Takao Murakami

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Claimants and enrollees who have high similarity scores against many others are referred to as wolves and lambs, respectively. These animals can cause false accepts against many others and compromise the security of the system. The aim of this paper is to develop a fusion algorithm which has security against both of them while minimizing the number of query(More)
Biometric identification has lately attracted attention because of its high convenience; it does not require a user to enter a user ID. The identification accuracy, however, degrades as the number of the enrollees increases. Although many multimodal biometric techniques have been proposed to improve the identification accuracy, it requires the user to input(More)
Speech acoustics is inevitably distorted by non-linguistic features such as vocal tract length, gender, age, microphone, room, line, hearing characteristics, and so on. Recently, a novel acoustic representation of speech was proposed, called the acoustic universal structure[1, 2]. It discards all the absolute properties of speech events and captures only(More)
Speech acoustics varies from speaker to speaker, microphone to microphone, room to room, line to line, etc. Physically speaking , every speech sample is distorted. Socially speaking, however , speech is the easiest communication media for humans. In order to cope with the inevitable distortions, speech engineers have built HMMs with speech data of hundreds(More)
Biometric identification provides a very convenient way to authenticate a user because it does not require the user to claim an identity. However, both the identification error rates and the response time increase almost in proportion to the number of enrollees. A technique which decreases both of them using only scores has the advantage that it can be(More)
We aim at reducing the number of distance computations as much as possible in the inexact indexing schemes which sort the objects according to some promise values. To achieve this aim, we propose a new probability-based indexing scheme which can be applied to any inexact indexing scheme that uses the promise values. Our scheme (1) uses the promise values(More)
Recent studies have proposed various attacks against location privacy using a Markov Chain transition matrix trained for each user. However, when a user has disclosed only a small amount of location information in the past, the training data can be extremely sparse. In this paper, we show how the attacker can solve this sparse data problem, and how the(More)
This paper proposes a novel paradigm of speech recognition where only the supra-segmental features are utilized. Absolute properties of speech events such as formants and spectrums are completely discarded and only the relative and differential properties of the events are extracted as phonic contrasts. The phonic contrasts are considered as supra-segmental(More)