Evaluating Spatial Hearing Using a Dual-Task Approach in a Virtual-Acoustics Environment

Assessing behavioral and neural correlates of change detection in spatialized acoustic scenes

The ability to detect changes in complex auditory scenes is crucial for human survival, yet the neural mechanisms underlying this process remain elusive. This study investigates how the presence and location of sound sources impacts active auditory change detection as well as neural correlates of passive change detection. Stimuli were naturalistic temporal envelopes applied to synthesized broadband carriers designed to eliminate semantics and minimize contextual information while preserving naturalistic temporal envelopes and broadband spectra, presented in a spatial loudspeaker array. Behavioral change detection experiments tasked participants with detecting new sources added to spatialized and non-spatialized multi-source auditory scenes. In a passive listening experiment, participants were given a visual decoy task while neural data were collected via electroencephalography (EEG) during exposure to unattended spatialized scenes and added sources. Our two behavioral experiments (N = 21 and 21) demonstrated that spatializing sounds facilitated change detection compared to non-spatialized presentation, but that performance declined with increasing number of sound sources and higher hearing thresholds at mid-high frequencies, exclusively in spatialized conditions. Slower reaction times were also observed when changes occurred from above or behind the listener, exacerbated by a higher number of sources. Two EEG experiments (N = 32 and 30), using the same stimuli, showed robust change-evoked responses. However, no significant differences were detected in our analysis as a function of spatial location of the appearing source. These findings provide fresh insights into the mechanisms of spatial auditory change detection, emphasizing the dynamic interplay of spatial cues, change location, and scene complexity.

Virtual reality games for spatial hearing training in children and young people with bilateral cochlear implants: the "Both Ears (BEARS)" approach

Spatial hearing relies on the encoding of perceptual sound location cues in space. It is critical for communicating in background noise, and understanding where sounds are coming from (sound localization). Although there are some monoaural spatial hearing cues (i.e., from one ear), most of our spatial hearing skills require binaural hearing (i.e., from two ears). Cochlear implants (CIs) are often the most appropriate rehabilitation for individuals with severe-to-profound hearing loss, with those aged 18 years of age and younger typically receiving bilateral implants (one in each ear). As experience with bilateral hearing increases, individuals tend to improve their spatial hearing skills. Extensive research demonstrates that training can enhance sound localization, speech understanding in noise, and music perception. The BEARS (Both Ears) approach utilizes Virtual Reality (VR) games specifically designed for young people with bilateral CIs to train and improve spatial hearing skills. This paper outlines the BEARS approach by: (i) emphasizing the need for more robust and engaging rehabilitation techniques, (ii) presenting the BEARS logic model that underpins the intervention, and (iii) detailing the assessment tools that will be employed in a clinical trial to evaluate the effectiveness of BEARS in alignment with the logic model.

Speech discrimination and word identification with a consumer-level bone-conduction headset and remote microphone for children with normal hearing

OBJECTIVE

This study investigated the use of bone-conduction headsets paired to a wireless, remote microphone on speech discrimination and word identification for children with normal hearing.

DESIGN

Children were tested with and without the headset, using the McCormick speech discrimination test in quiet and in speech-shaped noise to measure word-discrimination thresholds. Additionally, open-set word identification in noise was assessed while children were simultaneously engaged in a visual-monitoring task.

STUDY SAMPLE

Twenty normal-hearing children, aged 4-11 years.

RESULTS

Median word-discrimination threshold in quiet (n = 20) was 20.5 dB(A) without a headset and 11.5 dB(A) with a headset (Z = -3.826, p = 0.0001). In noise, the median word-discrimination threshold (n = 20) was 52 dB(A) without a headset and 40.5 dB(A) with a headset (Z = -3.926, p< 0.0001). For open-set word identification (n = 11), children performed significantly better with a headset than without it, with an average improvement of 23 percentage points (t(10) = -5.227, p = 0.0004, two tailed).

CONCLUSIONS

A bone-conduction headset paired to a Bluetooth microphone improved discrimination of distant speech in quiet and in noise and open-set word identification in noise.