Ultrasonic Evaluation of Case Depth in Case-Carburized Steel Components

Performance of many engineering components depends to a large extent on their near surface characteristics, which in turn are affected by wear, corrosion, and fatigue in the presence of loading forces. One way to improve the engineering component’s performance is to tailor the surface properties using laser and electron beam processing, coatings, ion-implantation, and carburizing

Perception of unattended speech

Presented at the 10th International Conference on Auditory Display (ICAD2004)This study addresses the question of speech processing under unattended conditions. Dupoux et al. (2003) have recently claimed that unattended words are not lexically processed. We test their conclusion with a different paradigm : participants had to detect a target word belonging to a specific category presented in a rapid list of words, in the attended ear. In the unattended ear, concatenated sentences were presented, some containing a repetition prime presented just before the target words. We found a significant priming effect of 22 ms (Experiment 1), for category detection in the presence of a prime compared with no prime. This priming effect was not affected by whether the right or the left ear received the prime (Experiment 2a and 2b). We also found that the priming effect disappeared when there was no pitch range difference between attended and unattended messages (Experiment 3 and 4). Finally, we replicated the priming effect by compelling participants to focus on the attended message asking them to perform a second task (Experiment 5)

Listening to environmental scenes in real time

Presented at the 8th International Conference on Auditory Display (ICAD), Kyoto, Japan, July 2-5, 2002.Our perception of auditory environmental scenes depends on both the context in which the sources occur and the way in which we listen to them (if we are focused on some sources or not). This study investigates processing differences for a single source depending on its context of occurrence. A tone-detection paradigm adapted to an everyday listening context compares the ability to detect tones in a focused stream within three 10- second non-focused streams: an environmental scene, a white noise and a silence. We predict fluctuations in detection times as a function of the number of streams in the context and of the changes occurring in the non-focused stream

Perception of urgency and alarm design

Presented at the 8th International Conference on Auditory Display (ICAD), Kyoto, Japan, July 2-5, 2002.Psychophysical approaches to urgency perception have identified acoustical properties modulating the perceived degree of urgency. However acoustical properties seemed less efficient in inducing perception of urgency when subjects were under high workload. The aim of the first experiment was to confirm, with a multidimensional approach, the validity of the acoustic parameters in urgency perception described by Edworthy et al. [1]. The aim of the second experiment was to generalize the results obtained to real alarms. The multidimensional scaling approach confirmed the important role of acoustic properties of the alarms in the case of the artificial alarms of Experiment 1, but not with the real alarms of Experiment 2. The generation of alarms using only psychophysical tools cannot be generalized. The mental representation of the sequence probably interacts with the acoustical properties. This should have implications for alarm design

Identification of environmental sounds: Role of rhythmic properties

Presented at the 12th International Conference on Auditory Display (ICAD), London, UK, June 20-23, 2006.Studies that have dealt with the effect of sound spectral and temporal properties on environmental sound identification have focused on a narrow range of sounds [1, 2, 3]. The purpose of the research was to evaluate the effect of sound temporal characteristics on the identification of 72 different environmental sounds, 29 of them having a rhythmic structure. We used a gating paradigm, involving a successive presentation of increasing increment of gates stimulus [4] that listeners had to identify. The minimum amount of time presentation (uniqueness point) for which an environmental sound was correctly recognized was recorded. We found that rhythmic sounds were identified earlier (tR = 160 ms) than non rhythmic (tNR = 239 ms). Furthermore, for rhythmic sounds, we observed a significant correlation between the uniqueness point and the duration of the first inter onset interval (r = 0.65). Our results suggest that sound rhythmic structure is an informative parameter in the identification process

Comment améliorer la sélection et le traitement de messages verbaux?

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IMAGES ACOUSTIQUES VISUALISÉES PAR UNE CAMÉRA ULTRASONORE. AVANTAGES ET INCONVÉNIENTS PAR RAPPORT AUX AUTRES MÉTHODES DE VISUALISATION

Les diverses méthodes permettant de produire des images ultrasonores sont passées en revue. Chaque principe de base utilisé est souligné et on insiste tout particulièrement sur le seuil de sensibilité de chaque méthode, ainsi que sur le temps nécessaire à la production d'une image. Ce rapide passage en revue comprend quelques discussions sur quatre catégories de méthodes de détection, les procédés thermiques, les procédés photographiques et chimiques, optiques et mécaniques, et les procédés électroniques. Pour ces catégories le seuil de sensibilité varie d'environ 1 W/cm2 pour les procédés photographiques et pour les procédés chimiques, à des valeurs de l'ordre de 10-11 W/cm2 pour les procédés électroniques. Parmi ces derniers, la visualisation par caméra à ultrasons présente l'avantage de délivrer une image de manière pratiquement instantanée. Malheureusement, la dimension de l'image est limitée par le fait que la face sensible de la caméra doit supporter la pression atmosphérique. L'obligation d'utiliser très souvent une onde ultrasonore continue apporte également par l'influence d'interférences et d'ondes stationnaires de sérieuses difficultés. Des essais effectués sur des caméras fonctionnant avec des impulsions ultrasonores ont apporté des améliorations sensibles. Les perfectionnements de ce type de tube de prise d'images ultrasonores devraient aboutir à un tube travaillant suivant deux séquences : la première prenant l'image acoustique en mémoire au moment où arrive l'impulsion d'ultrasons, la seconde effectuant la lecture par le faisceau d'électrons. Une autre solution consisterait à réaliser une superposition de couches piézoélectriques semi-conductrices et électroluminescentes transformant directement un relief de pression en image lumineuse.The various methods which enable to produce ultrasonic images are listed. Each basic princip is outlined with emphasis on the intensity level which is possible to detect and on the time required to produce an image. This brief survey includes some discussions about four types of methods using thermal, photographical, chemical and electronic devices. The intensity level varies from 1 W/cm2 for the three former to 10-11 W/cm2 for the latter. Within the latter, we are chiefly concerned with the camera, which offers the advantage of giving quasi-instantaneous images. Unfortunately, the size of the image is limited by considerations about pressure acting upon the piezoelectric plate. The use of continuous waves, as it is generally the case, introduces some other limitations coming from diffraction effects. Camera issuing from future improvements would work in two stages : First, acoustic images should be stored when the ultrasonic pulse impinges on the piezoelectric target, and in the second stage the charge pattern should be read by an electron beam. Another solution consist in superposing piezoelectric, semi-conductor, and electrominescent layers, converting directly a relief of pressure into a visible image

Perception of Urgency and Spatialization of Auditory Alarms

Alarms can be spatialized in new human-machine interfaces. This includes the perception of distance at different points in space. The aim of this work was to study the interferences between the perception of distance and the perception of urgency. Two experiments used common stimuli. These were sounds recorded on a dummy head from a white noise emitted from 8 directions in the azimuth plane and at 3 distances, inside a closed, empty room. The sounds were then loudness equalized. Experiment 1 consisted of presenting the sounds in pairs to the listeners, who had to designate the sound which was perceived as the most urgent. The results show that, for the same distance, the level of urgency is greater when the virtual source is at $\pm$90\,^{\circ}. They also show two types of responses concerning the links between the perception of distance and urgency. Certain listeners perceive near sounds as the most urgent, while others perceive distant sounds as the most urgent. Experiment 2 is a control experiment to check that perception of distance is preserved for these loudness equalized sounds