Hz Tone Research Articles

Effects of age, gender, and anthropometric measurements on simple visual and auditory reaction time in healthy Indian adults

Background: Reaction time (RT) is the time interval between the application of a stimulus and voluntary motor response. Both visual and auditory RT reflect the cognitive function of an individual specially in spatial skills. Aims and Objective: This study aims to find the correlation between age, gender, and anthropometric measurements on simple visual and auditory RT. Material and Methods: One hundred healthy volunteers of both the genders (males 52 and females 48) aged between 18 and 50 years were recruited. RT is the elapsed time between the presentation of a stimulus and the subsequent behavioral response to occur. Subjects were presented with red light and 1000 Hz tone sound stimuli for both the genders. In RT there is coordination between the sensory and motor system occurs. The height, weight, waist circumference, and waist–hip ratio (WHR) were measured to observe the effects of these measurements on visual reaction time (VRT) and auditory reaction time (ART). Results: Statistical analysis of the data by one-way ANOVA with post hoc by Turkey HSD test was found significant with age, gender, and other anthropometric measurements WHR, BSA, and waist circumference) with P-value of 0.027, 0.067; 0.001, 0.125 and BMI 0.135 and 0.200; WHR 0.086 and 0.043; 0.050 and 0.064, respectively. Conclusion: As hypothesis suggests when BMI is increased, there is a significant increase in RT. The VRT and ART both are increased in female than male. RT increases as the age increases especially after 40 years. Objective: The objective of the study was to find the correlation between age, gender, and anthropometric measurements on simple visual and auditory RT.

Simultaneous Intra- and Extracochlear Electrocochleography During Cochlear Implantation to Enhance Response Interpretation.

The use of electrocochleography (ECochG) for providing real-time feedback of cochlear function during cochlear implantation is receiving increased attention for preventing cochlear trauma and preserving residual hearing. Although various studies investigated the relationship between intra-operative ECochG measurements and surgical outcomes in recent years, the limited interpretability of ECochG response changes leads to conflicting study results and prevents the adoption of this method for clinical use. Specifically, the movement of the recording electrode with respect to the different signal generators in intracochlear recordings makes the interpretation of signal changes with respect to cochlear trauma difficult. Here, we demonstrate that comparison of ECochG signals recorded simultaneously from intracochlear locations and from a fixed extracochlear location can potentially allow a differentiation between traumatic and atraumatic signal changes in intracochlear recordings. We measured ECochG responses to 500 Hz tone bursts with alternating starting phases during cochlear implant insertions in six human cochlear implant recipients. Our results show that an amplitude decrease with associated near 180° phase shift and harmonic distortions in the intracochlear difference curve during the first half of insertion was not accompanied by a decrease in the extracochlear difference curve’s amplitude (n = 1), while late amplitude decreases in intracochlear difference curves (near full insertion, n = 2) did correspond to extracochlear amplitude decreases. These findings suggest a role for phase shifts, harmonic distortions, and recording location in interpreting intracochlear ECochG responses.

Tone detection thresholds in interaurally delayed noise of different bandwidths

Differences between the interaural phase of a noise and a target tone improve detection thresholds. The maximum masking release is obtained for detecting an antiphasic tone (Sπ) in diotic noise (N0). It has been shown in several studies that this benefit gradually declines as an interaural time delay (ITD) is applied to the noise. This decline has been attributed to the reduced interaural coherence of the noise. Here, we report detection thresholds for a 500 Hz tone in masking noise with ITDs up to 8 ms and bandwidths from 25 to 1000 Hz. Reducing the noise bandwidth from 100 to 50 and 25 Hz increased the masking release for 8-ms ITD, as expected for increasing temporal coherence with decreasing bandwidth. For bandwidths of 100–1000 Hz no significant difference in masking release was observed. Detection thresholds with these wider-band noises had an ITD dependence that is fully described by the temporal coherence imposed by the typical monaurally determined auditory-filter bandwidth. A binaural model based on interaural phase-difference fluctuations accounts for the data without using delay lines.

Envelope Following Response to 440 Hz Carrier Chirp-Modulated Tones Show Clinically Relevant Changes in Schizophrenia.

