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N.M. Gürel

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Master thesis (2025) - O.J. Braakman, N.M. Gürel, J.C. van Gemert, S. Dumančić, S. van Rooij, G. Burghouts
State-of-the-art models are susceptible to adversarial attacks. These attacks can cause catastrophic misclassification when robustness is required. With the increasing popularity of the retrieval augmentation paradigm in deep learning, we adopt it as a fully differential framework for adversarial robustness. We evaluate our method on three visual classification datasets, including ImageNet and attack our model with two white box attacks and a black box attack under various L2 and L norms. The results indicate that a robust classifier emerges if the model fully relies on retrieved examples. We find that we can already obtain a PGD robust ImageNet classifier with 80.1% clean and 64.7% adversarial accuracy, using only one or two examples per class from the training data in the memory set. Contrary to other adversarial defense mechanisms, our method works directly on top of pre-trained models and remains robust when other defenses start to degrade for PGD attacks increasing in strength. ...
Automatic Speech Recognition (ASR) systems are becoming increasingly popular in this day and age. Unfortunately, due to inherent biases within these systems, performance disparities exist among specific demographic groups. Bias metrics can be used to measure this bias. Within ASR they represent a niche area that has not yet been thoroughly explored. The few bias metrics that exist in literature mainly centre around the performance differences between speaker groups. This paper proposes two new bias metrics that focus not only on performance differences, but also take the base performance into account: Weighted Performance Bias (WPB) and Intergroup Weighted Performance Bias (IWPB). Although the lack of ground truth makes the results less easily interpretable, the results show similar trends within the new metrics as those defined in literature: bias is greatest among non-native Dutch speech. ...