The goal of the present study was to investigate the human factors issues related to acoustic beacons used for auditory navigation. Specific issues addressed were: (1) the effect of various beacon characteristics on human accuracy in turning toward the direction of the acoustic beacon; (2) the difference between real and virtual environments on human accuracy in turning toward the acoustic beacon; and (3) the perceived sound quality of various acoustic beacons. Three experiments were conducted in which acoustic beacons were presented in a background of 80 dBA pink noise. Results of the localization tasks revealed that (a) presentation mode (continuous versus pulsed beacon sound) did not affect the overall localization accuracy or number of front-back confusion errors; and (b) the type of acoustic beacon affected the size of localization error. Results of the sound quality assessment indicated that listeners had definite preferences regarding the type of sound being used as a beacon, with (a) non-speech beacons preferred over speech beacons, (b) a beacon repetition rate of 1.1 rps preferred over either the 0.7 or 2.5 rps rates, and (c) a continuous operation of a beacon preferred over a pulsed operation. Finally, sound quality ratings and localization errors were highly negatively correlated. This finding demonstrates the usefulness and practical values of sound quality judgements for audio display design and evaluation.

Background The central nervous system integrates information from different sensory inputs (vestibular, visual, and somatosensory) to maintain balance. However, strategies for weighing sensory information change as maturation occurs. Purpose The purpose of this study was to: (1) evaluate postural control development in a large sample of healthy children aged 5 to 17 years old, (2) analyze changes in sensory weighting strategies as maturation occurs, and (3) determine the extent to which anthropometric characteristics (height, weight, body mass index [BMI]) influence postural control. Sample Size This study recruited 120 healthy children, equally distributed in gender and number, into four age groups (5–8 years, 9–11 years, 12–14 years, and 15–17 years) and compared them to a control group of 20 healthy adults (aged 20–25 years). Research Design The sensory organization test (SOT) was used to assess overall balance and the use of specific sensory inputs to maintain postural control. All children underwent the six SOT conditions: (1) eyes open, surround and platform stable, (2) eyes closed, surround and platform stable, (3) eyes open, sway-referenced surround, platform stable, (4) eyes open, sway-referenced platform, (5) eyes closed, sway-referenced platform, and (6) eyes open, sway-referenced surround and platform. Data Analysis Condition-specific equilibrium scores (ES), composite equilibrium scores (CES), and sensory analysis ratios were analyzed to determine whether the performance was related to age, gender, or specific anthropometric characteristics (height, weight, and BMI). Results Data showed a significant age-associated improvement in ES for all 6 conditions (p < 0.05) and in CES (p = 0.001). For both genders, (1) somatosensory function was adult-like by age 5 to 8 years, (2) visual function peaked around age 12 years, and (3) vestibular function reached maturity by age 15 to 17 years (p < 0.05). A moderate positive correlation (r(140) = 0.684, p = 0.01; two-tailed) between height and CES was found and a weak positive correlation (r(140) = 0.198, p = 0.01) between height and somatosensory ratio was noted. Lower vestibular ratio scores were observed in children who had a higher BMI (p = 0.001). Conclusion The efficient use of individual sensory system input to maintain balance does not occur at the same age. Age and gender affect the changes in sensory weighting strategies, while height and BMI influence postural control in children. These factors need to be accounted for in child assessment.

Pure-tone audiometry is not always appropriate with young children and with difficult to test populations. In such cases, various other audiological tests that are based on broadband sound effect detection and recognition tasks are used. However, results of those tests do not provide frequency specific information about the client’s hearing. The purpose of the present study was to determine whether selected sound effects that are spectrally limited to 1 octave bandwidth could be used as a basis for frequency-specific environmental audiometry. Twenty adults with normal hearing sensitivity participated in the study. Their task was to detect and recognize various bandlimited musical and environmental sounds presented in quiet and noise. The results of the study indicate that environmental audiometry based on filtered sound effects is a promising alternative to pure-tone audiometry. Further studies with children and the development of normalized thresholds using frequency-specific sound effects are needed.

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Detection of the target signal deteriorated as background noise level increased and was dependent on the source location of the incoming signal, as expected. Localization accuracy of the target signal was highly dependent on the SNR and spatial location of the signal source. Detection and localization accuracy data were found to be repeatable across test sessions and response patterns were found to be symmetrical on the right and left sides of the horizontal plane.

This study assessed the effects of spatialized sound presentation on a listener's ability to monitor target (T) messages in the presence of competing (C) messages and high-level (110 dB[A]) background noise (BGN). In a simulated military environment, 8 participants wore two-channel, active noise reduction (ANR) equipped helmets and listened to combinations of T and C messages (89 dB[A] at the ear). T messages were presented synchronously with 0, 1, 2, and 3 C messages in four listening modes: (a) BGN + diotic, (b) BGN + dichotic, (c) BGN + spatial audio, and (d) quiet + spatial audio. Best overall performance occurred in the spatialized modes (c and d) and poorest in the diotic mode (a). As expected, speech recognition was better in quiet than in BGN when multiple C messages were present. Findings indicate that message spatialization in acoustic space improves auditory performance during times of heavy message competition, even in high-level noise. The proposed technology has numerous applications, such as multichannel communications in tactical operations centers, monitoring of complex security systems, and air traffic control.

Although TEOAE responses were measurable in all singers with normal audiometric thresholds, responses were less robust than those of NH-Cs. The findings suggest that subtle cochlear dysfunction can be detected with TEOAE measurement in a subset of normal-hearing professional singers. Although preliminary, the study findings highlight the importance of pass or fail criterion choice on the number of ears that will be identified as "at risk" for music-induced hearing loss.

Background Pediatric oculomotor function can be evaluated via videonystagmography. Adult normative data for saccades and smooth pursuit tests cannot be used as a benchmark for pediatric patients because children's peripheral and central systems continue to mature throughout adolescence. Purpose The purpose of this study was to establish normative data for saccade and smooth pursuit tests that can be used clinically in the assessment of vestibular and neurological disorders in children, and to investigate the effect of age and eye movement direction (left/right) on tests parameters. Research Design The present study is prospective cross-sectional study. Study Sample A total of 120 healthy children were recruited and equally distributed according to age and gender to each of the following groups: 5-8, 9-11, 12-14, and 15-17 years old. Participants had to pass a comprehensive otological and neurological assessment prior to inclusion in the study. Each subject underwent saccade and smooth pursuit testing. Data Collection and Analysis Saccade latency, velocity and accuracy/precision, and smooth pursuit gain were analyzed across groups using a two-way repeated measure multivariate analysis of variance (MANOVA). Results Saccadic latency was longer in the youngest group aged 5-8 years old (305 ± 48 msec) in comparison to children aged 9-11 years old (276 ± 22 msec) (P = 0.017), 12-14 years old (252 ± 34 msec) (P = 0.001) adolescents 15-17 years (256 ± 33 msec) (P = 0.001). Age did not affect the results of saccadic velocity and accuracy/precision. Saccade parameters (latency, velocity, accuracy/ precision) were not affected by oculomotor direction (left vs. right). Smooth pursuit gain increased from 0.63 in children aged 5-8 years old to 0.85 in children aged 15-17 years (P = 0.0001). The percentage of gain asymmetry was significantly different in the youngest two groups. Conclusion Saccade latency decreased as age increased. Smooth pursuit gains increased with increased age. Saccade velocity and accuracy/precision did not change significantly from ages 5-8 to 15-17 years of age. These data provide normative values for pediatric oculomotor evaluation and suggest that saccade and pursuit pathways may mature at different rates.