Head and Eye Movements Reveal Compensatory Strategies for Acute Binaural Deficits During Sound Localization.

The present study aimed to define use of head and eye movements during sound localization in children and adults to: (1) assess effects of stationary versus moving sound and (2) define effects of binaural cues degraded through acute monaural ear plugging. Thirty-three youth (MAge = 12.9 years) and seventeen adults (MAge = 24.6 years) with typical hearing were recruited and asked to localize white noise anywhere within a horizontal arc from -60° (left) to +60° (right) azimuth in two conditions (typical binaural and right ear plugged). In each trial, sound was presented at an initial stationary position (L1) and then while moving at ∼4°/s until reaching a second position (L2). Sound moved in five conditions (±40°, ±20°, or 0°). Participants adjusted a laser pointer to indicate L1 and L2 positions. Unrestricted head and eye movements were collected with gyroscopic sensors on the head and eye-tracking glasses, respectively. Results confirmed that accurate sound localization of both stationary and moving sound is disrupted by acute monaural ear plugging. Eye movements preceded head movements for sound localization in normal binaural listening and head movements were larger than eye movements during monaural plugging. Head movements favored the unplugged left ear when stationary sounds were presented in the right hemifield and during sound motion in both hemifields regardless of the movement direction. Disrupted binaural cues have greater effects on localization of moving than stationary sound. Head movements reveal preferential use of the better-hearing ear and relatively stable eye positions likely reflect normal vestibular-ocular reflexes.

Pediatric nasopharyngeal airways expand when exposed to saline.

PURPOSE: Nasopharyngeal airways (NPA) are commonly used to relieve upper airway obstruction in children. They must be sized to extend posterior to the tongue base but remain above the epiglottis. To avoid obstruction from nasal secretions, frequent irrigation with saline is required. We hypothesized that NPAs would swell when exposed to saline irrigation. METHODS: Twenty-five green Rusch NPA size 12, 14, 16, 18 and 20 Fr were submerged in 2 L of normal saline for 15 days. Tube length, inner diameter, outer diameter and wall thickness were measured on days 1,2,3,4,5,10, and 15 and compared using two-way repeated measures ANOVA and paired t-tests with Bonferroni correction. RESULTS: All dimensions increased significantly with exposure to saline. Increases in length, inner diameter, outer diameter and wall thickness were dependent on original tube size (p < 0.05) and duration of exposure to saline (p < 0.001). The increase in tube length was greatest over the first five days. CONCLUSION: NPAs expand significantly when exposed to saline with the greatest increase in length occurring in the first five days. This could lead to gagging or airway obstruction in small children. Patients with NPAs should be monitored closely for these signs and new materials should be sourced to prevent these issues.

Binaural hearing is impaired in children with hearing loss who use bilateral hearing aids.

This paper asked whether children fitted with bilateral hearing aids (BHA) develop normal perception of binaural cues which are the basis of spatial hearing. Data from children with BHA (n = 26, age = 12.6 ± 2.84 years) were compared to data from a control group (n = 12, age = 12.36 ± 2.83 years). Stimuli were 250 Hz click-trains of 36 ms and a 40 ms consonant-vowel /da/ at 1 Hz presented through ER3A insert-earphones unilaterally or bilaterally. Bilateral stimuli were presented at different interaural level difference (ILD) and interaural timing difference (ITD) conditions. Participants indicated whether the sound came from the left or right side (lateralization) or whether one sound or two could be heard (binaural fusion). BHA children lateralized ILDs similarly to the control group but had impaired lateralization of ITDs. Longer response times relative to controls suggest that lateralization of ITDs was challenging for children with BHA. Most, but not all, of the BHA group were able to fuse click and speech sounds similarly to controls. Those unable to fuse showed particularly poor ITD lateralization. Results suggest that ITD perception is abnormal in children using BHAs, suggesting persistent effects of hearing loss that are not remediated by present clinical rehabilitation protocols.