Masking Stimulus Research Articles

Spatial Release From Masking in Children: Effects of Simulated Unilateral Hearing Loss.

The purpose of this study was twofold: (1) to determine the effect of an acute simulated unilateral hearing loss on children's spatial release from masking in two-talker speech and speech-shaped noise, and (2) to develop a procedure to be used in future studies that will assess spatial release from masking in children who have permanent unilateral hearing loss. There were three main predictions. First, spatial release from masking was expected to be larger in two-talker speech than in speech-shaped noise. Second, simulated unilateral hearing loss was expected to worsen performance in all listening conditions, but particularly in the spatially separated two-talker speech masker. Third, spatial release from masking was expected to be smaller for children than for adults in the two-talker masker. Participants were 12 children (8.7 to 10.9 years) and 11 adults (18.5 to 30.4 years) with normal bilateral hearing. Thresholds for 50%-correct recognition of Bamford-Kowal-Bench sentences were measured adaptively in continuous two-talker speech or speech-shaped noise. Target sentences were always presented from a loudspeaker at 0° azimuth. The masker stimulus was either co-located with the target or spatially separated to +90° or -90° azimuth. Spatial release from masking was quantified as the difference between thresholds obtained when the target and masker were co-located and thresholds obtained when the masker was presented from +90° or -90° azimuth. Testing was completed both with and without a moderate simulated unilateral hearing loss, created with a foam earplug and supra-aural earmuff. A repeated-measures design was used to compare performance between children and adults, and performance in the no-plug and simulated-unilateral-hearing-loss conditions. All listeners benefited from spatial separation of target and masker stimuli on the azimuth plane in the no-plug listening conditions; this benefit was larger in two-talker speech than in speech-shaped noise. In the simulated-unilateral-hearing-loss conditions, a positive spatial release from masking was observed only when the masker was presented ipsilateral to the simulated unilateral hearing loss. In the speech-shaped noise masker, spatial release from masking in the no-plug condition was similar to that obtained when the masker was presented ipsilateral to the simulated unilateral hearing loss. In contrast, in the two-talker speech masker, spatial release from masking in the no-plug condition was much larger than that obtained when the masker was presented ipsilateral to the simulated unilateral hearing loss. When either masker was presented contralateral to the simulated unilateral hearing loss, spatial release from masking was negative. This pattern of results was observed for both children and adults, although children performed more poorly overall. Children and adults with normal bilateral hearing experience greater spatial release from masking for a two-talker speech than a speech-shaped noise masker. Testing in a two-talker speech masker revealed listening difficulties in the presence of disrupted binaural input that were not observed in a speech-shaped noise masker. This procedure offers promise for the assessment of spatial release from masking in children with permanent unilateral hearing loss.

Neural correlates of subliminally presented visual sexual stimuli.

In the context of forensic psychiatry, it is crucial that diagnoses of deviant sexual interests are resistant to manipulation. In a first attempt to promote the development of such tools, the current fMRI study focusses on the examination of hemodynamic responses to preferred, in contrast to non-preferred, sexual stimuli with and without explicit sexual features in 24 healthy heterosexual subjects. The subliminal stimulus presentation of sexual stimuli could be a new approach to reduce vulnerability to manipulation. Meaningful images and scrambled images were applied as masks. Recognition performance was low, but interestingly, sexual preference and explicitness modulated stimulus visibility, suggesting interactions between networks of sexual arousal and consciousness. With scrambled masks, higher activations for sexually preferred images and for explicit images were found in areas associated with sexual arousal (Stoleru, Fonteille, Cornelis, Joyal, & Moulier, 2012). We conclude that masked sexual stimuli can evoke activations in areas associated with supraliminal induced sexual arousal.

Attention Orienting in Response to Non-conscious Hierarchical Arrows: Individuals with Higher Autistic Traits Differ in Their Global/Local Bias.

