Assessment of spatial audio quality based on sound attributes

International audienceSpatial audio technologies become very important in audio broadcast services. But, there is a lack of methods for evaluating spatial audio quality. Standards do not take into account spatial dimension of sound and assessments are limited to the overall quality particularly in the context of audio coding. Through different elicitation methods, a long list of attributes has been established to characterize sound but it is difficult to include them in a listening test. A previous study aimed at clustering attributes in families. Thus 3 families of attributes were highlighted, ''timbre", ''space" and ''defaults". The overall quality and these three families were evaluated in the listening test presented in this article. The test protocol was based on the Mushra recommendation. However it included three anchors specific to each attribute and no reference in order to evaluate quality instead of fidelity. The aim of the experiment described in this paper was to verify the influence of those 3 attributes on the overall quality in a 5.1 reproduction system. It results that the defaults attribute has more influence on the overall quality than the timbre and the timbre. Moreover the presentation of the three attributes on the same interface adds no bias

TRY plant trait database – enhanced coverage and open access

Plant traits - the morphological, anatomical, physiological, biochemical and phenological characteristics of plants - determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits - almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

Elaboration d'une méthode de test pour l'évaluation subjective de la qualité des sons spatialisés

Nowadays, recording and restitution technologies focus on a spatial rendering of sound. Before their broadcast, the quality evaluation of sound excerpts is often necessary. Methods recommended by the international telecommunication union denote some weaknesses about sound attributes to be evaluated.For example, spatial dimension is barely taken into account. A methodology dedicated to the assessment of spatial audio quality is proposed in order to avoid some biases. With a free categorization and a multidimensional scaling, 28 attributes were clustered in three families '. Timbre, Space and Defecfs. These three categories were included in a listening test split into two sessions : first, the assessment of overall quality and then, the evaluation of the three categories presented simultaneously on a same interface.Tests were conducted without explicit reference, but, the original version was considered as a hidden reference. Moreover, three specific anchors, each one associated to dedicated categories, were defined and then were mixed to define a unique anchor impaired in three ways. The method was tested on a 5.1 system and on binaural contents with headphone restitution. lntermediate quality of contents is recommended as well as contents with relevant spatial effects. The interest of a multicriteria assessment is to identify which properties of sound are impaired. Linear regression shows that Defecfs and Timbre attributes have influential weight on overall quality while the weight of Space attribute is more dubious.Aujourd'hui, les technologies de captation et de restitution sonore se développent dans le but de diffuser des scènes avec un rendu spatialisé. Avant leur diffusion, les extraits sonores peuvent être évalués en terme de qualité par des méthodes recommandées par I'Union lnternationale des Télécommunications (évaluation des codecs de compression, procédés de prise ou restitution sonore...). Cependant, ces standards d'évaluation montrent certaines faiblesses notamment en ce qui concerne les attributs de qualité à évaluer. La dimension spatiale n'est pas prise en compte spécifiquement. Dans ce travail, une méthodologie dédiée à l'évaluation de la qualité de I'audio spatialisé est mise en place notamment pour répondre aux biais identifiés. De par l'utilisation d'une catégorisation libre et d'une analyse multidimensionnelle, vingt-huit attributs ont été catégorisés en trois familles d'attributs : le Timbre, l'Espace et les Défauts. Ces trois attributs généraux ont été inclus dans un test d'écoute. Celui-ci se déroule en deux phases : l'évaluation de la qualité globale suivie de l'évaluation des trois attributs simultanément sur une même interface. Les tests sont réalisés sans référence explicite, le fichier original constitue une référence cachée. De plus, trois signaux audio, dit ancrages, spécifiques à chacun des trois attributs ont été définis puis superposés pour définir un ancrage unique triplement dégradé. La méthode a été testée à la fois sur un système de restitution au casque avec des contenus binauraux mais également sur un système multicanal 5.1. L'évaluation de stimuli de qualité intermédiaire est préconisée ainsi que des contenus présentant un effet spatial prononcé. L'évaluation multicritère a montré son intérêt dans certaines conditions et permet ainsi d'identifier les caractéristiques qui sont dégradées. Les attributs Défauts et Timbre ont montré un poids influant sur la qualité globale tandis que le poids de I'attribut Espace est plus discutable

