Measuring "Where": A Comparative Analysis of Methods Measuring Spatial Perception.

The literature offers various methods for measuring sound localization. In this study, we aimed to compare these methods to determine their effectiveness in addressing different research questions by examining the effect sizes obtained from each measure. Data from 150 participants who identified the location of a sound source were analyzed to explore the effects of speaker angle, stimuli, HPD type, and condition (with/without HPD) on sound localization, using six methods for analysis: mean absolute deviation (MAD), root-mean-squared error (RMSE), very large errors (VLE), percentage of errors larger than the average error observed in a group of participants (pMean), percentage of errors larger than half the distance between two consecutive loudspeakers (pHalf), and mirror image reversal errors (MIRE). Results indicated that the MIRE measure was the most sensitive to the effects of speaker angle and HPD type, while the VLE measure was most sensitive to the effect of stimuli type. The condition variable provided the largest effect sizes, with no difference observed between measures. The data suggest that when effect sizes are substantial, all methods are adequate. However, for cases where the effect size is expected to be small, methods that yield larger effect sizes should be considered, considering their alignment with the research question.

Thermographic Changes following Short-Term High-Intensity Anaerobic Exercise.

Current studies report thermographic changes following aerobic or resistance exercise but not short, vigorous anaerobic exercise. Therefore, we investigated body surface temperature changes using thermal imaging following a short session of anaerobic exercise. We studied three different regions of interest (ROIs): the legs, chest, and forehead. Thermal imaging for each participant was performed before and immediately after completing a Wingate anaerobic test and every minute during a 15 min recovery period. Immediately after the test, the maximum temperature was significantly higher in all ROIs (legs, p = 0.0323; chest, p = 0.0455; forehead, p = 0.0444) compared to pre-test values. During the recovery period, both legs showed a significant and continuous temperature increase (right leg, p = 0.0272; left leg, p = 0.0382), whereas a non-significant drop was noted in the chest and forehead temperatures. Additionally, participants with a lower anaerobic capacity exhibited a higher delta increase in surface leg temperature than participants with higher anaerobic capacities, with a minimal change in surface leg temperature. This is the first study to demonstrate body surface temperature changes following the Wingate anaerobic test. This temperature increase is attributed to the high anaerobic mechanical power outputs achieved by the leg muscles and the time taken for temperature reduction post-exercise.

Perforated Concave Earplug (pCEP): A Proof-of-Concept Earplug to Improve Sound Localization without Compromising Noise Attenuation.

Combat soldiers are currently faced with using a hearing-protection device (HPD) at the cost of adequately detecting critical signals impacting mission success. The current study tested the performance of the Perforated-Concave-Earplug (pCEP), a proof-of-concept passive HPD consisting of a concave bowl-like rigid structure attached to a commercial roll-down earplug, designed to improve sound localization with minimal compromising of noise attenuation. Primarily intended for combat/military training settings, our aim was an evaluation of localization of relevant sound sources (single/multiple gunfire, continuous noise, spoken word) compared to 3M™-Combat-Arms™4.1 earplugs in open-mode and 3M™-E-A-R™-Classic™ earplugs. Ninety normal-hearing participants, aged 20-35 years, were asked to localize stimuli delivered from monitors evenly distributed around them in no-HPD and with-HPD conditions. The results showed (1) localization abilities worsened using HPDs; (2) the spoken word was localized less accurately than other stimuli; (3) mean root mean square errors (RMSEs) were largest for stimuli emanating from rear monitors; and (4) localization abilities corresponded to HPD attenuation levels (largest attenuation and mean RMSE: 3M™-E-A-R™-Classic™; smallest attenuation and mean RMSE: 3M™-Combat-Arms™4.1; pCEP was mid-range on both). These findings suggest that the pCEP may benefit in military settings by providing improved sound localization relative to 3M™ E-A-R™-Classic™ and higher attenuation relative to 3M™-Combat Arms™-4.1, recommending its use in noisy environments.

The Effect of Hearing Aids on Sound Localization in Mild Unilateral Conductive Hearing Loss.

BACKGROUND: Binaural hearing is of utmost importance for communicating in noisy surroundings and localizing the direction of sound. Unilateral hearing loss (UHL) affects the quality of life in both childhood and adulthood, speech development, and academic achievements. Sound amplification using air-conducting hearing aids (HAs) is a common option for hearing rehabilitation of UHL. The processing time of digital HAs can significantly delay the acoustic stimulation in 3 to 10 milliseconds, which is far longer than the maximal natural interaural time difference (ITD) of 750 microseconds. This can further impair spatial localization in these patients. PURPOSE: We sought to assess whether HA effects on ITD and interaural level difference (ILD) impair localization among subjects with unilateral conductive hearing loss (UCHL). RESEARCH DESIGN: "Normal"-hearing participants underwent localization testing in different free field settings. STUDY SAMPLE: Ten volunteers with "normal"-hearing thresholds participated. INTERVENTION: Repeated assessments were compared between "normal" (binaural) hearing, UCHL induced by insertion of an inactivated HA to the ear canal (conductive HL), and amplification with a HA. RESULTS: In UCHL mode, with HA switched-off, localization was significantly impaired compared to "normal" hearing (NH; η2 = 0.151). Localization error was more pronounced when sound was presented from the front and from the side of the occluded ear. When switched-on, amplification with HAs significantly improved localization for all participants compared to UCHL. Better localization with HAs was seen in high frequencies compared to low frequencies (η2 = 0.08, 0.03). Even with HAs, localization did not reach that of NH (η2 = 0.034). CONCLUSIONS: Mild UCHL caused localization to deteriorate. HAs significantly improved sound localization, albeit the delay caused by the device processing time. Most of the improvements were seen in high-frequency sounds, representing a beneficial effect of amplification on ILD. Our results have potential clinical value in situations of mild CHL, for instance, otitis media with effusion.