One aspect of the social communication impairments that characterize autism spectrum disorder (ASD) include reduced use of often subtle non-verbal social cues. People with ASD, and those with self-reported sub-threshold autistic traits, also show impairments in rapid visual processing of stimuli unrelated to social or emotional properties. Hence, this study sought to investigate whether perceptually non-conscious visual processing is related to autistic traits. A neurotypical sample of thirty young adults completed the Subthreshold Autism Trait Questionnaire and a Posner-like attention cueing task. Continuous Flash Suppression (CFS) was employed to render incongruous hierarchical arrow cues perceptually invisible prior to consciously presented targets. This was achieved via a 10 Hz masking stimulus presented to the dominant eye that suppressed information presented to the non-dominant eye. Non-conscious arrows consisted of local arrow elements pointing in one direction, and forming a global arrow shape pointing in the opposite direction. On each trial, the cue provided either a valid or invalid cue for the spatial location of the subsequent target, depending on which level (global or local) received privileged attention. A significant autism-trait group by global cue validity interaction indicated a difference in the extent of non-conscious local/global cueing between groups. Simple effect analyses revealed that whilst participants with lower autistic traits showed a global arrow cueing effect, those with higher autistic traits demonstrated a small local arrow cueing effect. These results suggest that non-conscious processing biases in local/global attention may be related to individual differences in autistic traits.

Phonological-orthographic consistency for Japanese words and its impact on visual and auditory word recognition.

In most models of word processing, the degrees of consistency in the mappings between orthographic, phonological, and semantic representations are hypothesized to affect reading time. Following Hino, Miyamura, and Lupker's (2011) examination of the orthographic-phonological (O-P) and orthographic-semantic (O-S) consistency for 1,114 Japanese words (339 katakana and 775 kanji words), in the present research, we initially attempted to measure the phonological-orthographic (P-O) consistency for those same words. In contrast to the O-P and O-S consistencies, which were equivalent for kanji and katakana words, the P-O relationships were much more inconsistent for the kanji words than for the katakana words. The impact of kanji words' P-O consistency was then examined in both visual and auditory word recognition tasks. Although there was no effect of P-O consistency in the standard visual lexical-decision task, significant effects were detected in a lexical-decision task with auditory stimuli, in a perceptual identification task using masked visual stimuli, and in a lexical-decision task with degraded visual stimuli. The implications of these results are discussed in terms of the impact of P-O consistency in auditory and visual word recognition. (PsycINFO Database Record

Recognition of Emotional Facial Expressions in Alexithymia

The term Alexithymia (from Greek: lack of words for emotions), refers to a specific disturbance in affective-emotional processing that is manifested through following salient features: 1) difficulty in identifying and describing feelings and emotions verbally, 2) difficulty in distinguishing between feelings and somatic sensations that accompany emotional arousal, and 3) externally-oriented thinking and impaired symbolic activity (Taylor & Bagby, 2004). The most recent research has stressed point that in alexithymia there is not only a difficulty in expressing emotions verbally but also a deficit in cognitive processing of emotions (Berenbaum & Prince, 1994; Jessimer & Markham, 1997; Lundh & Simonsson-Sarnecki, 2002; Parker, Taylor, & Bagby, 1993; Roedema & Simons, 1999; Suslow, 1998; Suslow & Junghanns, 2002); as a consequence, emotions remain undifferentiated and poorly regulated (Taylor, Bagby, & Parker, 1991) and those afflicted are more likely to misinterpret their emotions as being symptoms of illness (Taylor & Bagby, 2004).First studied in classical psychosomatic or somatic disorders, alexithymia is known today as a personality trait (Martinez-Sanchez, Ato, Corcoles, Huedo, & Selva, 1998; MartinezSanchez, Ato, & Ortiz, 2003), normally distributed in general population with significantly higher levels in male subjects (Franz et al., 2008; Schimmenti, 2016). A high level of alexithymia is considered as a possible vulnerability factor for a variety of psychiatric disorders and physical illnesses (Taylor, Bagby, & Parker, 1997), such as substance use disorders, somatization, anxiety and depression, and even schizophrenia (Lumley, Neely, & Burger, 2007).Alexithymics appear to be less able to recognize their emotion signals and regulate emotions effectively (Taylor et al., 1997). Several studies demonstrated that alexithymic individuals are impaired in their ability to recognize emotion when both stimulus and response are non-verbal, suggesting that alexithymia, the lack of words for emotion, is not just a verbal phenomenon. Several authors hypothesized that hampered regulation of emotion in alexithymia might be based on deficits in perception and further processing of emotional stimuli (Aleman, 2005; Martinez-Sanchez, Montero, & de la Cerra, 2002; Lane, Sechrest, Reidel, Shapiro, & Kaszniak, 2000). This statement has been empirically supported by imaging data (Kano et al., 2003; Mantani, Okamoto, Shirao, Okada, & Yamawaki, 2005; Moriguchi et al., 2006) and event-related potentials (Pollatos & Gramann, 2011).One of most fruitful areas of investigation that has occupied investigation of alexithymia is study of patterns of recognition of facial expressions of emotion. It is well established that facial emotion recognition has an important place in emotion regulation, interpersonal communication skills, and in development of psycho-pathologies (Ozturk, Kilic, Deveci, & Kirpinar, 2016).In this line, previous studies have shown a significant correlation between alexithymia and a lack of ability to recognize emotions in photographs of facial expressions (Allerdings, 1997; Lane et al., 1996, 2000; Mann, Wise, Trinidad, & Kohanski, 1994; McDonald & Prkachin, 1990; Pandey & Mandal, 1997; Parker et al., 1993; Parker, Prkachin, & Prkachin, 2005; Prkachin, Casey, & Prkachin, 2009). These deficits have been found with tasks in which participants were required to reply in a very short period of time (Pedrosa et al., 2009), as well as in those with masked stimuli to make it difficult to recognize them (Kugel et al., 2008; Reker et al., 2010), and with static emotional stimuli, such as FACS, and dynamic videos (Katsyri, Saalasti, Tiippana, von Wendt, & Sams, 2008; Ridout, Thomas, & Wallis, 2010) (for a review, see Grynberg et al., 2012).Despite interest in studying relationship between alexithymia and emotion recognition, there are only a few studies addressing role of alexithymia in facial recognition tasks with parts of face, such as work of Swart, Kortekaas, and Aleman (2009) and Schimmenti (2016). …

