Sound Stimulation Research Articles

Exploring the therapeutic potential of bi-modal stimulation for tinnitus

Background: Tinnitus is the perception of sound without any external acoustic stimuli, affecting over 10% of the population, especially older adults. Current treatments focus on symptom management rather than a complete cure, often providing limited relief. Objective: To evaluate the efficacy and safety of bimodal neuromodulation therapy for tinnitus, compared to traditional treatment methods. Results: Bimodal neuromodulation, which combines sound and tongue stimulation, has shown significant improvement in tinnitus symptoms. FDA-approved studies report sustained symptom reduction in over 77% of patients for up to 12 months. The most common side effect is an increase in tinnitus symptoms, similar to sound-only treatments. Conclusion: This therapy presents a high benefit-to-risk ratio with minimal side effects, offering better clinical outcomes and patient satisfaction compared to existing treatments. Adjustments in treatment parameters can further enhance its effectiveness over time. Bimodal neuromodulation shows promise as a more effective treatment for tinnitus. Future clinical trials should replicate these positive findings, evaluate long-term effects, and compare their effectiveness to other treatment options to improve accessibility and clinical outcomes for tinnitus patients.

Single-session gamma sensory stimulation entrains real-time electroencephalography but does not enhance perception, attention, short-term memory, or long-term memory

Background Studies have shown that gamma (40 Hz) audiovisual stimulation can enhance gamma oscillations and improve cognitive functioning in patients with Alzheimer's disease. However, despite promising long-term results, the efficacy of short-duration or single-session 40 Hz entrainment in humans has been questioned by behavioral studies that fail to find observable cognitive aftereffects, for two possible reasons: 1) lack of validated gamma entrainment, as most studies lacked concurrent electroencephalography (EEG) data to verify that gamma neural entrainment did take place, and 2) lack of diverse cognitive tests, as most studies did not test a wide range of cognitive factors. Objective This study aimed to increase sensitivity for detecting single-session gamma entrainment. We employed 1) mid- and post-stimulation EEG monitoring to ensure entrainment worked, and 2) a comprehensive cognitive battery that probes perception, attention, working memory, and long-term memory. Methods Participants received 30 min of synchronized 40 Hz light and sound stimulation, followed by a visual perceptual task, attentional network task, change detection working memory task, and long-term picture memory task, with concurrent EEG. Results We observed robust 40 Hz EEG entrainment during stimulation but no significant 40 Hz oscillation after stimulation, and no significant cognitive improvements. Conclusions Despite robust 40 Hz online entrainment, gamma sensory entrainment requires consistent long-term exposure to induce cognitive and neurological changes. Future research should determine the optimal duration and frequency of 40 Hz stimulation to maximize its therapeutic potential.

Effect of specific sound frequency on production performance, egg quality and physiological characteristics of laying hens

The study investigated the effects of violin note B7 (Violin), double bass note E1 (Bass) and Mozart’s Sonata for Two Pianos in D Major, K. 448 (Mozart), on laying hens in terms of the production performance, egg quality and physiological characteristics. One hundred and sixty 600-day-old laying hens (ISA Brown) were randomly categorised into four groups with four replicates (10 hens/ replicate), and exposed to specific sound frequency for 12 weeks. The results indicated that Violin group presented significantly higher thick albumin height, Haugh unit and yolk index compared to the control group (p < .05). The treatment groups exhibited higher level of glutathione peroxidase in the jejunum–ileum and serum compared to the control group (p < .05). The Violin and Bass groups displayed lower levels of interleukin (IL)-1β in the jejunum–ileum, while the levels of IL-6 were lower in treatment groups compared to the control group (p < .05). The expression of the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) gene was lower in the treatment groups than the control group (p < .05). Bass and Mozart groups exhibited lower messenger RNA (mRNA) level of inducible nitric oxide synthase (iNOS) and tumour necrosis factor-α (TNF-α) compared to those in the control group. The number of ASVs (amplicon sequence variants) in the jejunum–ileum of the Violin group was three times higher than that in the control group. These observations suggest that specific sound frequency stimulation can enhance the egg quality and also aid in regulating oxidative stress of laying hens.

