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Publications

Publications by Aníbal Ferreira

2017

A Conversational Medication Assistant for Heart Failure

Authors
Lobo, J; Ferreira, L; Ferreira, AJS;

Publication
INTERNATIONAL JOURNAL OF E-HEALTH AND MEDICAL COMMUNICATIONS

Abstract
The incidence of chronic diseases is increasing and monitoring patients in a home environment is recommended. Noncompliance with prescribed medication regimens is a concern, especially among older people. Heart failure is a chronic disease that requires patients to follow strict medication plans permanently. With the objective of helping these patients managing information about their medicines and increasing adherence, the personal medication advisor CARMIE was developed as a conversational agent capable of interacting, in Portuguese, with users through spoken natural language. The system architecture is based on a language parser, a dialog manager, and a language generator, integrated with already existing tools for speech recognition and synthesis. All modules work together and interact with the user through an Android application, supporting users to manage information about their prescribed medicines. The authors also present a preliminary usability study and further considerations on CARMIE.

2018

Acoustic analysis of voice signal: Comparison of four applications software

Authors
Vaz Freitas, S; Pestana, PM; Almeida, V; Ferreira, A;

Publication
BIOMEDICAL SIGNAL PROCESSING AND CONTROL

Abstract
Objectives: To describe the results of the acoustic analysis of a database of 90 voice samples with distinct dysphonia levels, using four different - commercial and open source - software programs. Study design: Exploratory, transversal. Methods: The samples were analyzed by four different types of software programs that perform acoustical evaluation - one open source software (Praat) and three commercial ones (Multi Dimensional Voice Program - MDVP by Kay Elemetrics; VoiceStudio by Seegnal; and Dr. Speech by Tiger Electronics) - for comparison among the most commonly used acoustic measures (frequency, perturbation and noise measures). Results: There is a moderate to strong,correlation, positive and statistically significant among the software programs. The mean FO is not statistically different among the used applications. The other acoustic measures revealed statistically significant differences. Conclusion: Even though it is easier to access software programs and there are numerous proposals for acoustic measures, not all of them are statistically representative nor have numeric semblance among the different applications.

2017

Consistency of the F0, Jitter, Shimmer and HNR voice parameters in GSM and VOIP communication

Authors
Ferreira, A; Fernandes, V;

Publication
International Conference on Digital Signal Processing, DSP

Abstract
Acoustic parameters are very useful in voice screening, diagnosis and rehabilitation, and also in forensic voice comparison tasks. In this paper we present results for the acoustic analysis performed by two different voice analysis platforms and involving five sustained vowels uttered by 10 female speakers and 9 male speakers. We consider contemporaneous high-quality (HQ) and GSM voice recordings, as well as HQ and VOIP voice recordings. The analysis of the consistency of the acoustic analysis results by the two platforms provides useful insight regarding the intrinsic robustness of each acoustic parameter, the impact of the communication channel, and appropriate procedures seeking to extract full benefit of the available data in a forensic voice context. © 2017 IEEE.

2016

IMPLANTATION OF VOICING ON WHISPERED SPEECH USING FREQUENCY-DOMAIN PARAMETRIC MODELLING OF SOURCE AND FILTER INFORMATION

Authors
Ferreira, A;

Publication
2016 INTERNATIONAL SYMPOSIUM ON SIGNAL, IMAGE, VIDEO AND COMMUNICATIONS (ISIVC)

Abstract
In this paper we address the transformation of whispered speech into natural voiced speech. Representative state-of-the-art solutions are first reviewed as well as a baseline algorithm. For the most part, these solutions fall in the realm of voice conversion strategies since the output signal is obtained as a projection of an input signal. In this paper, we propose a different approach that addresses flexible parametric synthesis of the voiced signal component, as well as its implantation on the whispered signal, in a linguistically consistent way and while trying to convey idiosyncratic information. The most critical functions of phonetic segmentation, spectral envelope estimation, arbitrary periodic wave shape synthesis, and F0 modulation, are described and their operation illustrated with examples.

2018

On the physiological validity of the group delay response of all-pole vocal tract modeling

Authors
Ferreira, AJ;

Publication
145th Audio Engineering Society International Convention, AES 2018

Abstract
Magnitude-oriented approaches dominate the voice analysis front-ends of most current technologies addressing e.g. speaker identification, speech coding/compression, voice reconstruction and re-synthesis. A popular technique is all-pole vocal tract modeling. The phase response of all-pole models is known to be non-linear and highly dependent on the magnitude frequency response. In this paper, we use a shift-invariant phase-related feature that is estimated from signal harmonics in order to study the impact of all-pole models on the phase structure of voiced sounds. We relate that impact to the phase structure that is found in natural voiced sounds to conclude on the physiological validity of the group delay of all-pole vocal tract modeling. Our findings emphasize that harmonic phase models are idiosyncratic, and this is important in speaker identification, and in fostering the quality and naturalness of synthetic and reconstructed speech. © 2018 KASHYAP.

2017

On the relevance of F0, Jitter, Shimmer and HNR acoustic parameters in forensic voice comparisons using GSM, VOIP and contemporaneous high-quality voice recordings

Authors
Fernandes, V; Ferreira, A;

Publication
Proceedings of the AES International Conference

Abstract
GSM and VOIP telephonic voice recordings are frequently used in forensic voice comparisons. However, speech compression, enhancement and error correction algorithms are likely to modify speaker specific voice characteristics. We performed high-quality voice recordings and concomitant GSM and VOIP telephonic voice recordings so that clean high-quality and telephonic versions of the same speech are available. Sustained vowel tasks are also included allowing F0 (AVG and STD), Jitter, Shimmer and HNR extraction for pairs of contemporaneous recordings. Twenty female and seventeen male volunteer subjects participated in the study. We describe the voice recording experiments, present results for five vowels and five acoustic parameters for each subject in GSM and VOIP communication, and we discuss the implications of the main results.

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