Discriminating between first- and second-order cognition in first-episode paranoid schizophrenia

ABSTRACTIntroduction: An impairment of visually perceiving backward masked stimuli is commonly observed in patients with schizophrenia, yet it is unclear whether this impairment is the result of a deficiency in first or higher order processing and for which subtypes of schizophrenia it is present.Methods: Here, we compare identification (first order) and metacognitive (higher order) performance in a visual masking paradigm between a highly homogenous group of young first-episode patients diagnosed with paranoid schizophrenia (N = 11) to that of carefully matched healthy controls (N = 13).Results: We find no difference across groups in first-order performance, but find a difference in metacognitive performance, particularly for stimuli with relatively high visibility.Conclusions: These results indicate that the masking deficit is present in first-episode patients with paranoid schizophrenia, but that it is primarily an impairment of metacognition.

Unconscious processing of invisible visual stimuli.

Unconscious processing of subliminal visual information, as illustrated by the above-chance accuracy in discriminating invisible visual stimuli, is evident in both blindsight patients and healthy human observers. However, the dependence of such unconscious processing on stimulus properties remains unclear. Here we studied the impact of stimulus luminance and stimulus complexity on the extent of unconscious processing. A testing stimulus presented to one eye was rendered invisible by a masking stimulus presented to the other eye, and healthy human participants made a forced-choice discrimination of the stimulus identity followed by a report of the perceptual awareness. Without awareness of the stimulus existence, participants could nevertheless reach above-chance accuracy in discriminating the stimulus identity. Importantly, the discrimination accuracy for invisible stimuli increased with the stimulus luminance and decreased with the stimulus complexity. These findings suggested that the input signal strength and the input signal complexity can affect the extent of unconscious processing without altering the subjective awareness.

Visual mismatch negativity to masked stimuli presented at very brief presentation rates

Mismatch negativity (MMN) has been characterised as a ‘pre-attentive’ component of an event-related potential (ERP) that is related to discrimination and error prediction processes. The aim of the current experiment was to establish whether visual MMN could be recorded to briefly presented, backward and forward masked visual stimuli, given both below and above levels of subjective experience. Evidence of visual MMN elicitation in the absence of the ability to consciously report stimuli would provide strong evidence for the automaticity of the visual MMN mechanism. Using an oddball paradigm, two stimuli that differed in orientation from each other, a + and an ×, were presented on a computer screen. Electroencephalogram (EEG) was recorded from nine participants (six females), mean age 21.4 years. Results showed that for stimuli that were effectively masked at 7 ms presentation, there was little variation in the ERPs evoked to standard and deviant stimuli or in the subtraction waveform employed to delineate the visual MMN. At 14 ms stimulus presentation, when participants were able to report stimulus presence, an enhanced negativity at around 175 and 305 ms was observed to the deviant and was evident in the subtraction waveform. However, some of the difference observed in the ERPs can be attributed to stimulus characteristics, as the use of a ‘lonely’ deviant protocol revealed attenuated visual MMN components at 14 ms stimulus presentation. Overall, results suggest that some degree of conscious attention is required before visual MMN components emerge, suggesting visual MMN is not an entirely pre-attentive process.

