Dissertation Defense: Phani Nidadavolu
Note: This is a virtual presentation. Here is the link for where the presentation will be taking place.
Title: Unsupervised Domain Adaptation for Speaker Verification in the Wild
Abstract: Performance of automatic speaker verification (ASV) systems is very sensitive to mismatch between training (source) and testing (target) domains. The best way to address domain mismatch is to perform matched condition training – gather sufficient labeled samples from the target domain and use them in training. However, in many cases this is too expensive or impractical. Usually, gaining access to unlabeled target domain data, e.g., from open source online media, and labeled data from other domains is more feasible. This work focuses on making ASV systems robust to uncontrolled (‘wild’) conditions, with the help of some unlabeled data acquired from such conditions.
Given acoustic features from both domains, we propose learning a mapping function – a deep convolutional neural network (CNN) with an encoder-decoder architecture – between features of both the domains. We explore training the network in two different scenarios: training on paired speech samples from both domains and training on unpaired data. In the former case, where the paired data is usually obtained via simulation, the CNN is treated as a non-linear regression function and is trained to minimize L2 loss between original and predicted features from target domain. Though effective, we provide empirical evidence that this approach introduces distortions that affect verification performance. To address this, we explore training the CNN using adversarial loss (along with L2), which makes the predicted features indistinguishable from the original ones, and thus, improve verification performance.
The above framework, though effective, cannot be used to train the network on unpaired data obtained by independently sampling speech from both domains. In this case, we first train a CNN using adversarial loss to map features from source to target. We, then, map the predicted features back to the source domain using an auxiliary network, and minimize a cycle-consistency loss between the original and reconstructed source features.
To prevent the CNN from over-fitting when trained on limited amounts of data, we present a simple regularizing technique. Our unsupervised adaptation approach using feature mapping, also complements its supervised counterpart, where adaptation is done using labeled data from both domains. We focus on three domain mismatch scenarios: (1) sampling frequency mismatch between the domains, (2) channel mismatch, and (3) robustness to far-field and noisy speech acquired from wild conditions.
- Najim Dehak, Department of Electrical and Computer Engineering
- Jesús Villalba, Department of Electrical and Computer Engineering
- Hynek Hermansky, Department of Electrical and Computer Engineering
- Sanjeev Khudanpur, Department of Electrical and Computer Engineering