Les traces d'un son

En l'an 2200, on trouvera peut-être sur le bureau de tout bon compositeur de musique contemporaine un épais Atlas de la Mémoire Auditive Humaine. Imaginons par exemple qu'un de ces futurs compositeurs affectionne les bruits blancs et désire que le premier mouvement de sa nouvelle œuvre contienne un "thème" constitué par un segment arbitraire, mais fixe, de bruit blanc. Il faut qu'à l'écoute de l'œuvre, une répétition du thème soit reconnue comme telle. Quelle est donc la période maximale que peut avoir un bruit "blanc" – mais en fait périodique – que l'on entend comme périodique ? Le compositeur consultera l'Atlas pour le savoir, et verra au chapitre X que la réponse est (d'après Guttman et Julesz, 1964) : environ 1.5 seconde. (...

Modulation masking produced by second-order modulators

Recent studies suggest that an auditory nonlinearity converts second-order sinusoidal amplitude modulation (SAM) (i.e., modulation of SAM depth) into a first-order SAM component, which contributes to the perception of second-order SAM. However, conversion may also occur in other ways such as cochlear filtering. The present experiments explored the source of the first-order SAM component by investigating the ability to detect a 5-Hz, first-order SAM probe in the presence of a second-order SAM masker beating at the probe frequency. Detection performance was measured as a function of masker-carrier modulation frequency, phase relationship between the probe and masker modulator, and probe modulation depth. In experiment 1, the carrier was a 5-kHz sinusoid presented either alone or within a notched-noise masker in order to restrict off-frequency listening. In experiment 2, the carrier was a white noise. The data obtained in both carrier conditions are consistent with the existence of a modulation distortion component. However, the phase yielding poorest detection performance varied across experimental conditions between 0° and 180°, confirming that, in addition to nonlinear mechanisms, cochlear filtering and off-frequency listening play a role in second-order SAM perception. The estimated magnitude of the modulation distortion component ranges from 5%-12%

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

Effet d'une différence d'intensité sur la précision des ajustements dans une tâche d'égalisation des hauteurs tonales de deux sons purs

Summary : The effect of intensity differences on the accuracy of matching pure tones for pitch. Two subjects had to match in pitch, repeatedly and as accurately as possible, a pure tone with an adjustable frequency and a pure tone whose frequency was fixed at 0.5, 2, 3.7 or 6.25 kHz. The two tones had either the same intensity or different intensities, our aim being to assess the effect of this variable on the accuracy (i.e. the standard deviation) of the frequency adjustments. On the basis of the hypothesis according to which frequency discrimination relies on temporal information up to 5 kHz and on tonotopical information beyond 5 kHz, we predicted that the effect of an intensity difference on subjects1 accuracy would be larger above 5 kHz than below. Our data show that for any standard frequency, introducing an intensity difference deteriorates accuracy only slightly (by less than a factor of 2 for a 15 dB difference). Contrary to our prediction, the deterioration is not larger above 5 kHz than below. We conclude that this negative resuit does not unequwocally invalidate the above-mentioned hypothesis of the mechanisms of frequency discrimination. Key words: pitch, loudness, excitation patterns.Résumé Deux sujets avaient pour tâche d'égaliser en hauteur, répétitivement et le plus précisément possible, un son pur ajustable en fréquence et un son pur étalon dont la fréquence prenait différentes valeurs. Les deux sons avaient soit le même niveau d'intensité, soit des intensités différentes, le but de l'expérience étant d'évaluer l'effet de cette variable sur la précision (la dispersion) des ajustements. Il apparaît que, quelle que soit la fréquence du son étalon, l'introduction d'une différence d'intensité dégrade peu la précision (moins d'un facteur 2 pour une différence de 15 dB). Contrairement à ce que nous attendions, la dégradation n'est pas plus grande au-dessus de 5 kHz qu'au-dessous. Mots clés : hauteur tonale, sonie, pattern d'excitation.Demany Laurent, Lavenant Hélène. Effet d'une différence d'intensité sur la précision des ajustements dans une tâche d'égalisation des hauteurs tonales de deux sons purs. In: L'année psychologique. 1985 vol. 85, n°3. pp. 329-343

