The auditory brainstem response (ABR) is a noninvasive test that measures neural activity in response to auditory stimuli. Racial differences in head shape have provided strong evidence for specific normative data and accurate device calibration. International standards emphasize the need for standardized procedures and references. This study aimed to outline the standard procedure and related normative ABR values. Standard procedures were performed according to International Electrotechnical Commission (IEC) standards. Five studies from two countries were included to compare the normative values of the ABR. The dataset from the National Standard Reference Data Center (NSRDC) was used as reference. Normative values were described in terms of stimuli, latency, and amplitude. For click stimuli, the latency of the ABR showed different patterns across populations, such as those from Korea and the USA. Although the latencies reported by the NSRDC and for Koreans were relatively short, those reported for USA populations were longer. Using clicks, it was shown that the USA population had the largest ABR amplitude compared to those reported for the other two datasets. For Wave V latency using tone bursts, a similar pattern was identified with click stimuli. Frequency-specific trends were also observed. Although there is a lack of ABR datasets, the information and insights of the present study could be utilized as standard guidelines in research on ABR.

Background and Objectives: The digits-in-noise (DIN) test was developed as a simple and time-efficient hearing-in-noise test worldwide. The Korean version of the DIN (K-DIN) test was previously validated for both normal-hearing and hearing-impaired listeners. This study aimed to explore the factors influencing the outcomes of the K-DIN test further by analyzing the threshold (representing detection ability) and slope (representing test difficulty) parameters for the psychometric curve fit. Subjects and Methods: In total, 35 young adults with normal hearing participated in the K-DIN test under the following four experimental conditions: 1) background noise (digit-shaped vs. pink noise); 2) gender of the speaker (male vs. female); 3) ear side (right vs. left); and 4) digit presentation levels (55, 65, 75, and 85 dB). The digits were presented using the method of constant stimuli procedure. Participant responses to the stimulus trials were used to fit a psychometric function, and the threshold and slope parameters were estimated according to pre-determined criteria. The accuracy of fit performance was determined using the root-mean-square error calculation. Results: The listener’s digit detection ability (threshold) was slightly better with pink noise than with digit-shaped noise, with similar test difficulties (slopes) across the digits. Gender and the tested ear side influenced neither the detection ability nor the task difficulty. Additionally, lower presentation levels (55 and 65 dB) elicited better thresholds than the higher presentation levels (75 and 85 dB); however, the test difficulty varied slightly across the presentation levels. Conclusions The K-DIN test can be influenced by stimulus factors. Continued research is warranted to understand the accuracy and reliability of the test better, especially for its use as a promising clinical measure.

Background and Objectives: Trendy technologies, such as artificial intelligence, virtual reality (VR), and augmented reality (AR) are being increasingly used for hearing loss, tinnitus, and vestibular disease. Thus, we conducted this systematic review and meta-analysis to identify the possible benefits of the use of VR and AR technologies in patients with hearing loss, tinnitus, and/or vestibular dysfunction, with the aim of suggesting potential applications of these technologies for both researchers and clinicians. Materials and Methods: Published articles from 1968 to 2022 were gathered from six electronic journal databases. Applying our specified inclusion and/or exclusion criteria, 23 studies were analyzed. As only one article on hearing loss and two articles on tinnitus were found, 20 studies on vestibular dysfunction were only finally included for the meta-analysis. Standardized mean differences (SMDs) were chosen as estimates to compare the studies. A funnel plot and Egger’s regression analysis were used to identify any risk of bias. Results: High heterogeneity (I2: 83%, τ2: 0.5431, p<0.01) was identified across the studies on vestibular dysfunction. VR-based rehabilitation was significantly effective for individuals with vestibular disease (SMDs: 0.03, 95% confidence interval [CI]: -0.08 to 0.15, p<0.05). A subgroup analysis revealed that only improvement in the subjective questionnaire was meaningful and statistically significant (SMDs: -0.66, 95% CI: -1.10 to -0.22). Conclusions VR-based vestibular rehabilitation showed potential for subjective rating measures like Dizziness Handicap Index. The negative effect of aging on vestibular disease was indirectly confirmed. More clinical trials and an evidence-based approach are needed to confirm the implementation of state-of-the-art technology for hearing loss and tinnitus, representative diseases in neurotology.