The 40 Hz auditory steady-state response (ASSR) impairment is suggested as an electrophysiological biomarker of schizophrenia; however, existing data also points to the deficiency of low and high frequency ASSR responses. In order to obtain the full picture of potential impairment in schizophrenia, it is important to test responses at different frequencies. The current study aims to evaluate a wide frequency range (1–120 Hz) in response to brief low-frequency carrier chirp-modulated tones in a group of patients with schizophrenia. The EEG-derived envelope following responses (EFRs) were obtained in a group of male patients with schizophrenia (N = 18) and matched controls (N = 18). While subjects were watching silent movies, 440 Hz carrier chirp-modulated at 1–120 Hz tones were presented. Phase-locking index and evoked amplitude in response to stimulation were assessed and compared on point-to-point basis. The peak frequency of the low gamma response was estimated. Measures were correlated with psychopathology—positive, negative, total scores of the Positive and Negative Syndrome Scale (PANSS), and hallucination subscale scores. In comparison to controls, patients showed (1) reduced power of theta-beta (4–18 Hz) responses, (2) intact but slower low gamma (30–60 Hz), and (3) reduced high gamma (95–120 Hz) responses. No correlation survived the Bonferroni correction, but a sign of positive association between low gamma phase-locking and the prevalence of hallucinations, and a sign of negative association between high gamma phase-locking and the total PANSS scores were observed. Brain networks showed impaired capabilities to generate EFRs at different frequencies in schizophrenia; moreover, even when responses of patients did not significantly differ from controls on the group level, they still showed potentially clinically relevant variability.

Investigation of Embodied Language Processing on Command-Swallow Performance in Healthy Participants.

Purpose During videofluoroscopic examination of swallowing, patients commonly are instructed to hold a bolus in their mouth until they hear a verbal instruction to swallow, which usually consists of the word swallow and is commonly referred to as the command swallow condition. The language-induced motor facilitation theory suggests that linguistic processes associated with the verbal command to swallow should facilitate the voluntary component of swallowing. As such, the purpose of the study was to examine the linguistic influences of the verbal command on swallowing. Method Twenty healthy young adult participants held a 5-ml liquid bolus in their mouth and swallowed the bolus after hearing one of five acoustic stimuli presented randomly: congruent action word (swallow), incongruent action word (cough), congruent pseudoword (spallow), incongruent pseudoword (pough), and nonverbal stimulus (1000-Hz pure tone). Suprahyoid muscle activity during swallowing was measured via surface electromyography (sEMG). Results The onset and peak sEMG latencies following the congruent action word swallow were shorter than latencies following the pure tone and pseudowords but were not different from the incongruent action word. The lack of difference between swallow and cough did not negate the positive impact of real words on timing. In contrast to expectations, sEMG activity duration and rise time were longer following the word swallow than the pure tone and pseudowords but were not different from cough. No differences were observed for peak suprahyoid muscle activity amplitude and fall times. Conclusions Language facilitation was observed in swallowing. The clinical utility of the information obtained in the study may depend on the purposes for using the command swallow and the type of patient being assessed. However, linguistic processing under the command swallow condition may alter swallow behaviors and suggests that linguistic inducement could be useful as a compensatory technique for patients with difficulty initiating oropharyngeal swallows.

A Preliminary Analysis of Hearing Loss and Its Association With Mild Cognitive Impairment

Age related hearing loss, or presbycusis, is a global condition that is increasing in its prevalence. Despite being one of the most common chronic conditions among the older population, there is much more to understand about its association with other aspects of physical and emotional health and well-being. Current research is suggesting that hearing loss is more prevalent in those with cognitive impairment compared to those without cognitive impairment. This study analyzed the incidence of hearing loss and its linkage to mild cognitive impairment in a community-dwelling geriatric population. With the increasing prevalence of this condition in both rural and urban communities of Alabama, it becomes a more pressing matter to understand comorbidities and risk factors for future decline in functioning. This study was conducted in an interdisciplinary geriatrics primary care outpatient clinic in a Family, Internal, and Rural Medicine department affiliated with a university medical center in the Deep South. Ninety-one participants completed the Montreal Cognitive Assessment (MoCA) and a hearing screening. Hearing screenings were conducted in quiet rooms in the medical center using Phonak hearing screening cards. Detection of 500, 1000, 2000, and 4000 Hz tones was assessed. Pearson correlation analyses demonstrated an association between hearing loss mild cognitive impairment. Poorer hearing was significantly associated with lower scores on the MoCA. Conducting behavioral health screenings like this in other primary geriatrics clinics and community settings could improve care and identification of patient needs by integrating important data regarding comorbidities and independent living.

