The effects of child language development on the performance of automatic speech recognition

In comparison to adults’, children’s ASR appears to be more challenging and yields inferior results. It has been suggested that for this issue to be addressed, linguistic understanding of children’s speech development needs to be employed to either provide a solution or an explanation. The present work aims to explore the influence of phonological effects associated with language acquisition (PEALA) in children’s ASR and investigate whether they can be detected in systematic patterns of ASR phone confusion errors or they can be evidenced in systematic patterns of acoustic feature structure. Findings from speech development research are used as the framework upon which a set of predictable error patterns is defined and guides the analysis of the experimental results reported. Several ASR experiments are conducted involving both children’s and adults’ speech. ASR phone confusion matrices are extracted and analysed according to a statistical significance test, proposed for the purposes of this work. A mathematical model is introduced to interpret the emerging results. Additionally, bottleneck features and i-vectors representing the acoustic features in one of the systems developed, are extracted and visualised using linear discriminant analysis (LDA). A qualitative analysis is conducted with reference to patterns that can be predicted through PEALA

Incandescent Bulb and LED Brake Lights:Novel Analysis of Reaction Times

Rear-end collision accounts for around 8% of all vehicle crashes in the UK, with the failure to notice or react to a brake light signal being a major contributory cause. Meanwhile traditional incandescent brake light bulbs on vehicles are increasingly being replaced by a profusion of designs featuring LEDs. In this paper, we investigate the efficacy of brake light design using a novel approach to recording subject reaction times in a simulation setting using physical brake light assemblies. The reaction times of 22 subjects were measured for ten pairs of LED and incandescent bulb brake lights. Three events were investigated for each subject, namely the latency of brake light activation to accelerator release (BrakeAcc), the latency of accelerator release to brake pedal depression (AccPdl), and the cumulative time from light activation to brake pedal depression (BrakePdl). To our knowledge, this is the first study in which reaction times have been split into BrakeAcc and AccPdl. Results indicate that the two brake lights containing incandescent bulbs led to significantly slower reaction times compared to eight tested LED lights. BrakeAcc results also show that experienced subjects were quicker to respond to the activation of brake lights by releasing the accelerator pedal. Interestingly, analysis also revealed that the type of brake light influenced the AccPdl time, although experienced subjects did not always act quicker than inexperienced subjects. Overall, the study found that different designs of brake light can significantly influence driver response times

Auricular vagus nerve stimulation for stress reduction: Evidence from alpha prefrontal asymmetry

This study explores auricular vagus nerve stimulation (aVNS) within the context of stress. Five healthy subjects underwent a pulsed mode aVNS (with a frequency of 25 Hz and pulse width of 200 μs) using a custom made current stimulation device. The device triggered the auricular vagus nerve branch through the tragus for 15 minutes, with prefrontal EEG data collected pre and post aVNS (each for 5 minutes) to capture stress indicators. Given that the frontal location is prone to noise, EEG signal pre-processing through independent component analysis (ICA) was used to reduce eye movements and other artifacts. Alpha (8-14 Hz) asymmetry in prefrontal location in both hemispheres was computed from locations Fp1 and Fp2 for one second segments of EEG; these asymmetry values were normalised by subtracting the post aVNS (or placebo) from pre aVNS (placebo). The normalised alpha frontal asymmetries were assessed for statistical significance using T-test. Results showed increased aVNS alpha prefrontal asymmetry compared to placebo, indicating reduced stress. This was statistically significant ( ) for all five subjects. It is therefore concluded that the pulsed mode aVNS stimulation at the tragus may represent a potential approach for stress relief