Neural correlates of tonal loudness, intensity discrimination, and duration discrimination.

A long-standing quest in audition concerns understanding relations between behavioral measures and neural representations of changes in sound intensity. Here, we examined relations between aspects of intensity perception and central neural responses within the inferior colliculus of unanesthetized rabbits (by averaging the population's spike count/level functions). We found parallels between the population's neural output and: (1) how loudness grows with intensity; (2) how loudness grows with duration; (3) how discrimination of intensity improves with increasing sound level; (4) findings that intensity discrimination does not depend on duration; and (5) findings that duration discrimination is a constant fraction of base duration.

Perceptual Consequences of Cochlear Deafferentation in Humans.

Cochlear synaptopathy, a form of cochlear deafferentation, has been demonstrated in a number of animal species, including non-human primates. Both age and noise exposure contribute to synaptopathy in animal models, indicating that it may be a common type of auditory dysfunction in humans. Temporal bone and auditory physiological data suggest that age and occupational/military noise exposure also lead to synaptopathy in humans. The predicted perceptual consequences of synaptopathy include tinnitus, hyperacusis, and difficulty with speech-in-noise perception. However, confirming the perceptual impacts of this form of cochlear deafferentation presents a particular challenge because synaptopathy can only be confirmed through post-mortem temporal bone analysis and auditory perception is difficult to evaluate in animals. Animal data suggest that deafferentation leads to increased central gain, signs of tinnitus and abnormal loudness perception, and deficits in temporal processing and signal-in-noise detection. If equivalent changes occur in humans following deafferentation, this would be expected to increase the likelihood of developing tinnitus, hyperacusis, and difficulty with speech-in-noise perception. Physiological data from humans is consistent with the hypothesis that deafferentation is associated with increased central gain and a greater likelihood of tinnitus perception, while human data on the relationship between deafferentation and hyperacusis is extremely limited. Many human studies have investigated the relationship between physiological correlates of deafferentation and difficulty with speech-in-noise perception, with mixed findings. A non-linear relationship between deafferentation and speech perception may have contributed to the mixed results. When differences in sample characteristics and study measurements are considered, the findings may be more consistent.

The Accompanying Effect in Responses to Auditory Perturbations: Unconscious Vocal Adjustments to Unperturbed Parameters.

PURPOSE: The present study examined whether participants respond to unperturbed parameters while experiencing specific perturbations in auditory feedback. For instance, we aim to determine if speakers adjust voice loudness when only pitch is artificially altered in auditory feedback. This phenomenon is referred to as the "accompanying effect" in the present study. METHOD: Thirty native Mandarin speakers were asked to sustain the vowel /ɛ/ for 3 s while their auditory feedback underwent single shifts in one of the three distinct ways: pitch shift (±100 cents; coded as PT), loudness shift (±6 dB; coded as LD), or first formant (F1) shift (±100 Hz; coded as FM). Participants were instructed to ignore the perturbations in their auditory feedback. Response types were categorized based on pitch, loudness, and F1 for each individual trial, such as Popp_Lopp_Fopp indicating opposing responses in all three domains. RESULTS: The accompanying effect appeared 93% of the time. Bayesian Poisson regression models indicate that opposing responses in all three domains (Popp_Lopp_Fopp) were the most prevalent response type across the conditions (PT, LD, and FM). The more frequently used response types exhibited opposing responses and significantly larger response curves than the less frequently used response types. Following responses became more prevalent only when the perturbed stimuli were perceived as voices from someone else (external references), particularly in the FM condition. In terms of isotropy, loudness and F1 tended to change in the same direction rather than loudness and pitch. CONCLUSION: The presence of the accompanying effect suggests that the motor systems responsible for regulating pitch, loudness, and formants are not entirely independent but rather interconnected to some degree.

Background and Rationale for a Transitional Intervention for Debilitating Hyperacusis.

