1,721,088 research outputs found
Quasi-Lagrangian neural network for convex quadratic optimization
Full text linkA new neural network for convex quadratic optimization is presented in this brief. The proposed network can handle both equality and inequality constraints, as well as bound constraints on the optimization variables. It is based on the Lagrangian approach, but exploits a partial dual method in order to keep the number of variables at minimum. The dynamic evolution is globally convergent and the steady-state solutions satisfy the necessary and sufficient conditions of optimality. The circuit implementation is simpler with respect to existing solutions for the same class of problems. The validity of the proposed approach is verified through some simulation examples
Sul miglioramento dell’intelligibilità soggettiva e oggettiva ottenuto con tecniche di speech enhancement
No full textQuantifying the value of subjective and objective speech intelligibility assessment in forensic applications
Full text linkTranscription from lawful interception is an important branch of forensic phonetics. Signals in that
application context are often degraded, thus the transcript may not reflect what was really pronounced. In order to decide whether a given transcript generated from a lawful interception exercise reflects the views of the speakers instead of the transcriber’s, an objective speech intelligibility measurement method is required.
Usually, the intercepted signal can be affected by both speech intrinsic distortion and
background/environmental noise distortion. Unfortunately, the original clean speech is never accessible to the
forensic expert, who therefore must draw his assessment from the only available, distorted, signal.
Consequently, the only way to assess the level of accuracy that can be obtained in the transcription of poor recordings is to develop an objective methodology for intelligibility measurements.
This paper addresses the issue by using three different objective approaches - namely the Signal-to-Noise ratio weighted with the “A” curves (S/NA), the Articulation Index (AI) and the Speech Transmission Index (STI) - to evaluate the intelligibility of a given signal. All of the three approaches were exercised with different types of noise, yielding results to be compared with speech intelligibility scores from subjective tests. The outcome gives high correlation evidence between objective measurements and subjective evaluations. Therefore, the proposed methodology is deemed rather useful to establish whether a given intercepted signal can be transcribed with sufficient reliability
Intelligibility assessment in forensic applications
Full text linkIn the context of forensic phonetics the transcription of intercepted signals is particularly important. However, these signals are often degraded and the transcript may not reflect what was actually pronounced.
In the absence of the original signal, the only way to see the level of accuracy that can be obtained in the transcription of poor recordings is to develop an objective methodology for intelligibility measurements.
This study has been carried out on a corpus specially built to simulate the real conditions of forensic signals. With reference to this
corpus a measurement system of intelligibility based on STI (Speech Transmission Index) has been evaluated so as to assess its
performance. The result of the experiment shows a high correlation between objective measurements and subjective evaluations.
Therefore it is recommended to use the proposed methodology in order to establish whether a given intercepted signal can be transcribed with sufficient reliability
Cumulative and Ratio Time Evaluations in Keystroke Dynamics To Improve the Password Security Mechanism
Full text linkThe password mechanism is widely adopted as a control security system to legitimate access to a database or a transaction content or computing resources. This is because of the low cost of the mechanism, the software routine simplicity, and the facility for the user. But the password mechanism can suffer from serious vulnerabilities, which have to be reduced in some way. An aid comes from the keystroke dynamic evaluation, which uses the rhythm in which an individual types characters on a keyboard. It has been demonstrated how the keystroke dynamics are unique biometric template of the users typing pattern. So, the dwell time (the time a key pressed) and the flight time (the time between “key up” and the next “key down”) are used to verify the real user’s identity. In this work we investigated the keystroke dynamic already reported in literature but with some differences, so to obtain additional benefits. Rather than the commonly adopted absolute times (dwell and fly times), we deal with cumulative and ratio ones (i.e. sum and ratio of dwell and fly times), taking into account that the latest are times which do not change even if the user’s typing style evolves with practic
Event based transcription system for polyphonic piano music
Full text linkMusic transcription consists in transforming the musical content of audio data into a symbolic representation. The objective of this study is to investigate a transcription system for polyphonic piano, triggered by events corresponding to the played notes. The proposed method focuses on note events and their main characteristics: the attack instant, the pitch and the final instant. Onset detection exploits a binary time-frequency representation of the audio signal. Note classification and offset detection are based on constant Q transform (CQT) and support vector machines (SVMs). We present a collection of experiments using synthesized MIDI files and piano recordings. and compare the results with existing approaches. (C) 2009 Elsevier B.V. All rights reserved
Objective speech intelligibility measures based on speech transmission index for forensic applications
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