Differences in bone conduction ocular vestibular evoked myogenic potentials to 500 Hz narrow band chirp stimulus and 500 Hz tone burst

ObjectiveThis study aims to investigate the differences of N1 latency, P1 latency and N1P1 amplitude in response to bone conducted 500 Hz tone burst and narrowband CE chirp stimulus in ocular vestibular evoked myogenic potentials (oVEMPs). MethodsForty-two healthy volunteers were included in this prospective study. Subjects with abnormal otological examinations and otological diseases were excluded. oVEMPs were randomly recorded in response to BC 500 Hz narrowband (NB) chirp stimulus and BC 500 Hz tone burst. The stimulus intensity was 50 dB nHL for both 500 Hz tone burst and 500 Hz NB CE chirp stimulus. P1 latency, N1 latency, and N1P1 amplitude were measured, and these measurements were compared between these two types of stimuli. ResultsBoth types of stimuli elicited oVEMP in all subjects. N1 latency and P1 latency were significantly shorter (6.41 ms vs 10.84 ms; 10.64 ms vs 15.56 ms, respectively) for chirp stimulus (p < 0.05). N1P1 amplitude was significantly higher (11.64 vs 7.18 μV) for NB chirp stimulus (p < 0.05). ConclusionIt is reasonable to conclude that the NB CE chirp stimulus is effective to elicit robust BC oVEMP in healthy subjects.

Binaural Frequency Modulation Detection in School-Age Children, Young Adults, and Older Adults: Effects of Interaural Modulator Phase.

The purpose of this study was to measure low-rate binaural frequency modulation (FM) detection across the lifespan as a gauge of temporal fine structure processing. Children and older adults were expected to perform more poorly than young adults but for different reasons. Detection of 2-Hz FM carried by a 500-Hz pure tone was measured for modulators that were either in-phase or out-of-phase across ears. Thresholds were measured in quiet and in noise. Participants were school-age children (n = 44), young adults (n = 11), and older adults (n = 17) with normal or near-normal hearing. Thresholds were lower for out-of-phase than in-phase modulators among all listening groups. Detection thresholds improved with child age, with larger effects of age for dichotic than diotic FM. Introduction of masking noise tended to elevate thresholds; this effect was larger for the dichotic condition than the diotic condition, and larger for older adults than young adults. In noise, young adults received the greatest dichotic benefit, followed by older adults, then young children. The relative effects of noise on dichotic benefit did not differ for young adults compared to young children and older adults; however, young children saw greater reduction in benefit due to noise than older adults. The difference in dichotic benefit between children and young adults is consistent with maturation of central auditory processing. Differences in the effect of noise on dichotic benefit in young children and older adults support the idea that different factors or combinations of factors limit performance in these two groups. Although dichotic FM detection appears to be more sensitive to the effects of development and aging than diotic FM detection, the positive correlation between diotic and dichotic FM detection thresholds for all listeners suggests contribution of one or more factors common to both conditions.

Visual load effects on the auditory steady-state responses to 20-, 40-, and 80-Hz amplitude-modulated tones

Ignoring background sounds while focusing on a visual task is a necessary ability in everyday life. If attentional resources are shared between modalities, processing of task-irrelevant auditory information should become attenuated when attentional capacity is expended by visual demands. According to the early-filter model, top-down attenuation of auditory responses is possible at various stages of the auditory pathway through multiple recurrent loops. Furthermore, the adaptive filtering model of selective attention suggests that filtering occurs early when concurrent visual tasks are demanding (e.g., high load) and late when tasks are easy (e.g., low load). To test these models, this study examined the effects of three levels of visual load on auditory steady-state responses (ASSRs) at three modulation frequencies. Subjects performed a visual task with no, low, and high visual load while ignoring task-irrelevant sounds. The auditory stimuli were 500-Hz tones amplitude-modulated at 20, 40, or 80 Hz to target different processing stages of the auditory pathway. Results from bayesian analyses suggest that ASSRs are unaffected by visual load. These findings imply that attentional resources are modality specific and that the attentional filter of auditory processing does not vary with visual task demands.