Method for the subjective evaluation os spatial sound quality

Aujourd'hui, les technologies de captation et de restitution sonore se développent dans le but de diffuser des scènes avec un rendu spatialisé. Avant leur diffusion, les extraits sonores peuvent être évalués en terme de qualité par des méthodes recommandées par I'Union lnternationale des Télécommunications (évaluation des codecs de compression, procédés de prise ou restitution sonore...). Cependant, ces standards d'évaluation montrent certaines faiblesses notamment en ce qui concerne les attributs de qualité à évaluer. La dimension spatiale n'est pas prise en compte spécifiquement. Dans ce travail, une méthodologie dédiée à l'évaluation de la qualité de I'audio spatialisé est mise en place notamment pour répondre aux biais identifiés. De par l'utilisation d'une catégorisation libre et d'une analyse multidimensionnelle, vingt-huit attributs ont été catégorisés en trois familles d'attributs : le Timbre, l'Espace et les Défauts. Ces trois attributs généraux ont été inclus dans un test d'écoute. Celui-ci se déroule en deux phases : l'évaluation de la qualité globale suivie de l'évaluation des trois attributs simultanément sur une même interface. Les tests sont réalisés sans référence explicite, le fichier original constitue une référence cachée. De plus, trois signaux audio, dit ancrages, spécifiques à chacun des trois attributs ont été définis puis superposés pour définir un ancrage unique triplement dégradé. La méthode a été testée à la fois sur un système de restitution au casque avec des contenus binauraux mais également sur un système multicanal 5.1. L'évaluation de stimuli de qualité intermédiaire est préconisée ainsi que des contenus présentant un effet spatial prononcé. L'évaluation multicritère a montré son intérêt dans certaines conditions et permet ainsi d'identifier les caractéristiques qui sont dégradées. Les attributs Défauts et Timbre ont montré un poids influant sur la qualité globale tandis que le poids de I'attribut Espace est plus discutable.Nowadays, recording and restitution technologies focus on a spatial rendering of sound. Before their broadcast, the quality evaluation of sound excerpts is often necessary. Methods recommended by the international telecommunication union denote some weaknesses about sound attributes to be evaluated.For example, spatial dimension is barely taken into account. A methodology dedicated to the assessment of spatial audio quality is proposed in order to avoid some biases. With a free categorization and a multidimensional scaling, 28 attributes were clustered in three families '. Timbre, Space and Defecfs. These three categories were included in a listening test split into two sessions : first, the assessment of overall quality and then, the evaluation of the three categories presented simultaneously on a same interface.Tests were conducted without explicit reference, but, the original version was considered as a hidden reference. Moreover, three specific anchors, each one associated to dedicated categories, were defined and then were mixed to define a unique anchor impaired in three ways. The method was tested on a 5.1 system and on binaural contents with headphone restitution. lntermediate quality of contents is recommended as well as contents with relevant spatial effects. The interest of a multicriteria assessment is to identify which properties of sound are impaired. Linear regression shows that Defecfs and Timbre attributes have influential weight on overall quality while the weight of Space attribute is more dubious

Sound Quality Evaluation Based on Attributes - Application to Binaural Contents

International audienceThe audio quality assessment is based on standards which mainly evaluate the overall quality to the detriment of more accurate sound criteria. On the other hand, a major problem of an assessment based on sound criteria is their meaning and their understanding that have to be the same for each listener. A previous study clustered a list of sound attributes in three main categories called 'timbre', 'space', 'defaults'. The work presented here is based on those previous results and aims at tuning a subjective test methodology of spatial audio quality. So the three families were included in a test dedicated to the assessment of spatial audio quality with binaural contents. The test was based on the MUSHRA method but using three anchors specifically to each attribute and without explicit reference. The original version was added as the hidden reference. The aim of the listening test described in this paper was to verify the relevance of those 3 attributes and their influence on the overall quality