The temporal frequency tuning of continuous flash suppression reveals peak suppression at very low frequencies.

Continuous flash suppression (CFS) is a psychophysical technique where a rapidly changing Mondrian pattern viewed by one eye suppresses the target in the other eye for several seconds. Despite the widespread use of CFS to study unconscious visual processes, the temporal tuning of CFS suppression is currently unknown. In the present study we used spatiotemporally filtered dynamic noise as masking stimuli to probe the temporal characteristics of CFS. Surprisingly, we find that suppression in CFS peaks very prominently at approximately 1 Hz, well below the rates typically used in CFS studies (10 Hz or more). As well as a strong bias to low temporal frequencies, CFS suppression is greater for high spatial frequencies and increases with increasing masker contrast, indicating involvement of parvocellular/ventral mechanisms in the suppression process. These results are reminiscent of binocular rivalry, and unifies two phenomenon previously thought to require different explanations.

Conscious and unconscious performance monitoring: Evidence from patients with schizophrenia

The ability to detect our own errors is an essential component of action monitoring. Using a masking paradigm in normal adults, we recently discovered that some error-detection processes can proceed without awareness, while other markers of performance monitoring such as the Error-Related Negativity (ERN) are tightly linked to conscious perception. Interestingly, research on cognitive deficit in schizophrenia has shown that the ERN is altered in these patients. In the present study, we therefore tested if the error detection impairment in schizophrenia is specific to conscious perception or is also found under non-conscious conditions, probing whether these performance monitoring processes are truly distinct. Thirteen patients with schizophrenia and thirteen age-matched healthy control subjects performed a speeded number comparison task on masked stimuli while EEG and MEG signals were recorded. Conscious perception and error-detection were assessed on a trial-by-trial basis using subjective reports of visibility and confidence. We found that patients with schizophrenia presented altered cingulate error-detection responses in conscious trials, as reflected by a decreased ERN. By contrast, on unconscious trials, both controls and schizophrenia patients performed above chance in evaluating the likelihood of having made an error. This dissociation confirms the existence of two distinct performance monitoring systems, and suggests that conscious metacognition in schizophrenia is specifically altered while non-conscious performance monitoring remains preserved.

Use of backward masking test for the study of visual information processing in healthy subjects and schizophrenic patients

The study of 14 healthy subjects and 15 schizophrenic patients was conducted under visual backward masking conditions. Sensory thresholds were identified using the method of constant stimuli. A special modification of the backward masking technique with lateralized presentation of test and masking stimuli was used to study the lateral characteristics of visual attention. It was found that the thresholds of letter stimulus identification were significantly higher in patients with schizophrenia than in healthy subjects. Only in patients the asymmetry of visual perception was revealed with the higher recognition thresholds in the left visual hemifield. The overall data analysis suggests an association between increased recognition thresholds in schizophrenic patients and changes in the interruption mechanism functioning at the neocortex level.

Constructing representations of spatial location from briefly presented displays.

Spatial memory and reasoning rely heavily on allocentric (often map-like) representations of spatial knowledge. While research has documented many ways in which spatial information can be represented in allocentric form, less is known about how such representations are constructed. For example: Are the very early, pre-attentive parts of the process hard-wired, or can they be altered by experience? We addressed this issue by presenting sub-saccadic (53ms) masked stimuli consisting of a target among one to three reference features. We then shifted the location of the feature array, and asked participants to identify the target's new relative location. Experience altered feature processing even when the display duration was too short to allow attention re-allocation. The results demonstrate the importance of early perceptual processes in the creation of representations of spatial location, and the malleability of those processes based on experience and expectations.

The functional role of time compression.