Behavioural and electrophysiological features of WAG/Rij rats with different forms of genetic epilepsy

WAG/Rij rats are widely used as a genetic model of absence epilepsy. Approximately 15–50% rats of the strain are susceptible to audiogenic seizures. WAG/Rij rats demonstrate depressive-like behavior. After preliminary sound provocation an increased level of anxiety was found in audiogenic susceptible WAG/Rij subgroup. Electrophysiological and behavioral studies suggest the involvement of the dopaminergic system in both absence and audiogenic epilepsy. An increased binding density to dopamine receptors was found in the dorsal striatum subregions in audiogenic prone rats compared to non-audiogenic. The study aims were (1) to determine whether behavioral changes in WAG/Rij rats were genetically determined or induced by prior sound stimulation; (2) how regions of the dorsal striatum with different density of dopamine receptors in subpopulations of WAG/Rij rats are involved in the absence epilepsy control. The study was conducted using two rat groups: WAG/Rij-nonAGS (absence epilepsy) and WAG/Rij-AGS (mixed epilepsy). The study was performed using tests: “Elevated plus maze”, “Forced swimming” and “Three chamber sociability test”. High-frequency deep brain stimulation was performed for evaluation of dorsal striatum involvement in the absence seizure control. After experiments animals were tested for the susceptibility to audiogenic seizures. It demonstrated that the increased level of anxiety in WAG/Rij-AGS rats is genetically determined, while depressive-like behavior in WAG/Rij rats is not dependent on a predisposition to audiogenic seizures. Deviations in social behavior were observed in WAG/Rij-AGS rats. Stimulation of the dorsal striatum indicates differences in the control of absence and mixed forms of epilepsy in the

Avoidance behavior of grass carp (Ctenopharyngodon idella) shoals to low-frequency sound stimulation

Avoidance behavior of grass carp (Ctenopharyngodon idella) shoals to low-frequency sound stimulation

Tympanic Pre-Operative Electrically Evoked Auditory Late Response (TympEALR) as an Alternative to Trans-Tympanic Tests Using Anesthesia in Cochlear Implant Candidacy.

Background/Objectives: Before a cochlear implant is considered, patients undergo various audiological tests to assess their suitability. One key test measures the auditory brainstem response (ABR) to acoustic stimuli. However, in some cases, even with maximum sound stimulation, no response is detected. Methods: The promontory test involves electrical stimulation near the auditory nerve, allowing patients to associate the sensation. Ideally, the electrode is placed in the middle ear after opening the eardrum. This method, along with trans-tympanic electrically evoked ABR in local anesthesia (LA-TT-EABR) and the cortical equivalent (LA-TT-EALR), helps assess the auditory nerve's existence and excitability. The TympEALR test, utilizing a "tympanic LA-TT-EALR", provides an alternative measurement. Previous research has shown the possibility of deriving brainstem and cortical potentials through trans-tympanic electrical stimulation, allowing for objective assessment of the auditory nerve's integrity and potentially objectifying patient sensations. Results: Sixteen patients have been tested using TympEALR. In seven of these, we found a positive response. The morphology was similar to other electrically evoked cortical auditory responses (EALR), e.g., using cochlear implants or trans-tympanic stimulation electrodes. We observed a higher influence of electrical artifacts than in other EALRs. Conclusions: TympEALR showed positive results in nearly half of the study participants, potentially avoiding invasive procedures. TympEALR can be a valuable alternative to trans-tympanic methods. More research is needed to determine if a negative result suggests against cochlear implantation.