PURPOSE: This report provides the experimental, clinical, theoretical, and historical background that motivated a patented transitional intervention and its implementation and evaluation in a field trial for mitigation of debilitating loudness-based hyperacusis (LH). BACKGROUND AND RATIONALE: Barriers for ameliorating LH, which is differentiated here from other forms of hyperacusis, are delineated, including counterproductive management and treatment strategies that may exacerbate the condition. Evidence for hyper-gain central auditory processes as the bases for LH and the associated LH-induced distress and stress responses are presented. This presentation is followed by an overview of prior efforts to use counseling and therapeutic sound as interventional tools for recalibrating the hyper-gain LH response. We also consider previous efforts to use output-limiting sound-protection devices in the management of LH. This historical background lays the foundation for our transitional intervention protocol and its implementation and evaluation in a field trial. CONCLUSIONS: The successful implementation and evaluation of a transitional intervention, which we document in the outcomes of a companion proof-of-concept field trial in this issue, build on our prior efforts and those of others to understand, manage, and treat hyperacusis. These efforts to overcome significant barriers and vexing long-standing challenges in the management and treatment of LH, as reviewed here, are the pillars of the transitional intervention and its primary components, namely, counseling combined with protective sound management and therapeutic sound, which we detail in separate reports in this issue.

Device and Fitting Protocol for a Transitional Intervention for Debilitating Hyperacusis.

PURPOSE: This report describes a hearing device and corresponding fitting protocol designed for use in a transitional intervention for debilitating loudness-based hyperacusis. METHOD: The intervention goal is to transition patients with hyperacusis from their typical counterproductive sound avoidance behaviors (i.e., sound attenuation and limited exposure to healthy low-level sounds) into beneficial sound therapy treatment that can expand their dynamic range to the point where they can tolerate everyday sounds and experience an improved quality of life. This requires a combination of counseling and sound therapy, the latter of which is provided via the hearing device technology, signal processing, and precision fitting approach described in this report. The device combines a miniature behind-the-ear sound processor and a custom earpiece designed to maximize the attenuation of external sounds. Output-limiting loudness suppression is used to restrict exposure to offending high-level sounds while unity gain amplification maximizes exposure to healthy and tolerable lower level sounds. The fitting process includes measurement of the real-ear unaided response, the real-ear measurement (REM) system noise floor, the real-ear occluded response, real-ear insertion gain, and the output limit. With these measurements, the device can achieve the prescribed unity gain needed to provide transparent access to comfortable sound levels. It also supports individualized configuration of the therapeutic noise from an on-board sound generator and adaptive output limiting based on treatment-induced increases in dynamic range. RESULTS AND CONCLUSION: The utility of this device and fitting protocol, in combination with structured counseling, is highlighted in the outcomes of a successful 6-month trial of the transitional intervention described in a companion report in this issue.

The Association Between Tinnitus Sensation-Level Loudness and Sleep Quality in Patients With Subjective Consecutive Tinnitus: A Mediation Analysis.

PURPOSE: So far, there have been no in-depth analyses of the connection between tinnitus sensation-level loudness and sleep quality. Accordingly, the present study was formulated as a mediation analysis focused on exploring this relationship. METHOD: Overall, 1,255 adults with consecutive subjective tinnitus who had sought outpatient treatment were enrolled in the present study. RESULTS: Direct effects of tinnitus sensation-level loudness on sleep quality were not statistically significant (95% confidence intervals [CI] include zero), as measured by the point estimate, -0.016. However, the 95% CI for indirect effects did not include zero when assessing the Self-Rating Anxiety Scale (SAS) scores, the Self-Rating Depression Scale (SDS) scores, the visual analogue scale (VAS) scores, and self-reported tinnitus annoyance. CONCLUSIONS: These results suggest that tinnitus sensation-level loudness does not directly have an effect on sleep quality. However, it indirectly impacts sleep quality, mediated by SAS scores, SDS scores, the impact of tinnitus on life measured using the VAS, and self-reported tinnitus annoyance. As such, alleviating anxiety and depression in patients with tinnitus may result in reductions in their insomnia even if there is no reduction in tinnitus loudness. Importantly, otolaryngologists and other clinicians treating tinnitus should refer patients with tinnitus suffering from insomnia with comorbid depression or anxiety for appropriate psychological and/or psychiatric treatment.

Speeded classification of visual events is sensitive to crossmodal intensity correspondence.

