In this paper, we evaluate the performance of several objective measures in terms of predicting the quality of noisy speech enhanced by noise suppression algorithms. The objective measures considered a wide range of distortions introduced by four types of real-world noise at two signal-to-noise ratio levels by four classes of speech enhancement algorithms: spectral subtractive, subspace, statistical-model based, and Wiener algorithms. The subjective quality ratings were obtained using the ITU-T P.835 methodology designed to evaluate the quality of enhanced speech along three dimensions: signal distortion, noise distortion, and overall quality. This paper reports on the evaluation of correlations of several objective measures with these three subjective rating scales. Several new composite objective measures are also proposed by combining the individual objective measures using nonparametric and parametric regression analysis techniques.

Evaluation of Objective Quality Measures for Speech Enhancement

A modulation spectral representation is investigated for non-intrusive quality and intelligibility measurement of reverberant and dereverberated speech. The representation is obtained by means of an auditory-inspired filterbank analysis of critical-band temporal envelopes of the speech signal. Modulation spectral insights are used to develop an adaptive measure termed speech to reverberation modulation energy ratio. Experimental results show the proposed measure outperforming three standard algorithms for tasks involving estimation of multiple dimensions of perceived coloration, as well as quality measurement and intelligibility estimation of reverberant and dereverberated speech.

A Non-Intrusive Quality and Intelligibility Measure of Reverberant and Dereverberated Speech

Despite the growing and widespread use of glyphosate, a broad-spectrum herbicide and desiccant, very few studies have evaluated the extent and amount of human exposure. We review documented levels of human exposure among workers in occupational settings and the general population. We conducted a review of scientific publications on glyphosate levels in humans; 19 studies were identified, of which five investigated occupational exposure to glyphosate, 11 documented the exposure in general populations, and three reported on both. Eight studies reported urinary levels in 423 occupationally and para-occupationally exposed subjects; 14 studies reported glyphosate levels in various biofluids on 3298 subjects from the general population. Average urinary levels in occupationally exposed subjects varied from 0.26 to 73.5 μg/L; environmental exposure urinary levels ranged from 0.16 to 7.6 μg/L. Only two studies measured temporal trends in exposure, both of which show increasing proportions of individuals with detectable levels of glyphosate in their urine over time. The current review highlights the paucity of data on glyphosate levels among individuals exposed occupationally, para-occupationally, or environmentally to the herbicide. As such, it is challenging to fully understand the extent of exposure overall and in vulnerable populations such as children. We recommend further work to evaluate exposure across populations and geographic regions, apportion the exposure sources (e.g., occupational, household use, food residues), and understand temporal trends.

/pdf/the-evidence-of-human-exposure-to-glyphosate-a-review-3kfnb1x57g.pdf

The evidence of human exposure to glyphosate: a review

This article presents a tutorial overview of models for estimating the quality experienced by users of speech transmission and communication services. Such models can be classified as either parametric or signal based. Signal-based models use input speech signals measured at the electrical or acoustic interfaces of the transmission channel. Parametric models, on the other hand, depend on signal and system parameters estimated during network planning or at run time. This tutorial describes the underlying principles as well as advantages and limitations of existing models. It also presents new developments, thus serving as a guide to an appropriate usage of the multitude of current and emerging speech quality models.

Speech Quality Estimation: Models and Trends

Monitoring of speech quality in emerging heterogeneous networks is of great interest to network operators. The most efficient way to satisfy such a need is through nonintrusive, objective speech quality assessment. In this paper, we describe a low-complexity algorithm for monitoring the speech quality over a network. The features used in the proposed algorithm can be computed from commonly used speech-coding parameters. Reconstruction and perceptual transformation of the signal is not performed. The critical advantage of the approach lies in generating quality assessment ratings without explicit distortion modeling. The results from the performed experiments indicate that the proposed nonintrusive objective quality measure performs better than the ITU-T P.563 standard

Low-Complexity, Nonintrusive Speech Quality Assessment

Objective voice quality assessment has been the subject of research for many years. Up until very recently, objective models required a copy of the unprocessed signal for estimating the quality of a signal transmitted across a telecommunication network, making live call monitoring impossible. This paper introduces a method for nonintrusive assessment of speech quality for narrow-band telephony, which was approved by the International Telecommunication Union (ITU-T) in May 2004. Essentially based on models of voice production and perception, the algorithm demonstrates good performance on more than 48 subjective experiments representing most distortions that occur on voice networks