Low-side and multi-tone suppression in the base of the gerbil cochlea

The cochlea’s mechanical response to sound stimulation is nonlinear, likely due to saturation of the mechano-electric transduction current that is part of an electromechanical feedback loop. The ability of a second tone or tones to reduce the response to a probe tone is one manifestation of nonlinearity, termed suppression. Using optical coherence tomography to measure motion within the organ of Corti, regional motion variations have been observed. Here, we report on the suppression that occurs within the organ of Corti when a high sound level, low frequency suppressor tone was delivered along with a sweep of discreet single-tones. Responses were measured in the base of the gerbil cochlea at two best frequency locations, with two different directions of observation relative to the sensory tissue’s anatomical axes. Suppression extended over a wide frequency range in the outer hair cell region, whereas it was typically limited to the best frequency peak in the reticular lamina region and at the basilar membrane. Aspects of the observed suppression were consistent with the effect of a saturating nonlinearity. Recent measurements have noted the three-dimensional nature of organ of Corti motion. The effects of suppression observed here could be due to a combination of reduced motion amplitude and altered vibration axis.

Spinal Regulation of Posture: Effects of Transcutaneous Spinal Cord and Affective Sound Stimulation.

The combined effects of transcutaneous electrical stimulation (tES) of the spinal cord and affective sound stimulation on postural control were investigated to elucidate the involvement of spinal networks in the maintenance of vertical stability. Healthy volunteers (n = 27) underwent tES and sound stimulation separately and combined quasi-randomly. All participants were field-dependent; i.e., participants used the exteroceptive afferent stream for spatial orientation. Centre-of-pressure parameters were analysed to assess postural stability. Results showed that tES at the T11-T12 vertebrae stabilised posture, tES at the L1-L2 vertebrae had no postural effect, and sound stimulation from the left destabilised posture. To assess the role of spinal regulation of postural disturbances, we compared the effects of combined tES with sound stimulation to those of sound stimulation alone. Stimulation at the T11-T12 level reduced the lateral sway induced by affective sounds, whereas L1-L2 tES did not. These results suggest that, in healthy individuals, spinal networks located at the T11-T12 and L1-L2 vertebral levels have distinct roles in maintaining upright posture, both when a person is standing still and when they are actively stabilising their posture during destabilising perturbations. T11-T12 spinal networks stabilise upright posture when destabilising information is solely transmitted from the supraspinal level.

Lack of Amino Acid Alterations Within the Cochlear Nucleus and the Auditory Cortex in Acoustic Trauma-Induced Tinnitus Rats Using In Vivo Microdialysis.

Background/Objectives: Tinnitus is a debilitating auditory disorder commonly described as a ringing in the ears in the absence of an external sound source. Sound trauma is considered a primary cause. Neuronal hyperactivity is one potential mechanism for the genesis of tinnitus and has been identified in the cochlear nucleus (CN) and the auditory cortex (AC), where there may be an imbalance of excitatory and inhibitory neurotransmissions. However, no study has directly correlated tinnitus with the extracellular levels of amino acids in the CN and the AC using microdialysis, which reflects the functions of these neurochemicals. In the present study, rats were exposed to acoustic trauma and then subjected to behavioural confirmation of tinnitus after one month, followed by microdialysis. Methods: Rats were divided into sham (aged, n = 6; young, n = 6); tinnitus-positive (aged, n = 7; young, n = 7); and tinnitus-negative (aged, n = 3; young, n = 3) groups. In vivo microdialysis was utilized to collect samples from the CN and the AC, simultaneously, in the same rat. Extracellular levels of amino acids were quantified using high-performance liquid chromatography (HPLC) coupled with an electrochemical detector (ECD). The effects of sound stimulation and age on neurochemical changes associated with tinnitus were also examined. Results: There were no significant differences in either the basal levels or the sound stimulation-evoked changes of any of the amino acids examined in the CN and the AC between the sham and tinnitus animals. However, the basal levels of serine and threonine exhibited age-related alterations in the AC, and significant differences in threonine and glycine levels were observed in the responses to 4 kHz and 16 kHz stimuli in the CN. Conclusions: These results demonstrate the lack of a direct link between extracellular levels of amino acids in the CN and the AC and tinnitus perception in a rat model of tinnitus.