Crossmodal correspondences refer to systematic associations between stimulus attributes encountered in different sensory modalities. These correspondences can be probed in the speeded classification task where they tend to produce congruency effects. This study aimed to replicate and extend previous work conducted by Marks (1987, Experiment 3, Journal of Experimental Psychology: Human Perception and Performance, Vol. 13, No. 3, 384-394) which demonstrated a crossmodal correspondence between auditory and visual intensity attributes. Experiment 1 successfully replicates Marks' original finding that performance in a brightness classification task is affected by whether the loudness of a concurrently presented auditory distractor matches the brightness of the visual target. Furthermore, in line with the original study, we found that this effect was absent in a lightness classification task. In Experiment 2, we demonstrate that loudness-brightness correspondence is robust even when the exact stimulus input changes. This finding suggests that there is a context-dependent mapping between loudness and brightness levels, rather than an absolute mapping between any particular intensity levels. Finally, exploratory analysis using the diffusion model for conflict tasks indicated that evidence from the task-irrelevant modality generates a burst of weak, short-lived automatic activation that can bias decision-making in difficult tasks, but not in easy tasks. Our results provide further evidence for the existence of a flexible crossmodal correspondence between brightness and loudness, which might be helpful in determining one's distance to a stimulus source during the early stages of multisensory integration. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Loudness Balancing Optimization for Better Speech Intelligibility, Music Perception, and Spectral Temporal Resolution in Cochlear Implant Users.

HYPOTHESIS: The behaviorally based programming with loudness balancing (LB) would result in better speech understanding, spectral-temporal resolution, and music perception scores, and there would be a relationship between these scores. BACKGROUND: Loudness imbalances at upper stimulation levels may cause sounds to be perceived as irregular, gravelly, or overly echoed and may negatively affect the listening performance of the cochlear implant (CI) user. LB should be performed after fitting to overcome these problems. METHODS: The study included 26 unilateral Med-EL CI users. Two different CI programs based on the objective electrically evoked stapedial reflex threshold (P1) and the behaviorally program with LB (P2) were recorded for each participant. The Turkish Matrix Sentence Test (TMS) was applied to evaluate speech perception; the Random Gap Detection Test (RGDT) and Spectral-Temporally Modulated Ripple Test (SMRT) were applied to evaluate spectral temporal resolution skills; the Mini Profile of Music Perception Skills (mini-PROMS) and Melodic Contour Identification (MCI) tests were applied to evaluate music perception, and the results were compared. RESULTS: Significantly better scores were obtained with P2 in TMS tests performed in noise and quiet. SMRT scores were significantly correlated with TMS in quiet and noise, and mini-PROMS sound perception results. Although better scores were obtained with P2 in the mini-PROMS total score and MCI, a significant difference was found only for MCI. CONCLUSION: The data from the current study showed that equalization of loudness across CI electrodes leads to better perceptual acuity. It also revealed the relationship between speech perception, spectral-temporal resolution, and music perception.

Comparing auditory distance perception in real and virtual environments and the role of the loudness cue: A study based on event-related potentials.

The perception of the distance to a sound source is relevant in many everyday situations, not only in real spaces, but also in virtual reality (VR) environments. Where real rooms often reach their limits, VR offers far-reaching possibilities to simulate a wide range of acoustic scenarios. However, in virtual room acoustics a plausible reproduction of distance-related cues can be challenging. In the present study, we compared the detection of changes of the distance to a sound source and its neurocognitive correlates in a real and a virtual reverberant environment, using an active auditory oddball paradigm and EEG measures. The main goal was to test whether the experiments in the virtual and real environments produced equivalent behavioral and EEG results. Three loudspeakers were placed at ego-centric distances of 2 m (near), 4 m (center), and 8 m (far) in front of the participants (N = 20), each 66 cm below their ear level. Sequences of 500 ms noise stimuli were presented either from the center position (standards, 80 % of trials) or from the near or far position (targets, 10 % each). The participants had to indicate a target position via a joystick response ("near" or "far"). Sounds were emitted either by real loudspeakers in the real environment or rendered and played back for the corresponding positions via headphones in the virtual environment. In addition, within both environments, loudness of the auditory stimuli was either unaltered (natural loudness) or the loudness cue was manipulated, so that all three loudspeakers were perceived equally loud at the listener's position (matched loudness). The EEG analysis focused on the mismatch negativity (MMN), P3a, and P3b as correlates of deviance detection, attentional orientation, and context-updating/stimulus evaluation, respectively. Overall, behavioral data showed that detection of the target positions was reduced within the virtual environment, and especially when loudness was matched. Except for slight latency shifts in the virtual environment, EEG analysis indicated comparable patterns within both environments and independent of loudness settings. Thus, while the neurocognitive processing of changes in distance appears to be similar in virtual and real spaces, a proper representation of loudness appears to be crucial to achieve a good task performance in virtual acoustic environments.

