Henry Chacón

Henry D. Chacon, Paul Rad

The input space complexity determines the model's capabilities to extract their knowledge and translate the space of attributes into a function which is assumed in general, as a concatenation of non-linear functions between layers. In the presence of backdoor attacks, the space complexity changes, and induces similarities between classes that directly affect the model's training. As a consequence, the model tends to overfit the input set. In this research, we suggest the D-vine Copula Auto-Encoder (VCAE) as a tool to estimate the latent space distribution under the presence of backdoor triggers. Since no assumptions are made on the distribution estimation, like in Variational Autoencoders (VAE). It is possible to observe the backdoor stamp in non-attacked categories randomly generated. We exhibit the differences between a clean model (baseline) and the attacked one (backdoor) in a pairwise representation of the distribution. The idea is to illustrate the dependency structure change in the input space induced by backdoor features. Finally, we quantify the entropy's changes and the Kullback-Leibler divergence between models. In our results, we found the entropy in the latent space increases by around 27\% due to the backdoor trigger added to the input

Arun Das, Jeffrey Mock, Henry Chacon et al.

Speech disorders such as stuttering disrupt the normal fluency of speech by involuntary repetitions, prolongations and blocking of sounds and syllables. In addition to these disruptions to speech fluency, most adults who stutter (AWS) also experience numerous observable secondary behaviors before, during, and after a stuttering moment, often involving the facial muscles. Recent studies have explored automatic detection of stuttering using Artificial Intelligence (AI) based algorithm from respiratory rate, audio, etc. during speech utterance. However, most methods require controlled environments and/or invasive wearable sensors, and are unable explain why a decision (fluent vs stuttered) was made. We hypothesize that pre-speech facial activity in AWS, which can be captured non-invasively, contains enough information to accurately classify the upcoming utterance as either fluent or stuttered. Towards this end, this paper proposes a novel explainable AI (XAI) assisted convolutional neural network (CNN) classifier to predict near future stuttering by learning temporal facial muscle movement patterns of AWS and explains the important facial muscles and actions involved. Statistical analyses reveal significantly high prevalence of cheek muscles (p<0.005) and lip muscles (p<0.005) to predict stuttering and shows a behavior conducive of arousal and anticipation to speak. The temporal study of these upper and lower facial muscles may facilitate early detection of stuttering, promote automated assessment of stuttering and have application in behavioral therapies by providing automatic non-invasive feedback in realtime.