is one of the auditory spatial illusions. Few studies have explored the FE, and the mechanisms underlying it remain unknown. The present study was conducted to clarify the FE occurrence with different tasks and presentation modes in young adults. It also sought to investigate possible neurophysiological similarities between interaural time difference (ITD) cue processing and FE perception. FE perception was evaluated using two different tasks and two presentation modes (i.e., insert phones and loudspeakers). Sound reflections (reverberation) were presented in the diffuse field (loudspeaker mode). ITD performance was investigated using different stimuli delivered via insert phones. No significant difference between the two FE perception tasks was found ( F 1,25 = 0.138, p = 0.713). However, the FE perception showed a significant difference between the two presentation modes (F 1,25 = 434.03, p &amp;lt; 0.001). Spearman’s correlation did not reveal a significant relationship between FE perception and ITD scores ( p &amp;gt; 0.05). The current findings show the importance of reverberation in the FE occurrence. Also, the non-significant correlation between the results of the behavioral binaural temporal resolution test and FE perception in young people with normal temporal resolution may indicate that room reflections (reverberation) complicate the ability to process ITDs (rather than poor ITD processing for the “steady state” portion of signal).

3D wave expansion solution in spherical multilayer structures for acoustic illusion

3D wave expansion solution in spherical multilayer structures for acoustic illusion

Dexamphetamine increased speech and visual unimodal illusions in healthy participants without affecting temporal binding window.

Stimuli received beyond a very short timeframe, known as temporal binding windows (TBWs), are perceived as separate events. In previous audio-visual multisensory integration (McGurk effect) studies, widening of TBWs has been observed in people with schizophrenia. The present study aimed to determine if dexamphetamine could increase TBWs in unimodal auditory and unimodal visual illusions that may have some validity as experimental models for auditory and visual hallucinations in psychotic disorders. A double-blind, placebo-controlled, counter-balanced crossover design with permuted block randomisation for drug order was followed. Dexamphetamine (0.45mg/kg, PO, q.d.) was administered to healthy participants. Phantom word illusion (speech illusion) and visual-induced flash illusion/VIFI (visual illusion) tests were measured to determine if TBWs were altered as a function of delay between stimuli presentations. Word emotional content for phantom word illusions was also analysed. Dexamphetamine significantly increased the total number of phantom words/speech illusions (p<0.01) for pooled 220-1100ms ISIs in kernel density estimation and the number of positive valence words heard (beta=2.20, 95% CI [1.86, 2.55], t=12.46, p<0.001) with a large effect size (std. beta=1.05, 95% CI [0.89, 1.22]) relative to placebo without affecting the TBWs. For the VIFI test, kernel density estimation for pooled 0-801ms ISIs showed a significant difference (p<0.01) in the data distributions of number of target flash (es) perceived by participants after receiving dexamphetamine as compared with placebo. Overall, healthy participants who were administered dexamphetamine (0.45mg/kg, PO, q.d.) experienced increases in auditory and visual illusions in both phantom word illusion and VIFI tests without affecting their TBWs.

A disjointed account of the illusion of auditory continuity: in favor of hearing everyday sounds but against hearing semantic properties

ABSTRACT I will investigate the auditory illusion of continuity, which is the phenomenon of auditory occlusion in which we are able to hear a sound as continuous even though it has been masked by another sound. This phenomenon seems to have a perceptual nature when it occurs in the context of everyday sounds, while it seems to have a cognitive nature when it occurs in the context of speech sounds. This difference has the following consequences: (1) We need to have a differentiated approach to the study of this phenomenon; (2) the perceptual explanation of the phenomenon involving everyday sounds indicates that everyday sounds can be auditorily perceived; and (3) the cognitive explanation of the phenomenon involving speech sounds suggests, instead, that semantic properties cannot be auditorily perceived. From (2) and (3) it follows that while we have a good argument for the rich view when focusing on everyday sounds, we seem to lack an analogous argument to support the rich view in the context of speech sounds. Thus, I will suggest a new argument for the view that we do not hear semantic properties, as language understanding seems to be primarily a cognitive ability.