Association between nasal septal deviation and tinnitus: Insights from a 9-year nationwide cohort study.

Tinnitus is a condition where sound is perceived in the ear or head when no external sound stimulation is present. To date, no study has explored the correlation between nasal septal deviation (SD) and tinnitus using large-scale real-world data. This study hypothesized a potential relationship between tinnitus and SD, which we investigated using a 9-year large-scale cohort study. Nationwide cohort observational study. The SD group was selected from 1 million individuals randomly extracted from the National Health Insurance Service database. The non-SD group was obtained through propensity score matching considering several variables. The primary endpoint was tinnitus diagnosis. The study (SD) group included 10,790 individuals, and the non-SD group (control group) included 21,580 individuals. The overall hazard ratio (HR) for tinnitus in the SD group was 1.74 (95% CI: 1.62-1.89). In the subgroup analysis, the HR was 0.73 (95% CI: 0.68-0.79) for tinnitus in the male group, 1.12 (95% CI: 1.04-1.21) in the group with high economic status, 0.81 (95% CI: 0.75-0.89) in the group living in metropolitan areas, and 0.45 (95% CI: 0.42-0.49) in the younger age group (<50 years). In the SD group, the HR for tinnitus after septoplasty significantly decreased to 0.75 (95% CI: 0.63-0.90). From long-term follow-up, the prevalence of tinnitus was 1.74 times higher in the SD group compared with the control group. This phenomenon significantly decreased after septoplasty.

Reduced auditory perception and brain response with quiet TMS coil

BackgroundElectromagnetic forces in transcranial magnetic stimulation (TMS) coils generate a loud clicking sound that produces confounding auditory activation and is potentially hazardous to hearing. To reduce this noise while maintaining stimulation efficiency similar to conventional TMS coils, we previously developed a quiet TMS double containment coil (qTMS-DCC). ObjectiveTo compare the stimulation strength, perceived loudness, and EEG response between qTMS-DCC and a commercial TMS coil. MethodsNine healthy volunteers participated in a within-subject study design. The resting motor thresholds (RMTs) for qTMS-DCC and MagVenture Cool-B65 were measured. Psychoacoustic titration matched the Cool-B65 loudness to qTMS-DCC pulsed at 80, 100, and 120 % RMT. Event-related potentials (ERPs) were recorded for both coils. The psychoacoustic titration and ERPs were acquired with the coils both on and 6 cm off the scalp, the latter isolating the effects of airborne auditory stimulation from body sound and electromagnetic stimulation. The ERP comparisons focused on a centro-frontal region that encompassed peak responses in the global signal while stimulating the primary motor cortex. ResultsRMT did not differ significantly between the coils, with or without the EEG cap on the head. qTMS-DCC was perceived to be substantially quieter than Cool-B65. For example, qTMS-DCC at 100 % coil-specific RMT sounded like Cool-B65 at 34 % RMT. The general ERP waveform and topography were similar between the two coils, as were early-latency components, indicating comparable electromagnetic brain stimulation in the on-scalp condition. qTMS- DCC had a significantly smaller P180 component in both on-scalp and off-scalp conditions, supporting reduced auditory activation. ConclusionsThe stimulation efficiency of qTMS-DCC matched Cool-B65 while having substantially lower perceived loudness and auditory-evoked potentials.

Two cues are better than one: Adding interaural time differences improves spatial hearing for bilateral cochlear-implant listeners

Bilateral cochlear-implant (BI-CI) listeners show limited sensitivity to interaural time differences (ITDs), the dominant localization cue for acoustic-hearing listeners, and mainly rely on interaural level differences (ILDs) for localization. Studies utilizing bilaterally synchronized direct stimulation capable of conveying ITDs have investigated sensitivity to ITDs or ILDs in isolation. It is, however, unclear how these two cues interact in controlled and bilaterally synchronized electrical stimulation. Therefore, this study performed an ITD-ILD cue-weighting lateralization experiment with BI-CI listeners using direct stimulation of single electrodes. Preliminary results show that BI-CI listeners display sensitivity only to ILDs with unsynchronized stimulation and equal sensitivity to both ITDs and ILDs with synchronized stimulation. Additionally, providing ITDs and ILDs together via bilaterally synchronized stimulation resulted in increased lateralization ranges and slopes, thus improved spatial hearing acuity compared to either cue alone. These results suggest providing both ITDs and ILDs via bilaterally synchronized sound processors has the potential to improve spatial hearing in BI-CI listeners. The data have implications for clinical sound processor design and stimulation strategies.

