Private AI

Making privacy accessible to developers

Meet the team
The Team

Gerald Penn, PhD

Co-Founder and CSO

Gerald Penn is a Professor of Computer Science at the University of Toronto, where he studies spoken language processing and computational linguistics. He has over 100 publications, with the top one accruing 1,581 citations. He is a senior member of IEEE and AAAI, and a past recipient of the Ontario Early Researcher Award. His lab revolutionized speech recognition with its work on neural networks, which received the IEEE Signal Processing Society's Best Paper Award. He has led numerous research projects, including ones funded by Avaya, Bell Canada, CAE, the Connaught Fund, Microsoft, NSERC, the German Ministry for Training and Research, SMART Technologies, the U.S. Army and the U.S. Office of the Director of National Intelligence. Gerald has also worked at by Bell Labs and NASA.

Patricia Thaine, MSc

Co-Founder and CEO

Patricia Thaine is a Computer Science PhD Candidate at the University of Toronto doing research on privacy-preserving natural language processing, with a focus on applied cryptography. She also does research on computational methods for lost language decipherment. Patricia is a recipient of the NSERC Postgraduate Scholarship, the RBC Graduate Fellowship, the Beatrice “Trixie” Worsley Graduate Scholarship in Computer Science, and the Ontario Graduate Scholarship. She has eight years of research and software development experience, including at the McGill Language Development Lab, the University of Toronto's Computational Linguistics Lab, the University of Toronto's Department of Linguistics, and the Public Health Agency of Canada.

Pieter Luitjens, MEng

Co-Founder and CTO

Pieter Luitjen has a Bachelor of Science in Physics and Mathematics and a Bachelor of Engineering from the University of Western Australia, as well as a Masters from the University of Toronto. He worked on software for Mercedes-Benz and developed the first deep learning algorithms for traffic sign recognition deployed in cars made by one of the most prestigious car manufacturers in the world. He has over 10 years of engineering experience, with code deployed in multi-billion dollar industrial projects. Pieter specializes in ML edge deployment & model optimization for resource-constrained environments.


Advisors
Research
Extracting Mel-Frequency and Bark-Frequency Cepstral Coefficients from Encrypted Signals

We describe a method for extracting Mel-Frequency and Bark-Frequency Cepstral Coefficient from an encrypted signal without having to decrypt any intermediate values. To do so, we introduce a novel approach for approximating the value of logarithms given encrypted input data. This method works over any interval for which logarithms are defined and bounded. Extracting spectral features from encrypted signals is the first step towards achieving secure end-to-end automatic speech recognition over encrypted data. We experimentally determine the appropriate precision thresholds to support accurate WER for ASR over the TIMIT dataset.

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A Critical Reassessment of Evaluation Baselines for Speech Summarization

We assess the current state of the art in speech summarization, by comparing a typical summarizer on two different domains: lecture data and the SWITCHBOARD corpus. Our results cast significant doubt on the merits of this area’s accepted evaluation standards in terms of: baselines chosen, the correspondence of results to our intuition of what “summaries” should be, and the value of adding speech-related features to summarizers that already use transcripts from automatic speech recognition (ASR) system.

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Convolutional Neural Networks for Speech Recognition

Recently, the hybrid deep neural network (DNN)-hidden Markov model (HMM) has been shown to significantly improve speech recognition performance over the conventional Gaussian mixture model (GMM)-HMM. The performance improvement is partially attributed to the ability of the DNN to model complex correlations in speech features. In this paper, we show that further error rate reduction can be obtained by using convolutional neural networks (CNNs). We first present a concise description of the basic CNN and explain how it can be used for speech recognition. We further propose a limited-weight-sharing scheme that can better model speech features. The special structure such as local connectivity, weight sharing, and pooling in CNNs exhibits some degree of invariance to small shifts of speech features along the frequency axis, which is important to deal with speaker and environment variations. Experimental results show that CNNs reduce the error rate by 6%-10% compared with DNNs on the TIMIT phone recognition and the voice search large vocabulary speech recognition tasks.

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Privacy-Preserving Character Language Modelling

Some of the most sensitive information we generate is either written or spoken using natural language. Privacy-preserving methods for natural language processing are therefore crucial, especially considering the ever-growing number of data breaches. However, there has been little work in this area up until now. In fact, no privacy-preserving methods have been proposed for many of the most basic NLP tasks. We propose a method for calculating character bigram and trigram probabilities over sensitive data using homomorphic encryption.

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Please email us at info@private-ai.ca.