Cortical processing of location and frequency changes of sounds in normal hearing listeners

Sounds we hear in our daily life contain changes in the acoustic features (e.g., frequency, intensity, and duration or “what” information) and/or changes in location (“where” information). The purpose of this study was to examine the cortical auditory evoked potentials (CAEPs) to the change within a stimulus, the acoustic change complex (ACC), in frequency (F) and location (L) of the sound in normal hearing listeners.Fifteen right-handed young normal hearing listeners participated in the electroencephalographic (EEG) recordings. The acoustic stimuli were pure tones (base frequency at 250 Hz) of 1 s, with a perceivable change either in location (L, 180°), frequency (F, 5% and 50%), or both location and frequency (L+F) in the middle of the tone. Additionally, the 250 Hz tone of 1 sec without any change was used as a reference. The participants were asked to listen passively to the stimuli and not to move their heads during the testing. Compared to the reference tone, by which only the onset-CAEP was elicited, the tones containing changes (L, F, or L+F) elicited both onset-CAEP and the ACC. The waveform analysis of ACCs from the vertex electrode (electrode Cz) showed that, larger sound changes evoked larger peak amplitudes [e.g., (L+50%F)- > L-change; (L+50%F)- > 5%F-change] and shorter the peak latencies ([(L+5%F)- < 5%F-change; 50%F- < 5%F-change; (L+50%F)- < 5%F-change] . The current density patterns for the ACC N1’ peak displayed some differences between L-change vs. F-change, supporting different cortical processing for “where” and “what” information of the sound; regardless of the nature of the sound change, larger changes evoked a stronger activation than smaller changes [e.g., L- > 5%F-change; (L+5%F)- > 5%F-change; 50%F- > 5%F-change] in frontal lobe regions including the cingulate gyrus, medial frontal gyrus (MFG), superior frontal gyrus (SFG), the limbic lobe cingulate gyrus, and the parietal lobe postcentral gyrus. The results suggested that sound change-detection involves memory-based acoustic comparison (the neural encoding for the sound change vs. neural encoding for the pre-change stimulus stored in memory) and involuntary attention switch.

Reduced multisensory facilitation exists at different periods of development in autism

Atypical sensory processing is now recognised as a key component of an autism diagnosis. The integration of multiple sensory inputs (multisensory integration (MSI)) is thought to be idiosyncratic in autistic individuals and may have cascading effects on the development of higher-level skills such as social communication.Multisensory facilitation was assessed using a target detection paradigm in 45 autistic and 111 neurotypical individuals, matched on age and IQ. Target stimuli were: auditory (A; 3500 Hz tone), visual (V; white disk ‘flash’) or audiovisual (AV; simultaneous tone and flash), and were presented on a dark background in a randomized order with varying stimulus onset delays. Reaction time (RT) was recorded via button press. In order to assess possible developmental effects, participants were divided into younger (age 14 or younger) and older (age 15 and older) groups.Redundancy gain (RG) was significantly greater in neurotypical, compared to autistic individuals. No significant effect of age or interaction was found. Race model analysis was used to compute a bound value that represented the facilitation effect provided by MSI. Our results revealed that MSI facilitation occurred (violation of the race model) in neurotypical individuals, with more efficient MSI in older participants. In both the younger and older autistic groups, we found reduced MSI facilitation (no or limited violation of the race model).Autistic participants showed reduced multisensory facilitation compared to neurotypical participants in a simple target detection task, void of social context. This remained consistent across age. Our results support evidence that autistic individuals may not integrate low-level, non-social information in a typical fashion, adding to the growing discussion around the influential effect that basic perceptual atypicalities may have on the development of higher-level, core aspects of autism.