On the Effect of High Stimulation Rates on Temporal Loudness Integration in Cochlear Implant Users.

Long stimuli have lower detection thresholds or are perceived louder than short stimuli with the same intensity, an effect known as temporal loudness integration (TLI). In electric hearing, TLI for pulse trains with a fixed rate but varying number of pulses, i.e. stimulus duration, has mainly been investigated at clinically used stimulation rates. To study the effect of an overall effective stimulation rate at 100% channel crosstalk, we investigated TLI with (a) a clinically used single-channel stimulation rate of 1,500 pps and (b) a high stimulation rate of 18,000 pps, both for an apical and a basal electrode. Thresholds (THR), a line of equal loudness (BAL), and maximum acceptable levels (MALs) were measured in 10 MED-EL cochlear implant users. Stimulus durations varied from a single pulse to 300 ms long pulse trains. At 18,000 pps, the dynamic range (DR) increased by 7.36±3.16 dB for the 300 ms pulse train. Amplitudes at THR, BAL, and MAL decreased monotonically with increasing stimulus duration. The decline was fitted with high accuracy with a power law function (R2=0.94±0.06). Threshold slopes were -1.05±0.36 and -1.66±0.30 dB per doubling of duration for the low and high rate, respectively, and were shallower than for acoustic hearing. The electrode location did not affect the amplitudes or slopes of the TLI curves. THR, BAL, and MAL were always lower for the higher rate and the DR was larger at the higher rate at all measured durations.

Loudness constancy for noise and speech: How instructions and source information affect loudness of distant sounds.

The physical properties of a sound evolve when traveling away from its source. As an example, the sound pressure level at the listener's ears will vary according to their respective distance and azimuth. However, several studies have reported loudness to remain constant when varying the distance between the source and the listener. This loudness constancy has been reported to occur when the listener focused attention on the sound as emitted by the source (namely the distal stimulus). Instead, the listener can focus on the sound as reaching the ears (namely the proximal stimulus). The instructions given to the listener when assessing loudness can drive focus toward the proximal or distal stimulus. However, focusing on the distal stimulus requires to have sufficient information about the sound source, which could be provided by either the environment or by the stimulus itself. The present study gathers three experiments designed to assess loudness when driving listeners' focus toward the proximal or distal stimuli. Listeners were provided with different quality and quantity of information about the source depending on the environment (visible or hidden sources, free field or reverberant rooms) and on the stimulus itself (noise or speech). The results show that listeners reported constant loudness when asked to focus on the distal stimulus only, provided enough information about the source was available. These results highlight that loudness relies on the way the listener focuses on the stimuli and emphasize the importance of the instructions that are given in loudness studies.

Day-to-day loudness assessments of indoor soundscapes: Exploring the impact of loudness indicators, person, and situation.

This study investigates loudness perception in real-world contexts using predictors related to the sound, situation, or person. In the study, 105 participants recorded 6594 sound environments in their homes, which were then evaluated based on the Experience Sampling Method. Hierarchical linear regressions using a loudness level based on ISO 532-1 allowed for obtaining the best model fits for predicting perceived loudness and explaining the highest variance. LAeq and LAF5 provided comparable results and may require less computational effort. However, the analysis shows that only one-third of the variance explained by fixed effects was attributable to the loudness level. Sixteen percent stemmed from perceived properties of the soundscape; 1% were attributable to relatively temporally stable, person-related predictors like participants' age; non-auditory situational predictors made no additional contribution. The results thus did not confirm previous findings on loudness perception under laboratory conditions, emphasizing the importance of the situational context. Along with the current paper, a comprehensive dataset, including the assessed person-related, situational, and sound-related measures as well as LAeq time-series and third-octave spectrograms, is provided to enable further research on sound perception, indoor soundscapes, and emotion.

