Application of free sorting tasks to sound quality experiments

International audienceIn many studies devoted to the sound quality of industrial products, a perceptual space is determined through dissimilarity judgements on pairs of stimuli. A drawback of this procedure is that it can be very time consuming if the number of stimuli is large. An alternative procedure consists in a free sorting of sounds: averaging individual results provides a set of data which are considered as indicators of dissimilarities and analyzed using a multi-dimensional scaling method. The validity of this alternative can be discussed, as the psychological processes involved in the two procedures are different. This study compared these two approaches in a particular case (door closure sounds). In this specific case, it was observed that dissimilarities obtained from the two procedures can be different, the more so as sounds are dissimilar and these differences can lead to slightly different perceptual spaces. Nevertheless, a free sorting experiment is a reliable way of reducing the number of stimuli in a large set of sounds. It allows selecting some representative sounds and narrowing the set of sounds while keeping in the subset most of the timbre features. This provides a useful preliminary step to a paired-comparison experiment

Influence of Train Colour on Loudness Judgments

International audienceThis study replicates an experiment described by Patsouras et al. [5] or Rader et al. [8] in which subjects had to evaluate the loudness of a passing-by train noise while watching pictures of the train, the colour of which being varied. In contrast to these studies, no influence of train colour on loudness evaluation could be found. This discrepancy might be due to cultural differences (French subjects vs. German or Japanese ones). But a more realistic reason can be a jury sampling effect, as this influence can exist for very few subjects (one among twenty-two in this experiment)

Categorisation: a useful tool for applied perceptive studies

6 pagesInternational audienceCategorisation is a very common way we perceive our sound environment and, as so, was widely studied. Nevertheless, categorisation experiments are not so often used in applied studies. The goal of this paper is to show that it can be a very useful tool for reducing the number of stimuli without any loss of the generality of the context. That was checked in two cases : the first one dealt with door closing sounds. A large number of stimuli (35) was reduced to twelve thanks to a categorisation experiment; these twelve stimuli could then be used in a similarity rating experiment, enabling to know the perceptual space of such sounds. The second case involved sound computed from a simple model in which some structural variabilities were used. In that case, the perceptual spaces derived from the categorisation experiment and the similarity ratings one were very close to each other

Simulated transfer path accuracy vs. sound perception

International audienceThe use of numerical methods is becoming more and more common in industry design processes. However, to finely represent the physics of the problem, numerical models are always more complex and time consuming. In the meantime, sound perception is now a very important topic for car manufacturers, who try to predict sound quality during the development phase of the vehicle. It is therefore useful to get some ideas about how accurate a simulation should be in order to be used in sound quality applications. The goal of this paper is to understand the minimum accuracy of simulated transfer paths (TPs) required to give meaningful psychoacoustic results. A physical model is build and the associated Finite Element (FE) model is setup, validated and taken as reference. Then, some deteriorations of the FE model are introduced and a sensitivity analysis checks how those changes affect objective metrics associated to the TPs. Laslty, hearing tests are performed in order to understand how people percieve the differencies in the various simulated sounds

Noise source separation in diesel engines: application to acoustic listening tests

International audienceThis article discusses the extraction of combustion noise from diesel engines using a Wiener filter. Using the ESPRIT method, the filter is set to a limited number of modes, in order to reduce the amount of information it contains. It is estimated for various engine settings (load and engine speed). For this reason, real filters and their estimations are used to synthesise the noises. A perceptive experiment is conducted on these sounds in order to ensure that certain parameter filters enable the extraction of sounds similar to the combustion noises obtained by the measured filters. The aim of this work is therefore to evaluate the influence of the filter estimation conditions on the perception of the combustion noises that they help to synthesise

Spectrofiltre adapté à la séparation de sources cohérentes et entrelacées dans le plan temps-fréquences

Cette étude montre formellement et numériquement que le spectrofiltre peut séparer des sources cohérentes qui se chevauchent en temps et en fréquences. Pour en être capable, le spectrofiltre nécessite seulement d'être calculé à partir de la partie non déterministe des signaux connus. Son application au bruit du moteur Diesel est donc envisageable pour séparer le bruit de combustion des bruits mécaniques et notamment du bruit de basculement de piston

Percepción Sonora de Vehículos Eléctricos

Los vehículos eléctricos e híbridos (EVs y HEVs) están llamados a ser el futuro del transporte en ciudades inteligentes y la clave para la reducción total del ruido y la polución en áreas urbanas. Sin embargo, para garantizar la seguridad vial deben solucionarse diversos problemas asociados a este tipo de vehículos. Hasta el momento, el uso de HEVs ha puesto de manifiesto el incremento del riesgo en entornos urbanos debido a la presencia de un sistema de transporte completamente silencioso. Las distintas administraciones están analizando el problema, siendo la medida más significativa hasta ahora el uso de Sistemas Acústicos de Alerta de Vehículos (AVAS). El objetivo de este artículo es analizar el comportamiento acústico de los vehículos híbridos y eléctricos a partir de las principales contribuciones científicas.Electric and hybrid Electric vehicles (EVs and HEVs) seem to be the future of transport in smart cities and the key for the total reduction of noise disturbance and pollution in urban areas. However, several problems have to be solved in order to guarantee the safety of these types of vehicles. So far, the use of HEVs has shown the danger of a «quiet» transport system in urban environments. The Competent Authorities are addressing the problem and the most significant proposal up to now is the use of Acoustic Vehicles Alerting Systems (AVAS). The aim of this chapter is to collect the main contributions regarding the acoustic behaviour of hybrid electric vehicles and electric vehicles

Auditory perception of structural uncertainty

6 pagesInternational audienceBecause of structural uncertainty, an industrial object resulting from mass production can exhibit a large variability in its vibratory and acoustical behaviour. Some previous studies have focused on the variation in noise and vibration between structures with nominally identical design. Sounds emitted by these structures were also modified. Thus it might be thought that sound perception would vary as well because of structural variability. However, that problem has not yet been investigated. The aim of this study was to show how to assess the perceptual consequences of that physical variability. A mechanical model system, on which structural uncertainty could be simulated, was set up for sound synthesis. The sounds "emitted" by three different types of products were then assessed by a group of listeners performing a categorization task. The purpose was to determine if sounds stemming from nominally identical objects were always categorized together or if sounds emitted by nominally different objects could be confused. This experiment enabled to find the optimal partition of the stimulus set. Even though subclasses appeared within stimuli representing one type of object, sounds synthesized with different types of objects were not confused

Nuisance sonore dans les bureaux ouverts

National audienceLe niveau de bruit dans les bureaux ouverts n'est pas élevé - mais le bruit est toujours cité comme une source majeure de gêne par les occupants. Cela est sans doute dû à la nature particulière de ce bruit (composé essentiellement de voix). Cette présentation décrira les effets particuliers de ce type de bruit et les modes d'évaluation de ces effets, ainsi que les difficultés et limites des expériences en laboratoire. Elle présentera les indicateurs acoustiques actuellement proposés pour décrire cette nuisance