Sonic restoration: acoustic stimulation enhances plant growth-promoting fungi activity.

Ecosystem restoration interventions often utilize visible elements to restore an ecosystem (e.g. replanting native plant communities and reintroducing lost species). However, using acoustic stimulation to help restore ecosystems and promote plant growth has received little attention. Our study aimed to assess the effect of acoustic stimulation on the growth rate and sporulation of the plant growth-promoting fungus Trichoderma harzianum Rifai, 1969. We played a monotone acoustic stimulus (80 dB sound pressure level (SPL) at a peak frequency of 8 kHz and a bandwidth at -10 dB from the peak of 6819 Hz-parameters determined via review and pilot research) over 5 days to T. harzianum to assess whether acoustic stimulation affected the growth rate and sporulation of this fungus (control samples received only ambient sound stimulation less than 30 dB). We show that the acoustic stimulation treatments resulted in increased fungal biomass and enhanced T. harzianum conidia (spore) activity compared to controls. These results indicate that acoustic stimulation influences plant growth-promoting fungal growth and potentially facilitates their functioning (e.g. stimulating sporulation). The mechanism responsible for this phenomenon may be fungal mechanoreceptor stimulation and/or potentially a piezoelectric effect; however, further research is required to confirm this hypothesis. Our novel study highlights the potential of acoustic stimulation to alter important fungal attributes, which could, with further development, be harnessed to aid ecosystem restoration and sustainable agriculture.

An acoustic bellows-type round window transducer for middle-ear implants

BackgroundThis study describes the development of output devices for round window middle-ear. To overcome the problems of output devices that apply sound pressure directly to the round window, an acoustic bellows-type round window transducer was implemented by combining a small bellows, acoustic tube, and balanced armature driver. MethodsThe output characteristics of the proposed acoustic bellows-type round window transducer were confirmed through bench tests and distortion measurements. To compare the vibration transmission characteristics of the proposed transducer with those of sound pressure stimulation devices, an experiment was performed using four human temporal bones. FindingsThe average output magnitude of the acoustic bellows-type round window transducer was equivalent to sound pressure levels of 92, 96, and 108 dB for frequency ranges of <1, 1–2, and > 2 kHz, respectively. The results showed that the proposed transducer delivered vibration consistently without reducing the sound pressure level due to leakage, unlike the sound pressure stimulation device. InterpretationTherefore, the acoustic bellows-type round window transducer is a more stable and suitable output device for round window middle-ear implants than a sound pressure stimulation device. It is expected to overcome the limitations of sound pressure stimulation devices and to contribute to new technical solutions in the field of round window middle-ear implants development.

Effects of monaural sound stimulation on subjective visual vertical.

Sound stimulation can influence electrophysiological vestibular reflexes. However, the effects of sound stimulation on space perception remain unknown. To know the effects of monaural sound stimulation on subjective visual vertical (SVV). We measured SVV with and without monaural sound stimulation (105 dB, 500 Hz short tone burst presented at 4.7 Hz) in 50 healthy volunteers (aged 20-77 [mean = 42.7] years). The mean SVV was deviated 0.139° to the left by right monaural sound stimulation and 0.123° to the right by left monaural sound stimulation. SVV changes due to right and left ear stimulations were significantly different (p = 0.019). Sound stimulation resulted in a significant change in SVV on the left side (p = 0.014) in participants aged 50 or younger (mean = 35.6 years) (n = 37). This study is the first to show the possibility that the monaural sound input deviates the SVV toward the opposite side and is more pronounced for left-ear input. The vestibular-evoked myogenic potential responses may be involved in the mechanism of the contralateral SVV deviation due to sound input.