Binaural Beats and its Applications in Sports and Physical Exercise

The auditory illusion caused when two tones of similar frequencies are heard through stereo sound is called Binaural Beats and has been used in several areas, such as relaxation, attention and memory, mood regulation and more recently in the field of physical exercise. Thus, the aim of the study was to analyze the effects of Binaural Beats and its possible applications in sports and physical exercise. An integrative bibliographic review was carried out in the databases: PubMed, Scielo, Embase and SportDiscus. The descriptors used were Binaural Beats, OR Binaural Beating, OR Binaural Beat Therapy, OR Binaural auditory, OR Binaural frequency combined with Exercise, OR Physical activity, OR Sport. The search totaled 56 scientific studies (articles or abstracts) and four met the eligibility criteria being included and analyzed, showing that the use of Binaural Beats seems to contribute both to the improvement of performance and to recovery from exercise. However, it depends on the exposure time, frequency used and time of intervention.

Beta and gamma binaural beats enhance auditory sentence comprehension.

Binaural beats-an auditory illusion produced when two pure tones of slightly different frequencies are dichotically presented-have been shown to modulate various cognitive and psychological states. Here, we investigated the effects of binaural beat stimulation on auditory sentence processing that required interpretation of syntactic relations (Experiment 1) or an evaluation of syntactic well formedness (Experiment 2) with a large cohort of healthy young adults (N = 200). In both experiments, participants performed a language task after listening to one of four sounds (i.e., between-subject design): theta (7Hz), beta (18Hz), and gamma (40Hz) binaural beats embedded in music, or the music only (baseline). In Experiment 1, 100 participants indicated the gender of a noun linked to a transitive action verb in spoken sentences containing either a subject or object-relative center-embedded clause. We found that both beta and gamma binaural beats yielded better performance, compared to the baseline, especially for syntactically more complex object-relative sentences. To determine if the binaural beat effect can be generalized to another type of syntactic analysis, we conducted Experiment 2 in which another 100 participants indicated whether or not there was a grammatical error in spoken sentences. However, none of the binaural beats yielded better performance for this task indicating that the benefit of beta and gamma binaural beats may be specific to the interpretation of syntactic relations. Together, we demonstrate, for the first time, the positive impact of binaural beats on auditory language comprehension. Both theoretical and practical implications are discussed.

Octave illusion: stimulation frequencies can modulate perception.

The octave illusion (Deutsch, 1974) is a well-known auditory illusion elicited by presenting a dichotic sequence of two tones separated by an octave during which the high and low tones alternate between both ears. This illusion engages an important mechanism of auditory perception, which is pitch perception. Previous studies used central frequencies of the useful musical spectrum to elicit the illusion. However, these studies did not cover part of that spectrum where musical pitch perception decreases (below 200 and above 1600Hz). The present study aimed to investigate how the relative frequency distribution of percepts changes across a greater proportion of the musical scale to better understand the influence of pitch on illusion perception. Participants were presented with 7 pairs of frequencies from 40-80Hz to 2000-4000Hz and had to select a choice (octave, simple, complex) corresponding to their perception. When using pairs of stimuli towards the upper and lower boundaries of the selected range: (1) distributions of percepts significantly differ from the classic 400-800Hz, (2) the octave percept was reported less frequently, particularly at very low frequencies. Results from this study revealed that the illusion perception differs significantly at the low and high limits of the musical spectrum where reduced accuracy of pitch perception is known to occur. These results support past studies who investigated pitch perception. Furthermore, these results support the model proposed by Deutsch where pitch perception is one of the central frameworks of illusion perception.

Modifying Deutsch's scale illusion for application in music.

Deutsch's scale illusion demonstrates that the overall pitch range is the preferred organization when in competition with both local (note-to-note) pitch proximity and laterality (differences in the input ear). Such intricate factors can make it difficult to mimic this illusion. If a note is under a condition in which grouping by the overall pitch range and the local pitch proximity do not conflict, we hypothesized that an illusion would be perceived simply as the result of the competition between pitch proximity and laterality. In this paper, we aimed to replicate such a condition by modifying Deutsch's scale illusion. Psychophysical studies were conducted with healthy subjects. In the first half of the study, the C major scale with successive tones was presented in ascending form, alternating between the right and left ears; counterpart notes were simultaneously presented to the opposite ear, and the subjects were asked to listen to these dichotic tone patterns. Several counterpart notes were applied; we found that when the sequences of counterpart notes were close in note-to-note pitch proximity and were not overlapped with the ascending scale in pitch, the subjects appeared to perceive the scale clearly. In the latter half of the study, we applied this condition in music and devised auditory illusions such that melodies of the passages of "Lightly Row," "Cherry Blossoms," and "Jingle Bells" were perceived by listening to "jagged" dichotic tone patterns. The method we described in this paper is simple, and it is possible to easily create auditory illusions in music by applying our method.