Multisensory integration provides continuous and stable perception from separate sensory inputs. Here, we investigated the functional role of temporal binding between the visual and the tactile senses. To this end we used the paradigm of compression that induces shifts in time when probe stimuli are degraded, e.g., by a visual mask (Zimmermann et al. 2014). Subjects had to estimate the duration of temporal intervals of 500 ms defined by a tactile and a visual, masked stimulus. We observed a strong (~100 ms) underestimation of the temporal interval when the stimuli from both senses appeared to occur at the same position in space. In contrast, when the positions of the visual and tactile stimuli were spatially separate, interval perception was almost veridical. Temporal compression furthermore depended on the correspondence of probe features and was absent when the orientation of the tactile and visual probes was incongruent. An additional experiment revealed that temporal compression also occurs when objects were presented outside the attentional focus. In conclusion, these data support a role for spatiotemporal binding in temporal compression, which is at least in part selective for object features.

제주 연안에서 양식된 참조기의 청각 능력

The purpose of this paper is to improve the availability of underwater sound by the fundamental data on the hearing ability of Redlip croaker Pseudosciaena polyactis, which is cultured according to the cultivation technology, recently. The auditory thresholds of Redlip croaker were determined at 6 frequencies from 80Hz to 800Hz by heartbeat conditioning method using pure tones coupled with a delayed electric shock. The audible range of the Redlip croaker extended from 80Hz to 800Hz with the best sensitive frequency range including little difference in hearing ability from 80Hz to 500Hz. In addition, the auditory thresholds over 800Hz increased rapidly. The mean auditory thresholds of the Redlip croaker at the test frequencies from 80Hz to 800Hz were 90.7dB, 93.4dB, 92.9dB, 94.4dB, 95.5dB and 108dB, respectively. Auditory masking for the redlip croaker was measured using masking stimuli with the spectrum level range of about 66, 71, 75dB (0dB re <TEX>$1{\mu}Pa/{\sqrt{Hz}}$</TEX>). According to white noise level, the auditory thresholds increased as compared with thresholds in a quiet background noise. The Auditory masking by the white noise spectrum level was stared over about 70dB within 80~500Hz. Critical ratio ranged from minimum 20.7dB to maximum 25.5dB at test frequencies of 80Hz~500Hz.

Forward masking in the superior paraolivary nucleus of the rat.

In natural acoustic environments, perception of acoustic stimuli depends on the recent contextual history. Forward masking describes a phenomenon whereby the detection threshold of a probe stimulus is markedly increased when it is preceded by a masking stimulus. The aim of this study was to characterize the offset response of single units in the superior paraolivary nucleus (SPON) to a forward masking paradigm. We observed two distinct response types to forward-masked stimuli, namely inhibited and facilitated responses. In the presence of a default masking stimulus, inhibited responses to probe stimuli were characterized by elevated thresholds and/or diminished spike counts, whereas facilitated responses were characterized by reduced thresholds and increased spike counts. In units with inhibited responses to the probe stimuli, probe thresholds increased and spike counts decreased as masker intensity was raised or the masker-to-probe delay was shortened. Conversely, in units with facilitated responses to the probe stimuli, probe thresholds decreased and spike counts increased as masker intensity was raised or the masker-to-probe delay was shortened. Neither inhibited nor facilitated responses to the forward masking paradigm were significantly dependent on masker frequency. These findings suggest that SPON responses are not themselves consistently subject to the same forward masking properties observed in other nuclei along the ascending auditory pathway. The potential neural mechanisms of the forward masking responses observed in the SPON are discussed.

Effects of various acoustic stimuli on higher order thinking and tinnitus perceptions

Masking sounds are often employed in the management of subjective tinnitus to desensitize and divert attention. The potential side effects of these maskers in distraction from other thought processes is not well understood. This research addresses the effects an artificial tinnitus and broadband masking or distracting stimuli have on performance of challenging cognitive or attention tasks. Masking sound preferences were also assessed. Adults with normal hearing and without thought processing disorders performed a two-back (n-back) auditory memory task in listening conditions including silence, white noise, classical music, pop music, and an artificial tinnitus condition. Participants also completed a survey, rating perceptions of their performance and attentional preferences for the sounds. Data show a greater distraction effect for more complex stimuli (pop music). Natural environmental sounds or white noise are favored to pop music for tinnitus masking. It is suggested that tinnitus maskers with more co...