Efficacy of Oral Steroids for Acute Acoustic Trauma.

OBJECTIVE: This study aimed to study the effect of steroid treatment on new-onset sensorineural hearing loss (SNHL) in subjects presenting shortly after an audiometry-confirmed acute acoustic trauma (AAT) injury. STUDY DESIGN: This is a case-control study. METHODS: We identified healthy military personnel who presented with AAT injury to the Israeli Defense Forces Medical Corps Otolaryngology/Audiology Services during 2016-2020. Patients were nonrandomly allocated to a treatment arm, where they received steroids (prednisone, 1 mg/kg, 60 mg maximal daily dose), administered for either ≥7 days or <7 days, or to a control arm, in which no treatment was offered besides loud noise avoidance. Audiometries were conducted within 7 days following the AAT and within 1 month later. We compared changes in bone conduction (BC) and air conduction (AC) thresholds at 2-8 kHz. RESULTS: Of the 263 enrolled subjects, 137 (52%) received steroids and 126 (48%) received no treatment. Subjects who were treated early (<24 h) with high-dose steroids and for ≥7 days demonstrated significantly better hearing outcomes, compared with the nontreatment group. Subjects in the steroids group demonstrated 13-14 dB average improvement in BC thresholds at 3 and 4 kHz (p = 0.001) and additional 7-8 dB average improvement in AC thresholds at 6 and 8 kHz, compared with the nontreatment group (p < 0.0001). These observations were more compelling in patients who initially presented with worse hearing losses (>35 dB). No statistically significant differences were observed in AC/BC pure tone average between the two groups. CONCLUSIONS: Early oral steroids are recommended in AAT injuries and were shown to improve hearing outcomes within 1 month.

Situational Awareness: The Effect of Stimulus Type and Hearing Protection on Sound Localization.

The purpose of the current study was to test sound localization of a spoken word, rarely studied in the context of localization, compared to pink noise and a gunshot, while taking into account the source position and the effect of different hearing protection devices (HPDs) used by the listener. Ninety participants were divided into three groups using different HPDs. Participants were tested twice, under with- and no-HPD conditions, and were requested to localize the different stimuli that were delivered from one of eight speakers evenly distributed around them (starting from 22.5°). Localization of the word stimulus was more difficult than that of the other stimuli. HPD usage resulted in a larger mean root-mean-square error (RMSE) and increased mirror image reversal errors for all stimuli. In addition, HPD usage increased the mean RMSE and mirror image reversal errors for stimuli delivered from the front and back, more than for stimuli delivered from the left and right. HPDs affect localization, both due to attenuation and to limitation of pinnae cues when using earmuffs. Difficulty localizing the spoken word should be considered when assessing auditory functionality and should be further investigated to include HPDs with different attenuation spectra and levels, and to further types of speech stimuli.

The "Morning Voice": The Effect of 24 Hours of Sleep Deprivation on Vocal Parameters of Young Adults.

Fatigue following sleep deprivation adversely affects various aspects of human performance. It also induces recognizable voice changes, but the literature is inconsistent regarding their nature. The current study used acoustical analyses to assess the effect of 24 hours of sleep deprivation on vocal parameters of young adults. Forty-seven participants (23 females and 24 males) were tested after nocturnal sleep and after 24 hours of sleep deprivation. Different voice samples were recorded (sustained phonation, words, and sentences) and analyzed for fundamental frequency (F0, in Hz), vocal intensity (in dB), harmonic-noise ratio (HNR, in dB), jitter, and shimmer (in %). The main finding was significantly higher HNR values following sleep deprivation than nocturnal sleep for females, across all voice samples. The HNR is a measure of the degree of acoustic periodicity, or the amount of noise compared to the harmonic quality present in the voice. As its values are higher, the voice quality is perceptually better. The current results indicate that females had a significantly higher ratio of vocal harmonics compared to vocal noise when they were sleep deprived. In contrast, following nocturnal sleep, the ratio of vocal harmonics compared to vocal noise was lower, which means the voice quality was poorer. This may explain the common perceptual impressions of decreased voice quality after sleep, which may be more pronounced in females.

Acute Acoustic Trauma among Soldiers during an Intense Combat.