Concurrent abnormalities in galvanic cervical and ocular vestibular-evoked myogenic potentials as a predictive marker for prolonged dizziness in vestibular neuritis

Background Despite the growing use of cervical (cVEMP) and ocular (oVEMP) VEMP tests, their effectiveness in predicting chronic dizziness in vestibular neuritis (VN) patients remains unclear. Our research examines the link between long-lasting dizziness and inner ear assessments, encompassing VEMPs induced by air-conducted sound (ACS), bone-conducted vibration (BCV), and galvanic vestibular stimulation (GVS). Objectives This study explores prognostic markers by examining the relationship between the persistence of dizziness symptoms and various inner ear test findings in VN patients. Material and methods A retrospective cohort of 60 unilateral VN patients underwent comprehensive audiovestibular tests, including pure tone audiometry, cVEMP and oVEMP induced by ACS, BCV, GVS, and caloric tests. Patient subgroups were established based on dizziness duration: short-term (<3 months) and long-term (≥3 months). Results No substantial correlation existed between the dizziness duration and the outcomes of any particular single inner ear test. However, patients exhibiting concurrent abnormal GVS-cVEMP and GVS-oVEMP were more likely to experience prolonged dizziness, indicating more extensive vestibular system involvement. Conclusions Concurrent abnormalities in GVS-cVEMP and GVS-oVEMP may indicate a higher chance of long-term dizziness in VN. Significance This study identifies concurrent abnormalities in GVS-cVEMP and GVS-VEMP as a potential prognostic marker for prolonged dizziness in VN.

Synthesis of non-peripheral phthalocyanine sensitizers and investigation of the effect of ultrasound-light stimulus synergy on singlet oxygen production

The high singlet oxygen production capacity and other unique properties of phthalocyanines allow these compounds to be widely used as sensitizers in photodynamic therapy (PDT) and sonodynamic therapy (SDT) in the treatment of cancer. Sono-photodynamic therapy (SPDT), which uses a combination of light and sound stimulation together and has a very high therapeutic effect compared to PDT, is an increasingly important new method for cancer treatment. Published studies on the application of non-peripherally phthalocyanines in SPDT are limited in the literature. With this in mind, in this study, the synthesis and characterization of novel non-peripherally tetra-substituted (4-tert-butylbenzyl)oxy) metal-free (2), Mg(II) (3), Zn(II) (4), and In(III)CI (5) phthalocyanines and their potential as a sono-photosensitizer in SPDT applications as well as PDT applications were determined. Comparative photochemical and sono-photochemical studies showed that the singlet oxygen quantum yields of the synthesised phthalocyanine compounds were calculated as 0.027, 0.22, 0.29 and 0.32 for 2, 3, 4 and 5 respectively, by photochemical studies using only light irradiation, while these values increased to 0.11, 0.28, 0.58 and 0.64 for 2, 3, 4 and 5 respectively, by sono-photochemical studies after the synergistic effect of light and ultrasound. These results showed that the combined use of ultrasound waves and light as a stimulation method exhibited a more effective therapeutic effect compared to light stimulation alone. According to the singlet oxygen efficiency, it was shown that the presence of a metal ion on the phthalocyanine ring increased the singlet oxygen production in both methods.

Climbing Fiber Activation Induced by Footshock in the Cerebellar Vermis Lobule IV/V of Freely Moving Mice.

