Vocoder simulations of highly focused cochlear stimulation with limited dynamic range and discriminable steps.

OBJECTIVES: There is recent interest in focused stimulation of the cochlea via modalities such as tripolar electrical and infrared neural stimulation to improve speech in noise comprehension and music perception. The purpose of this work was to use vocoder-based simulations to investigate speech recognition for broad stimulation (standard monopolar paradigm) versus more focused stimulation under a variety of signal-to-noise ratios, dynamic ranges, and numbers of discriminable loudness steps. DESIGN: Vocoder simulations were used to assess the intelligibility of sentences, consonants, and vowels that were noise vocoded and presented to 7 normal-hearing listeners for identification. A novel aspect of the simulations presented here was the use of nonuniform quantization steps within the dynamic range to more closely simulate the Weber functions observed in cochlear implant users. Intelligibility was assessed for the different filter slopes under a variety of signal-to-noise ratio levels, dynamic ranges, and numbers of discriminable steps. RESULTS: Speech processed via vocoder simulations representing focused stimulation was found to be substantially more intelligible than speech processed via a monopolar electric vocoder simulation, with differences of up to 60 percentage points. There were no significant differences, however, seen between the two focused approaches (signal attenuations of 10 and 17 dB/mm) for the conditions investigated. Speech processed via the highly focused vocoder (17 dB/mm) was robust to constraints on small envelope dynamic range and small number of discriminable steps within the dynamic range, as high performance was maintained with at least a 5 dB dynamic range and eight or more discriminable steps. Significant drops in intelligibility were noted when the number of steps fell below eight. CONCLUSIONS: Highly focused stimulation-tripolar electrical and infrared neural stimulation-has potential for increased performance in noise compared with monopolar stimulation, but much work remains to bear this potential out and to take full advantage of each modality's strengths.

Clinical validation of an open-access SARS-COV-2 antigen detection lateral flow assay, compared to commercially available assays.

Rapid tests for SARS-COV-2 infection are important tools for pandemic control, but current rapid tests are based on proprietary designs and reagents. We report clinical validation results of an open-access lateral flow assay (OA-LFA) design using commercially available materials and reagents, along with RT-qPCR and commercially available comparators (BinaxNOW® and Sofia®). Adult patients with suspected COVID-19 based on clinical signs and symptoms, and with symptoms ≤7 days duration, underwent anterior nares (AN) sampling for the OA-LFA, Sofia®, BinaxNOW ™, and RT-qPCR, along with nasopharyngeal (NP) RT-qPCR. Results indicate a positive predictive agreement with NP sampling as 69% (60% -78%) OA-LFA, 74% (64% - 82%) Sofia®, and 82% (73% - 88%) BinaxNOW™. The implication for these results is that we provide an open-access LFA design that meets the minimum WHO target product profile for a rapid test, that virtually any diagnostic manufacturer could produce.