The clinical utility of the cervical vestibular-evoked myogenic potential (cVEMP) in university-level athletes with concussion

Concussion is defined as a mild traumatic brain injury that can occur in all sport activities. Cervical vestibular-evoked myogenic potentials (cVEMPs) are accepted to demonstrate the vestibulocollic reflex. MAIN: To evaluate subclinical cervical abnormalities in the vestibulospinal pathway in subjects with concussion history with and without related symptoms via evoked vestibular potential. Monaurally air conduction cVEMP (500 Hz tone bursts) at intensity of 100 dBnHL and 200 sweeps. All responses were replicated. One hundred fifty-four participants were initially tested; however, three (03) participants did not produce usable data (no response) and were eliminated for the dataset cutoff values analysis, being considered just as abnormal response. One hundred fifty-one responses consisted of 45 non-athlete individuals without any history of a concussion or concussion symptoms (normative group), 45 athletes without any history of a concussion or concussion symptoms (control group), 33 athletes with a history of at least one concussion but no concussion symptoms related (history group), and 28 athletes with a history of at least one concussion and concussion symptoms (symptoms group). The history and symptoms groups had statistically higher latency scores than the control and the normative groups. The Index Ratio data and Threshold data did not produce a significant effect for four groups. But, a pattern of abnormal cVEMP was found when comparing those without a history of concussion (0% abnormal response) versus the history group (24%) and symptoms group (32.3%). The study provides data which supports the positive impact of cVEMP when evaluating athletes and identifying concussion processes.

Association of cervical vestibular-evoked myogenic potential tuning property test results with MRI findings of endolymphatic hydrops in Meniere's disease.

To examine the concordance between cervical vestibular-evoked myogenic potential (cVEMP) tuning property test results and MRI findings of endolymphatic hydrops (EH). Fourteen subjects (age 24-76years) that had been diagnosed with unilateral definite Meniere's disease (MD) (N = 8) or unilateral probable MD (N = 6) were enrolled. All of the subjects underwent cVEMP tests (using 500Hz and 1000Hz tone bursts), pure-tone audiometry, and gadolinium-enhanced 3T-MRI. To examine tuning properties of cVEMP, the 500-1000Hz amplitude ratio was calculated as the SLOPE. The results of the cVEMP tuning property test results were compared with EH-related MRI findings. EH positivity in both the cochlea and vestibule on MRI was observed in 7 of the 8 affected ears of definite MD and 3 of the 6 affected ears of probable MD, although it was only in one of the 14 unaffected ears. EH(+) or no response (NR) in cVEMP tuning property test was significantly associated with EH positivity on MRI, while EH(-) in the cVEMP tuning property test was significantly associated with EH-negativity on MRI (p = 0.0016 Fisher's exact test test). EH(+) or NR in the cVEMP tuning property test correspond well to EH positivity in the MRI findings. The cVEMP tuning property test is useful for screening and following up EH.

Auditory sensory gating in Huffaz using an auditory brainstem response with a psychological task: A preliminary investigation

ObjectiveThis study aims to investigate the auditory sensory gating capacity in Huffaz using an auditory brainstem response (ABR) test with and without psychological tasks. MethodsTwenty-three participants were recruited for this study. The participants were comprised of 11 Huffaz who memorized 30 chapters of the Islamic Scripture (from the Quran) and 12 non-Huffaz as the control group. All participants had normal hearing perception and underwent an ABR test with and without psychological tasks. The ABR was elicited at 70 dB nHL using a 3000 Hz tone burst stimulus with a 2-0-2 cycle at a stimulus repetition rate of 40 Hz. The ABR wave V amplitude and latencies were measured and statistically compared. A forward digit span test was also conducted to determine participants’ working memory capacity. ResultsThere were no significant differences in the ABR wave V amplitudes and latencies between Huffaz and non-Huffaz in ABR with and without psychological tasks. There were also no significant differences in the ABR wave V amplitudes and latencies in both groups of ABR with and without psychological tasks. In addition, no significant differences were identified in the digit span working memory score between both groups. ConclusionsIn this study, based on the ABR findings, Huffaz showed the same auditory sensory gating capacity as the non-Huffaz group. The ABR result was consistent with the digit span working memory test score. This finding implies that both groups have similar working memory performance. However, the conclusion is limited to the specific assessment method that we used in this study.

Visual load does not decrease the auditory steady-state response to 40-Hz amplitude-modulated tones.

