Effect of stimulus type and pitch salience on pitch-sequence processing

Using a same-different discrimination task, it has been shown that discrimination performance for sequences of complex tones varying just detectably in pitch is less dependent on sequence length (1, 2, or 4 elements) when the tones contain resolved harmonics than when they do not [Cousineau, Demany, and Pessnitzer (2009). J. Acoust. Soc. Am. 126, 3179-3187]. This effect had been attributed to the activation of automatic frequency-shift detectors (FSDs) by the shifts in resolved harmonics. The present study provides evidence against this hypothesis by showing that the sequence-processing advantage found for complex tones with resolved harmonics is not found for pure tones or other sounds supposed to activate FSDs (narrow bands of noise and wide-band noises eliciting pitch sensations due to interaural phase shifts). The present results also indicate that for pitch sequences, processing performance is largely unrelated to pitch salience per se: for a fixed level of discriminability between sequence elements, sequences of elements with salient pitches are not necessarily better processed than sequences of elements with less salient pitches. An ideal-observer model for the same-different binary-sequence discrimination task is also developed in the present study. The model allows the computation of d' for this task using numerical methods

What is a melody?:on the relationship between pitch and brightness of timbre

Previous studies showed that the perceptual processing of sound sequences is more efficient when the sounds vary in pitch than when they vary in loudness. We show here that sequences of sounds varying in brightness of timbre are processed with the same efficiency as pitch sequences. The sounds used consisted of two simultaneous pure tones one octave apart, and the listeners' task was to make same/different judgments on pairs of sequences varying in length (one, two, or four sounds). In one condition, brightness of timbre was varied within the sequences by changing the relative level of the two pure tones. In other conditions, pitch was varied by changing fundamental frequency, or loudness was varied by changing the overall level. In all conditions, only two possible sounds could be used in a given sequence, and these two sounds were equally discriminable. When sequence length increased from one to four, discrimination performance decreased substantially for loudness sequences, but to a smaller extent for brightness sequences and pitch sequences. In the latter two conditions, sequence length had a similar effect on performance. These results suggest that the processes dedicated to pitch and brightness analysis, when probed with a sequence-discrimination task, share unexpected similarities

Evaluation psychoacoustique du traitement de séquences auditives

Le vieillissement de la population, et l'apparition de plus en plus précoce de formes de surdité suite à des traumatismes acoustiques font des questions relatives à la malentendance un vrai problème de société. Dans cette thèse, nous avons étudié des aspects fondamentaux et cliniques de la perception de séquences de sons. Les séquences de hauteur jouent un rôle important dans de nombreuses situations auditives: elles transmettent la prosodie;elles sont la base de mélodies; et elles sont un indice très important pour permettre l'écoute dans le bruit. Nous avons montré que la perception de séquences de hauteur repose sur des mécanismes spécifiques chez le normo-entendant, et que la restauration de l'accès à ces mécanismes est une étape nécessaire à l'amélioration de la qualité de la perception avec un implant cochléaire. Cette thèse apporte donc des éléments expérimentaux et cliniques originaux, ainsi qu'une nouvelle méthode pour l'étude de cet aspect important et jusqu'à présent peu considéré de la perception auditive qu'est le traitement de séquences.In this thesis, we have studied fundamental and clinical aspects of the perception of sequences of sounds. Pitch sequence play an important role in many situations: they convey the prosody of speech; they are used to construct melodies; and they are a very important cue for hearing in noisy environments. We have shown that the perception of pitch-sequences relies on specific mechanism in normal hearing listeners, and that restoring the access to these mechanisms in a necessary step on the way to improving the quality of perception with a cochlear implant. This thesis thus provides original experimental and clinical results, together with a new method to study this critical aspect of auditory processing, that of sequences.BOULOGNE-BU Psych. Henri Pieron (920125201) / SudocSudocFranceF

Frequency tagging to track the neural processing of contrast in fast, continuous sound sequences.

The human auditory system presents a remarkable ability to detect rapid changes in fast, continuous acoustic sequences, as best illustrated in speech and music. However, the neural processing of rapid auditory contrast remains largely unclear, probably due to the lack of methods to objectively dissociate the response components specifically related to the contrast from the other components in response to the sequence of fast continuous sounds. To overcome this issue, we tested a novel use of the frequency-tagging approach allowing contrast-specific neural responses to be tracked based on their expected frequencies. The EEG was recorded while participants listened to 40-s sequences of sounds presented at 8Hz. A tone or interaural time contrast was embedded every fifth sound (AAAAB), such that a response observed in the EEG at exactly 8 Hz/5 (1.6 Hz) or harmonics should be the signature of contrast processing by neural populations. Contrast-related responses were successfully identified, even in the case of very fine contrasts. Moreover, analysis of the time course of the responses revealed a stable amplitude over repetitions of the AAAAB patterns in the sequence, except for the response to perceptually salient contrasts that showed a buildup and decay across repetitions of the sounds. Overall, this new combination of frequency-tagging with an oddball design provides a valuable complement to the classic, transient, evoked potentials approach, especially in the context of rapid auditory information. Specifically, we provide objective evidence on the neural processing of contrast embedded in fast, continuous sound sequences. Recent theories suggest that the basis of neurodevelopmental auditory disorders such as dyslexia might be an impaired processing of fast auditory changes, highlighting how the encoding of rapid acoustic information is critical for auditory communication. Here, we present a novel electrophysiological approach to capture in humans neural markers of contrasts in fast continuous tone sequences. Contrast-specific responses were successfully identified, even for very fine contrasts, providing direct insight on the encoding of rapid auditory information

Chapitre 6. L’engagement des avocats de la défense

La représentation des accusés en matière pénale est un des rôles fondamentaux que jouent les avocats de la défense. Leur connaissance du système et des procédures comme leur compréhension des risques encourus par le justiciable sont cruciales pour l’avenir de ce dernier. Bien souvent, ils sont les seuls à pouvoir non seulement l’aider à saisir et à démêler les enjeux associés aux accusations dont il fait l’objet, mais également lui garantir une défense pleine et entière. Informé de la situati..

On the Relevance of Natural Stimuli for the Study of Brainstem Correlates: The Example of Consonance Perception

Some combinations of musical tones sound pleasing to Western listeners, and are termed consonant, while others sound discordant, and are termed dissonant. The perceptual phenomenon of consonance has been traced to the acoustic property of harmonicity. It has been repeatedly shown that neural correlates of consonance can be found as early as the auditory brainstem as reflected in the harmonicity of the scalp-recorded frequency-following response (FFR). “Neural Pitch Salience” (NPS) measured from FFRs—essentially a time-domain equivalent of the classic pattern recognition models of pitch—has been found to correlate with behavioral judgments of consonance for synthetic stimuli

Pleasantness ratings plotted against Neural Pitch Salience (NPS) for synthetic complex tones (sCT, left panel), saxophone recordings (Sax, middle panel) and voice recordings (Voice, right panel).

<p>The three intervals are color-coded: Unison: blue; m2: green; P5: red. Correlation coefficient and p value for the correlation are reported in each panel.</p

Mean pleasantness ratings for intervals ranging from the unison to the perfect fifth (P5) for synthetic complex tones (sCT, squares), saxophone recordings (Sax, diamonds) and voice recordings (Voice, circles).

<p>The three intervals for which FFR were recorded (unison, m2 and P5) are marked in blue, green and red respectively. Error bars represent +/- standard error about the mean.</p