Relationships between fear of flying, loudness dependence of auditory evoked potentials and frontal alpha asymmetry.

Previous research has suggested that fear of flying, which is defined as a situational, specific phobia, could overlap with depressive and anxiety disorders. Whether the neuronal dysfunctions including altered serotonergic activity in the brain and altered neural oscillations observed for depressive and anxiety disorders also overlap with alterations in fear of flying is unclear. Here, thirty-six participants with self-reported fear of flying (FF) and forty-one unaffected participants (NFF) were recruited. The participants completed the Beck Depression Inventory (BDI-II), the State-trait Anxiety Inventory (STAI) and the Fear of Flying Scale (FFS). EEG-recording was conducted during resting-state and during presentation of auditory stimuli with varying loudness levels for analysis of the Loudness Dependence of Auditory Evoked Potentials (LDAEP), which is suggested to be inversely related to central serotonergic activity. Participants with fear of flying did not differ from the control group with regard to BDI-II and STAI data. The LDAEP was higher over F4 electrode in the FF group compared to controls, whereas exploratory analysis suggest that differences between groups were conveyed by female participants. Moreover, the FF group showed relatively higher right frontal alpha activity compared to the control group, whereas no difference in frequency power (alpha, beta and theta) was observed. Thus, this study brought the first hint for reduced serotonergic activity in individuals with fear of flying and relatively higher right frontal activity. Thus, based on the preliminary findings, future research should aim to examine the boundaries with anxiety and depressive disorders and to clarify the distinct neural mechanisms.

Investigation of hearing aid fitting according to the national acoustic laboratories' prescription for non-linear hearing aids and the desired sensation level methods in Japanese speakers: a crossover-controlled trial.

OBJECTIVE: Some studies have directly compared the National Acoustic Laboratories' prescription for non-linear hearing aids (HAs) version 2 (NAL-NL2) and Desired Sensation Level for non-linear HAs version 5 (DSLv5), although none were performed in Japan. As the Japanese language is a tonal language that has different linguistic characteristics than those of the studied languages, we compared the outcomes of the NAL-NL2 and DSLv5 in hearing-impaired Japanese participants. METHODS: A crossover-controlled trial was conducted on 18 first-time HA users with bilateral moderate sensorineural hearing loss. Participants wore HAs adjusted with each prescriptive method for four weeks. The prescriptions were assessed using speech discrimination testing and the abbreviated profile of hearing aid benefit (APHAB). Consequently, participants were asked to select their preferred prescription and determine which was better for "listening to a conversation" and when "noisy." RESULTS: The mean DSLv5 real ear insertion gain for an input level of 65 dB sound pressure level (SPL) was higher than that of the NAL-NL2 at 250 and 500 Hz. The average speech discrimination score was 78 ± 14% at a 65-dB SPL and 75 ± 17% at an 80-dB SPL for the NAL-NL2, and 79 ± 11% at a 65-dB SPL and 77 ± 17% at an 80-dB SPL for the DSLv5. These differences were not significant. No significant differences were observed in APHAB subscale scores between the two prescription methods. Ultimately, 11 (61%) and 7 (39%) participants preferred the NAL-NL2 and DSLv5, respectively, with no significant differences. CONCLUSION: Although the gain of the NAL-NL2 is smaller than that of the DSLv5, both had the same hearing effect. Therefore, the NAL-NL2 may be more useful than the DSLv5 in Japanese.

Investigation of Frequency-Specific Loudness Discomfort Levels in Listeners With Migraine: A Case-Control Study.