The auditory pathway consists of multiple recurrent loops of afferent and efferent connections that extend from the cochlea up to the prefrontal cortex. The early‐filter theory proposes that these loops allow top‐down filtering of early and middle latency auditory responses. Furthermore, the adaptive filtering model suggests that the filtering of irrelevant auditory stimuli should start lower in the pathway during more demanding tasks. If so, the 40‐Hz auditory steady‐state responses (ASSRs) to irrelevant sounds should be affected by top‐down crossmodal attention to a visual task, and effects should vary with the load of the visual task. Because few studies have examined this possibility, we conducted two preregistered studies that manipulated visual load (Study 1: N = 43, Study 2: N = 45). Study 1 used two levels (low and high), and Study 2 used four levels (no, low, high, and very high). Subjects were asked to ignore a 500‐Hz task‐irrelevant tone that was amplitude‐modulated to evoke 40‐Hz ASSRs. Results from Bayesian analyses provided moderate to extreme support for no effect of load (or of a task) on ASSRs. Results also supported no interaction with time (i.e., over blocks, over minutes, or with changes in ASSRs that were synchronized with the onset of the visual stimuli). Further, results provided moderate support for no correlation between the effects of load and working memory capacity. Because the present findings support the robustness of ASSRs against manipulations of crossmodal attention, they are not consistent with the adaptive filtering model.

Simultaneous Intra- and Extracochlear Electrocochleography During Electrode Insertion

(1) To correlate simultaneously recorded intra- and extracochlear electrocochleography (ECochG) signals during electrode insertion into the cochlea, (2) to track changes in the ECochG signal during insertion and removal of an electrode, and (3) to correlate the findings with the preoperative residual hearing. We hypothesized that intracochlear ECochG recordings show signal changes not reflected in simultaneous extracochlear ECochG recordings. During cochlear implantation in human cochlear implant recipients, a short, slim, custom-made electrode was inserted and removed in a stepwise manner. At each step, ECochG recordings were simultaneously recorded by an extracochlear electrode near the round window and via the inserted electrode. The acoustic stimulus was a 500 Hz tone burst at 110 to 130 dB SPL. The mean amplitude difference between intra- and extracochlear ongoing ECochG responses was 14 dB (range 9 to 24 dB; n = 10) at the beginning of insertion. Intracochlear ECochG responses were larger in all cases. Extracochlear ECochG responses remained stable while intracochlear recordings showed large variations regarding amplitude and phase during the electrode array insertion. Intracochlear signal changes during insertion were reversible with retraction of the electrode. There were only weak to moderate (rs = 0.006 to 0.4), nonsignificant correlations of residual preoperative hearing with maximum amplitudes and amplitude changes during electrode insertion and removal in intracochlear recordings. Signals in intracochlear ECochG recordings are reliably larger than ECochG signals recorded simultaneously from an extracochlear location. Intracochlear ECochG recordings show reversible amplitude and phase changes during insertion, not reflected in simultaneous extracochlear ECochG recordings. Such changes are most likely due to the movement of the recording electrode in relation to the signal generators. Residual high-frequency hearing is associated with larger ECochG signal amplitudes. Modeling of expected intracochlear ECochG changes during electrode insertions may allow detection of cochlear trauma in the future.

Effects of Tonic Muscle Activation on Amplitude-Modulated Cervical Vestibular Evoked Myogenic Potentials (AMcVEMPs) in Young Females: Preliminary Findings.

Cervical vestibular evoked myogenic potentials (cVEMPs) are usually elicited by transient tonebursts, but when elicited by amplitude-modulated (AM) tones, they can provide new information about cVEMPs. Previous reports of cVEMPs elicited by AM tones, or AMcVEMPs, have not systematically examined the effects of tonic EMG activation on their response properties. Fourteen young, healthy female adults (ages 20-24) with clinically normal audiograms participated in this study. AMcVEMPs were elicited with bone-conducted 500Hz tones amplitude modulated at a rate of 37Hz and recorded for five different EMG targets ranging from 0 to 90μV. Amplitude increased linearly as tonic EMG activation increased. Signal-to-noise ratio (SNR) was minimal at 0μV, but robust and with equivalent values from 30 to 90μV; phase coherence and EMG-corrected amplitude had findings similar to SNR across EMG target levels. Interaural asymmetry ratios for SNR and phase coherence were substantially lower than those for raw or corrected amplitude. AMcVEMP amplitude scaled with tonic EMG activation similar to transient cVEMPs. Signal-to-noise ratio, phase coherence, and EMG-corrected amplitude plateaued across a range of EMG values, suggesting that these properties of the response reach their maximum values at relatively low levels of EMG activation and that higher levels of EMG activation are not necessary to record robust AMcVEMPs.