State of the art on subjective assessment of spatial sound quality

International audienceA new aim of sound technologies is spatial reproduction, which raises new questions about their quality assessment. This literature review deals with spatial audio quality: for audio coding, assessment is made through use of two mainly subjective ITU-R test methods. But, they are restricted to the evaluation of the overall quality. The finding, through various studies, of some features specific to surround sound drove us to wonder whether they can be included in a new quality assessment

Categorization of Sound Attributes for Audio Quality Assessment — A Lexical Study

International audienceFor the evaluation of perceived quality in audio coding, two well-known subjective test methods, both of which are based on Basic Audio Quality (BAQ), are recommended by the International Telecommunication Union. Although a predictor of quality, BAQ is likely to be multidimensional. Listening tests can be used to evaluate other attributes that contribute to impairments created by coding. The goal of this study is to define categories of additional attributes, thereby providing a complement to the single BAQ metric. When quality attributes are sorted, there appears to be three groups: one related to space, a second related to defects, and a third split into timbre and quality

Families of sound attributes for assessment of spatial audio

8 pages http://www.aes.org/e-lib/browse.cfm?elib=15728International audienceOver the last years, studies have highlighted many features liable to be used for the characterization of sounds by several elicitation methods. These various experiments have resulted in the production of a long list of sound attributes. But, as their respective meaning and weight are not alike for assessors and listeners, the analysis of the results of a listening test based on sound criteria remains complex and difficult. The experiments reported in this paper were aimed at shortening the list of attributes by clustering them in sound families from the results of two semantic tests based on either a free categorization (i) or use of a multi-dimensional scaling method (ii)

Determination of a relevant spatial anchor for audio quality evaluation of codecs

International audienceIn most tests on audio quality, a "low quality" anchor is provided concurrently with the sequences to be evaluated. A classic generic anchor consists of a low-pass filtered version of the audio reference; but evaluation of specific sound properties (for example spatial features) could require a specific anchor. In a first experiment, we evaluated five spatial anchors to find which was the most appropriate for a test including evaluation of Space quality. One of the tested anchors obtained low scores for all the excerpts used. In a second experiment, a copy of this anchor was integrated into an evaluation test of audio codecs, with assessment of the categories Timbre, Defects, and Space. The scores obtained in this test indicated that this anchor fulfilled the required criteria (a low score for the anchor over all excerpts, the correct range of codec scores for Space, and no serious degradation for Timbre and Defects)

Evaluating functional diversity: missing trait data and the importance of species abundance structure and data transformation

Functional diversity (FD) is an important component of biodiversity that quantifies the difference in functional traits between organisms. However, FD studies are often limited by the availability of trait data and FD indices are sensitive to data gaps. The distribution of species abundance and trait data, and its transformation, may further affect the accuracy of indices when data is incomplete. Using an existing approach, we simulated the effects of missing trait data by gradually removing data from a plant, an ant and a bird community dataset (12, 59, and 8 plots containing 62, 297 and 238 species respectively). We ranked plots by FD values calculated from full datasets and then from our increasingly incomplete datasets and compared the ranking between the original and virtually reduced datasets to assess the accuracy of FD indices when used on datasets with increasingly missing data. Finally, we tested the accuracy of FD indices with and without data transformation, and the effect of missing trait data per plot or per the whole pool of species. FD indices became less accurate as the amount of missing data increased, with the loss of accuracy depending on the index. But, where transformation improved the normality of the trait data, FD values from incomplete datasets were more accurate than before transformation. The distribution of data and its transformation are therefore as important as data completeness and can even mitigate the effect of missing data. Since the effect of missing trait values pool-wise or plot-wise depends on the data distribution, the method should be decided case by case. Data distribution and data transformation should be given more careful consideration when designing, analysing and interpreting FD studies, especially where trait data are missing. To this end, we provide the R package “traitor” to facilitate assessments of missing trait data