OBJECTIVES: Hypersensitivity to auditory stimuli is a commonly reported symptom in listeners with migraine, yet it remains relatively unexplored in research. This study aims to investigate loudness discomfort levels in listeners with migraine, while identifying the frequencies most affected by the phenomenon. DESIGN: To achieve this, the study compared just audible level and loudness discomfort level ranges between participants with and without migraine from the United Kingdom, Greece as well as the participant recruitment platform Prolific, across 13 frequencies from 100 to 12,000 Hz, through an online listening test. RESULTS: Fifty-five participants with migraine and 49 participants without migraine from both countries and Prolific were included in the analysis, where threshold ranges between just audible and mildly uncomfortable levels were compared in 13 frequencies. Migraineur group participants presented significantly smaller ranges between just audible and mildly uncomfortable level, due to lower thresholds of mild discomfort in 12 of the 13 frequencies when compared with the nonmigraineur group participants. Participants taking the test during their migraine attack or aura presented a tendency for smaller ranges. In addition, participants with self-reported higher severity migraine exhibited bigger ranges compared with participants with low severity migraine within the migraineur group. No relationship between ranges and medication or migraine attack frequency within the migraineur group was observed. CONCLUSIONS: Results from the study demonstrate a tendency for the migraineur group to present lower thresholds of mild discomfort compared with the nonmigraineur group, aligning with previous studies while extending the phenomenon to more frequencies than those previously examined. Though the present study presented no relationship between ranges and medication or attack frequency, further research is required to investigate a potential link between these factors.

Developmental Changes in the Perception of Vocal Loudness and Voice Quality in 3- to 6-Year-Old Children.

PURPOSE: The study's primary aim was to investigate developmental changes in the perception of vocal loudness and voice quality in children 3-6 years of age. A second aim was to evaluate a testing procedure-the intermodal preferential looking paradigm (IPLP)-for the study of voice perception in young children. METHOD: Participants were categorized in two age groups: 3- to 4-year-olds and 5- to 6-year-olds. Children were tested remotely via a Zoom appointment and completed two perceptual tasks: (a) voice discrimination and (b) voice identification. Each task consisted of two tests: a vocal loudness test and a voice quality test. RESULTS: Children in the 5- to 6-year-old group were significantly more accurate than children in the 3- to 4-year-old group in discriminating and identifying differences between voices for both loudness and voice quality. The IPLP, used in the identification task, was found to successfully detect differences between the age groups for overall accuracy and for most of the sublevels of vocal loudness and voice quality. CONCLUSIONS: Results suggest that children's ability to discriminate and identify differences in vocal loudness and voice quality improves with age. Findings also support the use of the IPLP as a useful tool to study voice perception in young children.

Stimulation Rate and Voice Pitch Perception in Cochlear Implants.

The stimulation rate in cochlear implant (CI) sound coding, or the "carrier" rate in pulses per second (pps), is known to influence pitch perception, as well as loudness perception and sound quality. Our main objective was to investigate the effects of reduced carrier rate on the loudness and pitch of coded speech samples. We describe two experiments with 16 Nucleus® CI users, where we controlled modulation characteristics and carrier rate using Spectral and Temporal Enhanced Processing (STEP), a novel experimental multichannel sound coder. We used a fixed set of threshold and comfortable stimulation levels for each subject, obtained from clinical MAPs. In the first experiment, we determined equivalence for voice pitch ranking and voice gender categorization between the Advanced Combination Encoder (ACE), a widely used clinical strategy in Nucleus® recipients, and STEP for fundamental frequencies (F0) 120-250 Hz. In the second experiment, loudness was determined as a function of the input amplitude of speech samples for carrier rates of 1000, 500, and 250 pps per channel. Then, using equally loud sound coder programs, we evaluated the effect of carrier rate on voice pitch perception. Although nearly all subjects could categorize voice gender significantly above chance, pitch ranking varied across subjects. Overall, carrier rate did not substantially affect voice pitch ranking or voice gender categorization: as long as the carrier rate was at least twice the fundamental frequency, or when stimulation pulses for the lowest, 250 pps carrier were aligned to F0 peaks. These results indicate that carrier rates as low as 250 pps per channel are sufficient to support functional voice pitch perception for those CI users sensitive to temporal pitch cues; at least when temporal modulations and pulse timings in the coder output are well controlled by novel strategies such as STEP.

Behavioural and Electrophysiological Evaluation of Loudness Growth in Clinically Normal Hearing Tinnitus Patients with and without Hyperacusis.