Perceptual organization and stability of auditory streaming for pure tones and /ba/ stimuli

The dynamics of auditory stream segregation were evaluated using repeating triplets composed of pure tones or the syllable /ba/. Stimuli differed in frequency (tones) or fundamental frequency (speech) by 4, 6, 8, or 10 semitones, and the standard frequency was either 250 Hz (tones and speech) or 400 Hz (tones). Twenty normal-hearing adults participated. For both tones and speech, a two-stream percept became more likely as frequency separation increased. Perceptual organization for speech tended to be more integrated and less stable compared to tones. Results suggest that prior data patterns observed with tones in this paradigm may generalize to speech stimuli.

Puffin hearing unaffected by amphibious lifestyle

My diving is terrible – I can never clear my ears properly, even within 1 m of the surface – which makes the achievements of diving Atlantic puffins even more impressive, plummeting 150 m down with no apparent concern for their ears. ‘It is conceivable that the air-filled sinuses and auditory abilities are modified in auks, perhaps to withstand deep dives or enable underwater hearing’, says Aran Mooney, from the Woods Hole Oceanographic Institution, USA. Yet, it wasn't clear how the puffins’ amphibious lifestyle might impact their hearing out of water and whether they are distressed by noise. Mooney explains that other species are clearly disturbed by human noise, spending less time on the nest when people are around. Joining Ole Larsen and Kirstin Hansen, from the University of Southern Denmark, and Marianne Rasmussen, from the University of Iceland, Mooney and Adam Smith travelled to northern Iceland to collect puffins as they emerged from their burrows, to test their hearing.‘The burrows are often on high cliffs, so are a bit perilous to approach and work near, given the sheer drop and potential instability’, says Mooney, who eventually captured nine birds. After transporting them to an improvised lab in a nearby farm shed, the team gently sedated the animals and inserted fine electrodes beneath their skin before recording their responses to clicks ranging from low-pitched 125 Hz tones to 8 kHz beeps at a 20 dB whisper up to 100 dB to find out which frequencies the puffins were most sensitive to. Although the birds could hear sounds up to 6 kHz, their hearing was sharpest between 750 Hz and 3 kHz. And, when the team compared the birds’ hearing with that of other similarly sized birds, it seemed that their aquatic lifestyle has not affected their hearing at all: it's just as good as that of birds that never plunge beneath the waves. However, the team suspects that the windswept locations of the birds’ nesting sites with the noise of waves crashing below could limit their hearing above ground.The hearing of these charismatic birds is probably fine-tuned to the cries of their own chicks and other puffins. In addition, they are also less likely to be disturbed by their noisy surroundings when secluded in their burrows. However, Mooney believes that the thud of approaching human feet is likely to penetrate their otherwise peaceful homes. ‘Given the influence of human encroachment on bird colonies, the sensitive hearing of these animals and the fact that puffins are a major tourist attraction in many countries, we suggest that human disturbance noise, even low-level sounds from hikers and visitors, has the potential to disturb puffins’, he says.

Molecular and cellular responses to long-term sound exposure in peled (Coregonus peled).

This research examined the impacts of acoustic stress in peled (Coregonus peled Gmelin, 1788), a species commonly cultivated in Russia. This study presents a comparative analysis of the macula sacculi and otoliths, as well as primary hematological and secondary telomere stress responses, in control and sound-exposed peled. The authors measured the effects of long-term (up to 18 days) exposure to a 300 Hz tone at mean sound pressure levels of 176-186 dB re 1 μPa (SPLpk-pk); the frequency and intensity were selected to approximate loud acoustic environments associated with cleaning equipment in aquaculture settings. Acoustic exposure resulted in ultrastructure changes to otoliths, morphological damage to sensory hair cells of the macula sacculi, and a gradual decrease in the number of functionally active mitochondria in the red blood cells but no changes to telomeres. Changes were apparent following at least ten days of acoustic exposure. These data suggest that acoustic exposure found in some aquaculture settings could cause stress responses and auditory damage to peled and, potentially, other commercially important species. Reducing sound levels in fish rearing facilities could contribute to the formation of effective aquaculture practices that mitigate noise-induced stress in fishes.