Two-microphone spatial filtering provides speech reception benefits for cochlear implant users in difficult acoustic environments

Abstract

This article introduces and provides an assessment of a spatial-filtering algorithm based on two closely-spaced ($1 cm) microphones in a behind-the-ear shell. The evaluated spatial-filtering algorithm used fast ($10 ms) temporal-spectral analysis to determine the location of incoming sounds and to enhance sounds arriving from straight ahead of the listener. Speech reception thresholds (SRTs) were measured for eight cochlear implant (CI) users using consonant and vowel materials under three processing conditions: An omni-directional response, a dipole-directional response, and the spatial-filtering algorithm. The background noise condition used three simultaneous time-reversed speech signals as interferers located at 90 , 180 , and 270. Results indicated that the spatial-filtering algorithm can provide speech reception benefits of 5.8 to 10.7 dB SRT compared to an omni-directional response in a reverberant room with multiple noise sources. Given the observed SRT benefits, coupled with an efficient design, the proposed algorithm is promising as a CI noise-reduction solution.

ForwardFocus with cochlear implant recipients in spatially separated and fluctuating competing signals – introduction of a reference metric

“…Using a coherence-based spatial filter, Yousefian and Loizou (2011) were able to demonstrate significant improvements in some listening conditions compared to a fixed directional microphone and suggested its suitability for CI sound processors. Another spatial post-filtering algorithm based on phase-differences has also demonstrated improved performance compared to omnidirectional and dipole directional microphones in a spatial noise environment (Goldsworthy et al 2014). A subsequent study using the spatial post-filter algorithm investigated performance in a range of reverberant environments and with a range of noise sources showing benefit in reverberant and complex multiple noise source environments (Goldsworthy 2014).…”

Speech acquisition in noisy environments using dual microphone arrays

“…Простейшими МР являются двухэлементные решетки (МР2). Рассматриваемые МР2 состоят из двух ненаправленных микрофонов, разнесенных на расстояние d. Благодаря простоте и компактности МР2 нашли применение в решении различных задач, в том числе для подавления реверберации и шума в системах дистанционного распознавания речи [1][2][3][4]. В настоящее время выпускаются как сами МР2, так и схемы для обработки сигналов МР2 1,2,3,4 .…”

“…Dual Input, Far Field Noise Suppression Microphone Amplifier. System Description // Texas Instruments, 2013 3. https://www.synaptics.com//CX20921 -Two-Microphone Far-Field Voice DSP Processor SoC 4.…”

Two-Microphone Spatial Filtering Improves Speech Reception for Cochlear-Implant Users in Reverberant Conditions With Multiple Noise Sources

“… Goldsworthy, Delhorne, Desloge, and Braida (2014) transitioned the binaurally inspired spatial filtering of Kollmeier to an algorithm based on closely spaced microphones. They demonstrated that phase-based spatial filtering using microphones situated 1 cm apart in a behind-the-ear capsule could provide speech reception benefits between 6 and 11 dB SRT compared with an omnidirectional response when tested in a moderately reverberant environment ( T 60 = 350 ms).…”

“…The spatial-filtering algorithm introduced by Goldsworthy et al. (2014) has demonstrated a degree of robustness in reverberation.…”