INTRODUCTION: The common mechanism of tinnitus, hyperacusis, and loudness perception is hypothesized to be related to central gain. Although central gain increases with attempts to compensate hearing loss, reduced input can also be observed in those with clinically normal hearing. This study aimed to evaluate the loudness growth function of tinnitus patients with and without hyperacusis using behavioural and electrophysiological methods. METHODS: The study consists of three groups with a total of 60 clinically normal hearing subjects, including the control group (10 men and 10 women; mean age 39.8, SD 11.8 years), tinnitus group (10 men and 10 women; mean age 40.9, SD 12.2 years), and hyperacusis group (also have tinnitus) (7 men and 13 women; mean age 38.7, SD 14.6 years). Loudness discomfort levels (LDLs), categorical loudness scaling (CLS), and cortical auditory evoked potentials were used for the evaluation of loudness growth. N1-P2 component amplitudes and latencies were measured. RESULTS: LDL results of 500, 1,000, 2,000, 4,000, and 8,000 Hz showed a significant difference between the hyperacusis group and the other two groups (p < 0.001). In the loudness scale test performed with 500 Hz and 2,000 Hz narrow-band noise (NBN) stimulus, a significant difference was observed between the hyperacusis group and the other two groups in the "medium," "loud," and "very loud" categories (p < 0.001). In the cortical examination performed with 500 Hz and 2,000 Hz NBN stimulus at 40, 60, and 80 dB nHL intensities, no significant difference was observed between the groups in the N1, P2 latency, and N1-P2 peak-to-peak amplitude. CONCLUSION: Although the hyperacusis group is significantly different between groups in behavioural tests, the same cannot be said for electrophysiological tests. In our attempt to differentiate tinnitus and hyperacusis with electrophysiological tests over the loudness growth function, N1 and P2 responses were not seen as suitable methods. However, it appears to be beneficial to use CLS in addition to LDLs in behavioural tests.

Influencing Factors Identification and Prediction of Noise Annoyance-A Case Study on Substation Noise.

Noise-induced annoyance is one person's individual adverse reaction to noise. Noise annoyance is an important basis for determining the acceptability of environmental noise exposure and for formulating environmental noise standards. It is influenced by both acoustic and non-acoustic factors. To identify non-acoustic factors significantly influencing noise annoyance, 40 noise samples with a loudness level of 60-90 phon from 500-1000 kV substations were selected in this study. A total of 246 subjects were recruited randomly. Using the assessment scale of noise annoyance specified by ISO 15666-2021, listening tests were conducted. Meanwhile, basic information and noise sensitivity of each subject were obtained through a questionnaire and the Weinstein's noise sensitivity scale. Based on the five non-acoustic indices which were identified in this study and had a significant influence on noise annoyance, a prediction model of annoyance from substation noise was proposed by a stepwise regression. Results showed that the influence weight of acoustic indices in the model accounted for 80% in which the equivalent continuous A-weighted sound pressure level and the sound pressure level above 1/1 octave band of 125 Hz were 65% and 15%, respectively. The influence weight of non-acoustic indices entering the model was 20% in which age, education level, noise sensitivity, income, and noisy degree in the workplace were 8%, 2%, 4%, 4%, and 2%, respectively. The result of this study can provide a basis for factors identification and prediction of noise annoyance.

Association between the loudness dependence of auditory evoked potentials and age in patients with schizophrenia and depression.

OBJECTIVE: Although serotonergic dysfunction is significantly associated with major depressive disorder (MDD) and schizophrenia (SCZ), comparison of serotonergic dysfunction in both diseases has received little attention. Serotonin hypotheses have suggested diminished and elevated serotonin activity in MDD and SCZ, respectively. However, the foundations underlying these hypotheses are unclear regarding changes in serotonin neurotransmission in the aging brain. The loudness dependence of auditory evoked potentials (LDAEP) reflects serotonin neurotransmission. The present study compared the LDAEP between patients with SCZ or MDD and healthy controls (HCs). We further examined whether age was correlated with the LDAEP and clinical symptoms. METHODS: This prospective clinical study included 105 patients with SCZ (n = 54) or MDD (n = 51). Additionally, 35 HCs were recruited for this study. The LDAEP was measured on the midline channels via 62 electroencephalography channels. RESULTS: Patients with SCZ or MDD showed a significantly smaller mean LDAEP than those in HCs. The LDAEP was positively correlated with age in patients with SCZ or MDD. CONCLUSIONS: Changes in central serotonergic activity could be indicated by evaluating the LDAEP in patients with SCZ or MDD. Age-related reductions in serotonergic activity may be screened using the LDAEP in patients with SCZ or MDD.