Close Solution to Acoustic Illusion in Layered Media

Close Solution to Acoustic Illusion in Layered Media

Comparative evaluation of anxiety level during restorative treatment using no music, monaural beats, and binaural auditory beats as audio distraction behavior guidance technique in children aged 6-12 years: A randomized clinical trial.

Binaural auditory beat is an auditory illusion perceived when two different pure-tone sine waves with less than a 30 Hz difference are presented to a listener dichotically. Monaural beat stimulation is achieved by the superposition of amplitude-modulated signals of nearby frequencies to both ears simultaneously. The study aims to evaluate and compare anxiety level during restorative treatment using no music, monaural beats, and binaural auditory beats as audio distraction behavior guidance techniques in children aged 6-12 years. Three-arm, parallel-group randomized study was conducted in the department of pediatric and preventive dentistry. The sample size of 45 participants was calculated and allocated into three groups as no music, monaural beats, and binaural auditory beats group. Teeth with Class I cavity in primary or permanent molars were prepared and restored. Anxiety was measured pre and postintervention using pulse oximeter and Venham's picture test. Data obtained were analyzed with SPSS software version 20.0 and were carried out using one-way analysis of variance and dependent t-test and significance value < 0.05 was considered. Binaural auditory beats and monaural beats showed a better reduction in anxiety levels as per Venham's picture test scores with statistically significant "P" value 0.0001 and 0.064, respectively. Likewise, binaural auditory beats showed better reduction in anxiety levels as per pulse rate scores with statistically significant "P" value 0.0001 as compared to conventional treatment technique. Binaural auditory beat was found to be the most effective followed by the monaural beat compared to the control group. Thus, binaural auditory beats and monaural beats can be used effectively as an essential aid to reduce anxiety in children.

Towards Maximizing a Perceptual Sweet Spot for Spatial Sound With Loudspeakers

The <i>sweet spot</i> can be interpreted as the region where acoustic sources create a spatial auditory illusion. We study the problem of maximizing this sweet spot when reproducing a desired sound wave using an array of loudspeakers. To achieve this, we introduce a theoretical framework for spatial sound perception that can be used to define a sweet spot, and we develop a method that aims to generate a sound wave that directly maximizes the sweet spot defined by a model within this framework. Our method aims to incorporate perceptual principles from the onset and it is flexible: it imposes little to no constraints on the regions of interest, the arrangement of loudspeakers or their radiation pattern. However, the perceptual models must satisfy a convexity condition, which is fulfilled by state-of-the-art monaural perceptual models, but not by binaural ones. Proof-of-concept experiments show that our method, when implemented with van de Par&#x0027;s monaural model, outperforms state-of-the-art sound field synthesis methods in terms of their binaural azimuth localization and binaural coloration properties.

오순택 동시에 나타난 공기적 상상력

The poet, Oh Soon-taek pursues beauty, purity, and brightness, features of human’s nature in his children’s poetry. There are frangrances and sounds on the foundation of the beauty, purity, and brightness. He makes his readers dream new things and opens an entry for them to experience new world of imagination, through olfactory and auditory images. Fresh airy embodiment provides readers invigoration, definitely. Therefore, this study aims to analyze olfactory and auditory languages focusing on the entire poems of Oh Soon-taek and to trace airy imagination expressed in his children’s poetry. Though the poetic words related to fragrances are not signified in the poet’s works, he is not afraid of trying freely to olfactoryize hearing and to auditoryize olfaction. In addition, he is a subject who experiences more diverse auditory illusions than actual hearing and nature is like a mouth containing every auditory element to him. As mentioned above, the poet puts richly attractive fragrances and sounds in nature with his own imagination, and they are tied in his fantasy world as embodiment of infinite words and images in spite of no forms. Like this, Oh Soon-taek’s poetry showing the images of hearing and olfaction at the same time awake all things and make them live and breathe. There are fun as well as philosophy of life in the poet’s works. They open our eyes to forgotten realities and show freedom when feeling lightness from the materials offering happiness of small things. This is well expressed in Bell Sounds which hopes “all the sounds in the world will be pure like first cry of a newborn baby.” Sounds have no weight. Many things are put down, and then, there is a clean sound. How much this poem resounds! When reading the poet Oh Soon-taek’s poetry, our ears become clean. When we would rather hear it than read it through eyes, we seem to hear pure and bright sounds in the world. In addition, his collection of poems expressing love with fragrances contains lots of perfumes of flowers, grasses, and trees, awaking his readers’ olfactory sense. Someone says sounds last longest and fragrances last for a long and long time. His children’s poems reflecting universality of human emotions will be remembered as sounds or as fragrances to us.