BACKGROUND: During military actions, soldiers are constantly exposed to various forms of potentially harmful noises. Acute acoustic trauma (AAT) results from an impact, unexpected intense noise ≥140 dB, which generates a high-energy sound wave that can damage the auditory system. PURPOSE: We sought to characterize AAT injuries among military personnel during operation "Protective Edge," to analyze the effectiveness of hearing protection devices (HPDs), and to evaluate the benefit of steroid treatment in early-diagnosed AAT injury. RESEARCH DESIGN: We retrospectively identified affected individuals who presented to military medical facilities with solitary or combined AAT injuries within 4 mo following an intense military operation, which was characterized with an abrupt, intensive noise exposure (July-December 2014). STUDY SAMPLE: A total of 186 participants who were referred during and shortly after a military operation with suspected AAT injury. INTERVENTIONS: HPDs, oral steroids. DATA COLLECTION AND ANALYSIS: Data extracted from charts and audiograms included demographics, AAT severity, worn HPDs, first and last audiograms and treatment (if given). The Student's independent samples t test was used to compare continuous variables. All tests were considered significant if p values were ≤0.05. RESULTS: A total of 186 participants presented with hearing complaints attributed to AAT: 122, 39, and 25 were in duty service, career personnel, and reservists, with a mean age of 21.1, 29.2, and 30.4 yr, respectively. Of them, 92 (49%) participants had confirmed hearing loss in at least one ear. Hearing impairment was significantly more common in unprotected participants, when compared with protected participants: 62% (74/119) versus 45% (30/67), p < 0.05. Tinnitus was more common in unprotected participants when compared with protected participants (75% versus 49%, p = 0.04), whereas vertigo was an uncommon symptom (5% versus 2.5%, respectively, p > 0.05). In the 21 participants who received steroid treatment for early-diagnosed AAT, bone-conduction hearing thresholds significantly improved in the posttreatment audiograms, when compared with untreated participants (p < 0.01, for 1-4 kHz). CONCLUSIONS: AAT is a common military injury, and should be diagnosed early to minimize associated morbidity. HPDs were proven to be effective in preventing and minimizing AAT hearing sequelae. Steroid treatment was effective in AAT injury, if initiated within 7 days after noise exposure.

Improving word recognition in noise among hearing-impaired subjects with a single-channel cochlear noise-reduction algorithm.

A common complaint of the hearing impaired is the inability to understand speech in noisy environments even with their hearing assistive devices. Only a few single-channel algorithms have significantly improved speech intelligibility in noise for hearing-impaired listeners. The current study introduces a cochlear noise reduction algorithm. It is based on a cochlear representation of acoustic signals and real-time derivation of a binary speech mask. The contribution of the algorithm for enhancing word recognition in noise was evaluated on a group of 42 normal-hearing subjects, 35 hearing-aid users, 8 cochlear implant recipients, and 14 participants with bimodal devices. Recognition scores of Hebrew monosyllabic words embedded in Gaussian noise at several signal-to-noise ratios (SNRs) were obtained with processed and unprocessed signals. The algorithm was not effective among the normal-hearing participants. However, it yielded a significant improvement in some of the hearing-impaired subjects under different listening conditions. Its most impressive benefit appeared among cochlear implant recipients. More than 20% improvement in recognition score of noisy words was obtained by 12, 16, and 26 hearing-impaired at SNR of 30, 24, and 18 dB, respectively. The algorithm has a potential to improve speech intelligibility in background noise, yet further research is required to improve its performances.

Very low doses of delta 8-THC increase food consumption and alter neurotransmitter levels following weight loss.

We have investigated the effect of 0.001 mg/kg delta(8)-tetrahydrocannabinol (THC) on food consumption, cognitive function, and neurotransmitters in mice. Sabra mice were treated with vehicle, THC, or THC+CB1 antagonist (SR141716A). The mice were fed for 2.5 h a day for 9 or 50 days. In the 9-day schedule, THC-treated mice showed a 16% increase in food intake compared with controls (P<.001). This effect was reversed by the antagonist (P<.01). In the long-term schedule a 22% increase in intake (P<.05) was recorded. During the course of the 9- and 50-day experimental protocol, all mice lost about 20% and 10% of their original weight, respectively, to reach approximately the same weights, which were not significantly different between the different treatment groups. In addition, THC caused an increase in activity (P<.05). Cognitive function showed a tendency to improve (P<.06) in the THC-treated mice, which was reversed by the antagonist for Days 4 and 5 of the maze (P<.01, and P<.05, respectively). Significant decreases in dopamine and serotonin (5-HT) levels were found both in the hypothalamus (P<.01) and the hippocampus (P<.01, P<.05), respectively, while norepinephrine (NE) levels showed tendency to increase in both the hypothalamus and hippocampus. Delta(8)-THC increased food intake significantly more (P<.05) than did delta(9)-THC, while performance and activity were similar. Thus, delta(8)-THC (0.001 mg/kg) caused increased food consumption and tendency to improve cognitive function, without cannabimimetic side effects. Hence, a low dose of THC might be a potential therapeutic agent in the treatment of weight disorders.