Psychophysiological responses to listening to speech in intermittent noise

Listening to speech in noise can be effortful, and the presence of background noise may in itself provoke physiologically measurable stress. Typical laboratory tests of speech perception in noise often present masked stimuli in trials separated by silence, in effect starting and stopping an otherwise constant background noise multiple times over the course of an experiment. While these interruptions might reduce listener stress by providing momentary respite from an aversive stimulus, intermittent noise might also increase stress by repeatedly inducing automatic physiological responses to the noise onsets. Here, I present the results of an experiment contrasting these possibilities. Younger (age 18–36) and older (age 60 + ) listeners heard sentences presented in speech-shaped noise at 0 dB SNR while physiological responses linked to stress and arousal (skin conductance, heart rate, fingertip pulse amplitude, and facial electromyography) were recorded. Two roughly 15-min blocks of noise, each containing 36...

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&lt;p&gt;The article describes an experiment which used a new methodological approach to the study of covert recognition of faces by means of registration electro-dermal activity under short-term exposure of familiar and unfamiliar faces and the backward facelike masking stimulus. In contrast to previous studies the control of stimulus awareness allows us to evaluate not just the correct recognitions, but false alarms too. We used as the familiar faces not faces of the well-known persons, but faces of persons from the inner circle of subjects, including the subject&amp;rsquo;s own face. We confirmed the hypothesis that the characteristics of the electro-dermal reactions in response to familiar and unfamiliar faces will not be different in subjects with a high level of false alarms. However, for the group of subjects with practically zero false alarm rate and zero discriminability of familiar and unfamiliar faces an analysis of electro-dermal reactions have been mixed. On the one hand, as analysis on a group level showed, nor electrocutaneous reactions frequency, nor their amplitudes were not significantly different for the familiar and unfamiliar faces. On the other hand, it is clearly that these individual median and mean values of the amplitudes of subject's reactions are in average more than 2 times stronger when viewed familiar faces than viewed unfamiliar ones. These results leave a good chance to prove the effect of covert identification of faces in further experimentation with other groups of subjects&lt;/p&gt;

Differential effects of forward and backward masks on the relationship between perception and action.

A recent series of experiments has shown that the effects of near-threshold stimuli on perceptual and motor responses are highly dependent on experimental conditions. In particular, motor influences of near-threshold distractors were observed when using low-contrast unmasked stimuli and high-contrast masked stimuli although only the latter affected motor responses in the absence of stimulus awareness. These results are compatible with neurophysiological models of visual masking, suggesting that early neural responses to a visual stimulus can be decomposed in feedforward activations to-and feedback activations from-higher visual areas, correlating respectively with the actual presence of the stimulus and its conscious perception. We tested the compatibility between these neurophysiological models and the behavioural data obtained in near-threshold experiments. We recorded fast reaching movements directed to a highly visible target followed by a report of the presence of a near-threshold distractor presented either at low contrast without mask or at high contrast with a backward or forward mask. Analysis of hand trajectories revealed that deviations toward the distractor were observed in the no-mask condition when the distractor was present and reported, and when it was present but not reported in the backward and forward mask conditions, although the effect was weaker in the latter condition. These data reveal that the presence or absence of perception-action dissociations in behavioural studies are well accounted for by neurophysiological models of visual masking and that behavioural effects of near-threshold distractors cannot result merely from on a dichotomic visual system for perception and action.

Raising a racket: invasive species compete acoustically with native treefrogs

Environmental noise is increasing worldwide, limiting the space available for species to send and receive important acoustic information. Many invasive species produce acoustic signals that alter the spectrotemporal characteristics of available signalling space. This provides an opportunity to test ideas about competitive exclusion by quantifying whether species with shared requirements for acoustic resources will become excluded or partition resource use to permit coexistence. We conducted a field playback experiment to test whether native treefrogs (green treefrogs, Hyla cinerea; pine woods treefrogs, Hyla femoralis) modify their acoustic behaviour to minimize acoustic competition from chorus noise of the invasive Cuban treefrog, Osteopilus septentrionalis. We demonstrate that noise from an invasive species differentially affects the vocal behaviour of native species. Those with similar calls (H. cinerea) shortened calls, called louder and persisted calling in response to masking stimuli while those with different calls (H. femoralis) did not modify behaviour. This evidence suggests that acoustic competition by invasive O. septentrionalis has altered the acoustic community structure, identifying acoustic competition as a mechanism by which invasive species can impact communities. Furthermore, these results broaden the concept of noise pollution, demonstrating fitness-relevant consequences of noise produced by invasive species.