Background and Objectives: Although the digit-in-noise (DIN) test is simple and quick, little is known about its key factors. This study explored the considerable components of the DIN test through a systematic review and meta-analysis. Materials and Methods: After six electronic journal databases were screened, 14 studies were selected. For the meta-analysis, standardized mean difference was used to calculate effect sizes and 95% confidence intervals. Results: The overall result of the meta-analysis showed an effect size of 2.224. In a subgroup analysis, the patient’s hearing status was found to have the highest effect size, meaning that the DIN test was significantly sensitive to screen for hearing loss. In terms of the length of the presenting digits, triple digits had lower speech recognition thresholds (SRTs) than single or pairs of digits. Among the types of background noise, speech-spectrum noise provided lower SRTs than multi-talker babbling. Regarding language variance, the DIN test showed better performance in the patient’s native language(s) than in other languages. Conclusions When uniformly developed and well validated, the DIN test can be a universal tool for hearing screening.

Background and Objectives: Natural and synthetic speech signals effectively stimulate cortical auditory evoked potential (CAEP). This study aimed to select the speech materials for CAEP and identify CAEP waveforms according to gender of speaker (GS) and gender of listener (GL). Subjects and Methods: Two experiments including a comparison of natural and synthetic stimuli and CAEP measurement were performed of 21 young announcers and 40 young adults. Plosive /g/ and /b/ and aspirated plosive /k/ and /p/ were combined to /a/. Six bisyllables–/ga/-/ka/, /ga/-/ba/, /ga/-/pa/, /ka/-/ba/, /ka/-/pa/, and /ba/-/pa/–were formulated as tentative forwarding and backwarding orders. In the natural and synthetic stimulation mode (SM) according to GS, /ka/ and /pa/ were selected through the first experiment used for CAEP measurement. Results: The correction rate differences were largest (74%) at /ka/-/ pa/ and /pa/-/ka/; thus, they were selected as stimulation materals for CAEP measurement. The SM showed shorter latency with P2 and N1-P2 with natural stimulation and N2 with synthetic stimulation. The P2 amplitude was larger with natural stimulation. The SD showed significantly larger amplitude for P2 and N1-P2 with /pa/. The GS showed shorter latency for P2, N2, and N1-P2 and larger amplitude for N2 with female speakers. The GL showed shorter latency for N2 and N1-P2 and larger amplitude for N2 with female listeners. Conclusions Although several variables showed significance for N2, P2, and N1-P2, P1 and N1 did not show any significance for any variables. N2 and P2 of CAEP seemed affected by endogenous factors.

The present study aimed to compare thresholds of directbone-conduction (BC direct) with those of behaviorally measured BC pure-tone audiometry(PTA) and objectively measured BC auditory brainstem response (ABR) to confirm the clinicalfeasibility of their relationships. Subjects and Methods: Young adults with normal hearingparticipated in the study to determine the thresholds from three measurements at four testingfrequencies. In the BC direct, the vibrator of a bone-anchored hearing aid softband wasplaced on the right mastoid of each subject. In both PTA and ABR, a B71 bone oscillatorwas placed on the subject’s right mastoid. While the subject’s thresholds of BC direct andBC PTA were determined with a clinically routine 5-dB step procedure, BC ABR was conductedto determine the individual’s hearing sensitivity by a peak V of the waveform usingtone-burst and click stimuli. Results: The BC direct showed a different pattern between lowand high frequencies. Precisely, its thresholds were 13.25 and 12.25 dB HL at 0.5 and 1kHz, respectively, but 19 and 19.75 dB HL at 2 and 4 kHz, respectively. A significant positivecorrelation existed between BC direct and PTA at 1 kHz, which was also correlated withABR. Conclusions: Based on the current data, the thresholds of BC direct were similar toBC PTA at low frequencies and BC ABR at high frequencies. The thresholds of BC directmight be predictable at approximately 5 dB higher (or lower) than that in PTA, although alarge data set is required for standardization. J Audiol Otol 2020;24(2):85-90