Parallel fibers (PFs) in the cerebellar cortex are involved in a series of coordinated responses in the fear conditioning paradigm induced by footshock. However, whether footshock can activate cerebellar climbing fibers (CFs) remains unclear. In this study, we recorded calcium (Ca2+) activity in CFs by optical fiber photometry in the cerebellar vermis lobule IV/V of freely moving mice with footshock stimulation. We found that the activation of CFs in the lobule IV/V was highly correlated with footshock stimulation but not with the sound stimulation used as a control. This result suggests that afferent information from CFs might be associated with the motor initiation of fear-related behaviors or fear emotion itself. Thus, our results suggest that a characteristic CF signal in the cerebellar cortex might be related to fear processing or footshock-related behaviors (such as startle responses or pain sensation).

Myogenic artifacts masquerade as neuroplasticity in the auditory frequency-following response.

The frequency-following response (FFR) is an evoked potential that provides a neural index of complex sound encoding in the brain. FFRs have been widely used to characterize speech and music processing, experience-dependent neuroplasticity (e.g., learning and musicianship), and biomarkers for hearing and language-based disorders that distort receptive communication abilities. It is widely assumed that FFRs stem from a mixture of phase-locked neurogenic activity from the brainstem and cortical structures along the hearing neuraxis. In this study, we challenge this prevailing view by demonstrating that upwards of ~50% of the FFR can originate from an unexpected myogenic source: contamination from the postauricular muscle (PAM) vestigial startle reflex. We measured PAM, transient auditory brainstem responses (ABRs), and sustained frequency-following response (FFR) potentials reflecting myogenic (PAM) and neurogenic (ABR/FFR) responses in young, normal-hearing listeners with varying degrees of musical training. We first establish that PAM artifact is present in all ears, varies with electrode proximity to the muscle, and can be experimentally manipulated by directing listeners' eye gaze toward the ear of sound stimulation. We then show this muscular noise easily confounds auditory FFRs, spuriously amplifying responses 3-4-fold with tandem PAM contraction and even explaining putative FFR enhancements observed in highly skilled musicians. Our findings expose a new and unrecognized myogenic source to the FFR that drives its large inter-subject variability and cast doubt on whether changes in the response typically attributed to neuroplasticity/pathology are solely of brain origin.

Reduced Auditory Perception and Brain Response with Quiet TMS Coil.

Electromagnetic forces in transcranial magnetic stimulation (TMS) coils generate a loud clicking sound that produces confounding auditory activation and is potentially hazardous to hearing. To reduce this noise while maintaining stimulation efficiency similar to conventional TMS coils, we previously developed a quiet TMS double containment coil (qTMS-DCC). To compare the stimulation strength, perceived loudness, and EEG response between qTMS-DCC and a commercial TMS coil. Nine healthy volunteers participated in a within-subject study design. The resting motor thresholds (RMTs) for qTMS-DCC and MagVenture Cool-B65 were measured. Psychoacoustic titration matched the Cool-B65 loudness to qTMS-DCC pulsed at 80, 100, and 120% RMT. Event-related potentials (ERPs) were recorded for both coils. The psychoacoustic titration and ERPs were acquired with the coils both on and 6 cm off the scalp, the latter isolating the effects of airborne auditory stimulation from body sound and electromagnetic stimulation. The ERP comparisons focused on a centro-frontal region that encompassed peak responses in the global signal. RMT did not differ significantly between the coils, with or without the EEG cap on the head. qTMS-DCC was perceived to be substantially quieter than Cool-B65. For example, qTMS-DCC at 100% coil-specific RMT sounded like Cool-B65 at 34% RMT. The general ERP waveform and topography were similar between the two coils, as were early-latency components, indicating comparable electromagnetic brain stimulation in the on-scalp condition. qTMS-DCC had a significantly smaller P180 component in both on-scalp and off-scalp conditions, supporting reduced auditory activation. The stimulation efficiency of qTMS-DCC matched Cool-B65, while having substantially lower perceived loudness and auditory-evoked potentials. qTMS coil is subjectively and objectively quieter than conventional Cool-B65 coilqTMS coil at 100% motor threshold was as loud as Cool-B65 at 34% motor thresholdAttenuated coil noise reduced auditory N100 and P180 evoked response componentsqTMS coil enables reduction of auditory activation without masking.