P.563&#8212;The ITU-T Standard for Single-Ended Speech Quality Assessment

A non-intrusive speech quality assessment system. A method and apparatus for training a quality assessment tool in which a database comprising a plurality of samples, each with an associated mean opinion score, is divided into a plurality of distortion sets of samples according to a distortion criterion; and a distortion specific assessment handler for each distortion set is trained, such that a fit between a distortion specific quality measure generated from a distortion specific plurality of parameters for a sample and the mean opinion score associated with said sample is optimised. A method and apparatus for assessing speech quality in a telecommunications network in which a dominant distortion type is determined for a sample; a distortion specific plurality of parameters are combined to provide a distortion specific quality measure for each sample; and a quality measure is generated in dependence upon the distortion specific quality measure.

Quality assessment tool

This paper reports on experiments to estimate the speech output quality of telephone services in an instrumental way, using single-ended quality prediction models. It addresses both naturally-produced as well as synthesized speech generated with a Text-To-Speech (TTS) system. Three auditory tests have been carried out where typical speech samples have been transmitted over various telephone channels, and then judged by listeners with respect to their overall quality. The mean auditory ratings obtained in these tests have been compared to estimates provided by three different single-ended models, one of which is currently recommended by the International Telecommunication Union for predicting the quality of naturally-produced speech. Correlations between auditory and estimated quality scores vary considerably between experiments. It is concluded that the single-ended models mainly predict the effects of the transmission channel, but not of the (naturally-produced or synthesized) source speech material.

Estimating the Quality of Synthesized and Natural Speech Transmitted Through Telephone Networks Using Single-ended Prediction Models

Telemeetings such as audiovisual conferences or virtual meetings play an increasingly important role in our professional and private lives. For that reason, system developers and service providers will strive for an optimal experience for the user, while at the same time optimizing technical and financial resources. This leads to the discipline of Quality of Experience (QoE), an active field originating from the telecommunication and multimedia engineering domains, that strives for understanding, measuring, and designing the quality experience with multimedia technology. This paper provides the reader with an entry point to the large and still growing field of QoE of telemeetings, by taking a holistic perspective, considering both technical and non-technical aspects, and by focusing on current and near-future services. Addressing both researchers and practitioners, the paper first provides a comprehensive survey of factors and processes that contribute to the QoE of telemeetings, followed by an overview of relevant state-of-the-art methods for QoE assessment. To embed this knowledge into recent technology developments, the paper continues with an overview of current trends, focusing on the field of eXtended Reality (XR) applications for communication purposes. Given the complexity of telemeeting QoE and the current trends, new challenges for a QoE assessment of telemeetings are identified. To overcome these challenges, the paper presents a novel Profile Template for characterizing telemeetings from the holistic perspective endorsed in this paper.

https://ieeexplore.ieee.org/ielx7/6287639/6514899/09777989.pdf

Quality of Experience in Telemeetings and Videoconferencing: A Comprehensive Survey

The conventional video subjective test design, in which subjects view and rate multiple versions of each source video sequence, was used for decades. New technology, like adaptive streaming, makes it almost impossible to use this design since much longer sequences are needed. In this paper we examine three experiment designs: the conventional design and two alternatives that use each source sequence only once. Based on data collected by three laboratories, we compare the accuracy and scoring behavior of these three designs. We check whether there is a significant difference in scoring behavior between the experiment designs. One of the proposed experiment designs is proposed for immediate use.

/pdf/evaluating-experiment-design-with-unrepeated-scenes-for-22kof1sqii.pdf

Ludovic Malfait

Papers

P.563—The ITU-T Standard for Single-Ended Speech Quality Assessment

Quality assessment tool

Estimating the Quality of Synthesized and Natural Speech Transmitted Through Telephone Networks Using Single-ended Prediction Models

Quality of Experience in Telemeetings and Videoconferencing: A Comprehensive Survey

Evaluating experiment design with unrepeated scenes for video quality subjective assessment

Ludovic Malfait

Papers

P.563&#8212;The ITU-T Standard for Single-Ended Speech Quality Assessment

Quality assessment tool

Estimating the Quality of Synthesized and Natural Speech Transmitted Through Telephone Networks Using Single-ended Prediction Models

Quality of Experience in Telemeetings and Videoconferencing: A Comprehensive Survey

Evaluating experiment design with unrepeated scenes for video quality subjective assessment

P.563—The ITU-T Standard for Single-Ended Speech Quality Assessment