Nature versus nurture in the detection of sour notes

Culturally prominent musical scales such as the diatonic major scale make use of the simple frequency ratios 2:1, 3:2, and 4:3 between notes. Are these ratios intrinsically advantageous for the perceptual encoding of melodies? We trained 48 young adults to detect "sour notes" in isochronous melodies of pure tones based on various musical scales, including novel ones. Frequency ratio simplicity was manipulated in three experiments employing overall eight scales. On each trial, two successive melodies were presented. Melody 1 randomly ordered the notes defining a certain standard scale, in a randomly selected frequency range. Melody 2 was another random ordering of the same tones, with or without a 1-semitone error in one tone. Listeners had to indicate if melody 2 contained an error or not. The standard scale was fixed within each test session, and feedback was provided on each trial. At least 10 successive test sessions – more than 2000 trials, up to 5280 in some cases – were run for each standard scale. For most of the scales, including the diatonic major scale, practice largely improved performance. Performance was also systematically favored by frequency ratio simplicity. Crucially, the benefit of frequency ratio simplicity was not smaller at the end of practice, when for each scale performance was presumably optimal or nearly optimal, than in the initial test sessions. Thus, frequency ratio simplicity appeared to be intrinsically (i.e., naturally) advantageous, at odds with the idea that its benefit might stem from a musical acculturation process pre-existing to this study

The perceptual reality of tone chroma in early infancy

International audienc

Auditory Perception: Relative Universals for Musical Pitch

International audienc

Consequences of cochlear damage for the detection of interaural phase differences

Thresholds for detecting interaural phase differences ͑IPDs͒ in sinusoidally amplitude-modulated pure tones were measured in seven normal-hearing listeners and nine listeners with bilaterally symmetric hearing losses of cochlear origin. The IPDs were imposed either on the carrier signal alone-not the amplitude modulation-or vice versa. The carrier frequency was 250, 500, or 1000 Hz, the modulation frequency 20 or 50 Hz, and the sound pressure level was fixed at 75 dB. A three-interval two-alternative forced choice paradigm was used. For each type of IPD ͑carrier or modulation͒, thresholds were on average higher for the hearing-impaired than for the normal listeners. However, the impaired listeners' detection deficit was markedly larger for carrier IPDs than for modulation IPDs. This was not predictable from the effect of hearing loss on the sensation level of the stimuli since, for normal listeners, large reductions of sensation level appeared to be more deleterious to the detection of modulation IPDs than to the detection of carrier IPDs. The results support the idea that one consequence of cochlear damage is a deterioration in the perceptual sensitivity to the temporal fine structure of sounds

The perception of frequency peaks and troughs in wide frequency modulations

This work was concerned with the perception of “instantaneous pitch” in continuously frequency modulated sounds. In experiment 1, a 70-dB sinusoidal carrier, close to 1 kHz, was modulated by the exponential of periodic functions corresponding to the sum of a few sinusoids [e.g., sin(a)+sin(3a)]. Each modulation had a fundamental frequency (a/2 π) of 1.5 Hz and was symmetric on the dimensions of time and log frequency. Thirty listeners identified discrete melodic motifs within these stimuli. The pitches of the identified notes mainly corresponded to the local frequency maxima; generally, the local minima were not heard as auditory “events” (pitch singularities). A similar perceptual asymmetry was not observed for comparable sequences of discrete tones. In experiments 2-4, frequency difference limens were measured for the maxima and minima of continuous frequency modulations, using an adaptive forced-choice method. Sinusoidal carriers were modulated by the exponential of one cycle of a 5-Hz cosine function, starting at phase π or phase 0 and giving an overall frequency swing of about 0.5 oct. For maxima and minima around 1 kHz, frequency shifts of maxima were better detected than frequency shifts of minima, by an average factor of 2. Generally, this asymmetry did not decrease as a function of subjects’ training in the discrimination task, and was still present when frequency minima were given a 6-dB intensity advantage over frequency maxima. No explanation was found for the advantage of frequency maxima with respect to perceptual salience (experiment 1) or discriminability (experiments 2-4)