Auditory scene analysis is defined as a listener’s ability to segregate a meaningful message from meaningless background noise in a listening environment. To gain better understanding of auditory perception in terms of message integration and segregation ability among concurrent signals, we aimed to systematically review the size of auditory scenes among individuals. A total of seven electronic databases were searched from 2000 to the present with related key terms. Using our inclusion criteria, 4,507 articles were classified according to four sequential steps–identification, screening, eligibility, included. Following study selection, the quality of four included articles was evaluated using the CAMARADES checklist. In general, studies concluded that the size of auditory scene increased as the number of sound sources increased; however, when the number of sources was five or higher, the listener’s auditory scene analysis reached its maximum capability. Unfortunately, the score of study quality was not determined to be very high, and the number of articles used to calculate mean effect size and statistical significance was insufficient to draw significant conclusions. We suggest that study design and materials that consider realistic listening environments should be used in further studies to deep understand the nature of auditory scene analysis within various groups.

Background and Objectives: In distracting listening conditions, individuals need to pay extra attention to selectively listen to the target sounds. To investigate the amount of listening effort required in reverberating and noisy backgrounds, a semantic mismatch was examined. Subjects and Methods: Electroencephalography was performed in 18 voluntary healthy participants using a 64-channel system to obtain N400 latencies. They were asked to listen to sounds and see letters in 2 reverberated×2 noisy paradigms (i.e., Q-0 ms, Q-2000 ms, 3 dB-0 ms, and 3 dB-2000 ms). With auditory-visual pairings, the participants were required to answer whether the auditory primes and letter targets did or did not match. Results: Q-0 ms revealed the shortest N400 latency, whereas the latency was significantly increased at 3 dB-2000 ms. Further, Q-2000 ms showed approximately a 47 ms delayed latency compared to 3 dB-0 ms. Interestingly, the presence of reverberation significantly increased N400 latencies. Under the distracting conditions, both noise and reverberation involved stronger frontal activation. Conclusions The current distracting listening conditions could interrupt the semantic mismatch processing in the brain. The presence of reverberation, specifically a 2000 ms delay, necessitates additional mental effort, as evidenced in the delayed N400 latency and the involvement of the frontal sources in this study.

BACKGROUND AND OBJECTIVES: Many studies have reported no benefit of sound localization, but improved speech understanding in noise after treating patients with single-sided deafness (SSD). Furthermore, their performances provided a large individual difference. The present study aimed to measure the ability of speech perception and gap detection in noise for the SSD patients to better understand their hearing nature.
Deafness ; Hearing ; Hearing Loss ; Hearing Loss, Conductive ; Humans ; Individuality ; Noise ; Plastics ; Sample Size ; Signal-To-Noise Ratio ; Silver Sulfadiazine ; Sound Localization ; Speech Perception ; Young Adult

Since noise-induced hearing loss (NIHL) is one of prevalent issues in the occupational settings, hearing protection device (HPD) has been widely used to reduce noise exposure levels and to prevent developing NIHL. This review study aimed to introduce several types of the HPD in terms of current trends, its variety and functions, and application. Including a brief history of the HPD, we explain its two types, i.e., passive and active functions, in the first part of main body. The passive HPD has a flat attenuation across the overall frequency range, whereas the active HPD effectively preserves communication components such as meaningful speech with low intensity stimuli while filtering out the high levels of noise. In the second part of the main body, we discuss some negative issues of hearing functions when users are wearing the HPD. In detail, the active HPD does not much degrade the hearing performance for speech detection/recognition and sound source localization compared to the passive HPD. Rather, reduced sound (or music) quality is improved with active one in general. In the final part, we mention that although various applications in the special fields such as factory, mining, army, airplane, and music have been demonstrated, the usage and awareness of HPD in occupational aspect may not follow its fast technological development. Furthermore, most people do not know about either importance or use method of HPD in the non-occupational setting. For these reasons, we conclude that hearing professionals have to access the latest trends of the HPD and to increase their knowledge on it, and thus they should provide the best HPD prescription for the public as well as employees who have to protect their ears from hazard noise impacts.
Aircraft ; Ear ; Hearing Loss, Noise-Induced ; Hearing* ; Methods ; Mining ; Music ; Noise ; Prescriptions ; Public Health