Sabine Meunier

End level bias on direct loudness ratings of increasing sounds

Three experiments on loudness of sounds with linearly increasing levels were performed: global loudness was measured using direct ratings, loudness change was measured using direct and indirect estimations. Results revealed differences between direct and indirect estimations of loudness change, indicating that the underlying perceptual phenomena are not the same. The effect of ramp size is small for the former and important for the latter. A similar trend was revealed between global loudness and direct estimations of loudness change according to the end level, suggesting they may have been confounded. Measures provided by direct estimations of loudness change are more participant-dependent.

Additivity of nonsimultaneous masking for short Gaussian-shaped sinusoidsa)

The additivity of nonsimultaneous masking was studied using Gaussian-shaped tone pulses (referred to as Gaussians) as masker and target stimuli. Combinations of up to four temporally separated Gaussian maskers with an equivalent rectangular bandwidth of 600 Hz and an equivalent rectangular duration of 1.7 ms were tested. Each masker was level-adjusted to produce approximately 8 dB of masking. Excess masking (exceeding linear additivity) was generally stronger than reported in the literature for longer maskers and comparable target levels. A model incorporating a compressive input/output function, followed by a linear summation stage, underestimated excess masking when using an input/output function derived from literature data for longer maskers and comparable target levels. The data could be predicted with a more compressive input/output function. Stronger compression may be explained by assuming that the Gaussian stimuli were too short to evoke the medial olivocochlear reflex (MOCR), whereas for longer maskers tested previously the MOCR caused reduced compression. Overall, the interpretation of the data suggests strong basilar membrane compression for very short stimuli.

Comparative measurements of loudspeakers in a listening situation

Comparison of loudspeakers is a major concern during design or product selection. There are several standards for the measurement of loudspeaker characteristics, but none of them provides hints for a rigorous comparison between devices. In this study, different ways of evaluating acoustical dissimilarity between loudspeakers were compared. Several methods of signal analysis were used, and for each method a metric evaluating the dissimilarity between two signals was defined. The correlation between the different dissimilarity evaluations over a significant panel of loudspeakers led to identified classes of measurements. A specific aspect of this work is that measurements were performed in a standard listening environment, rather than in an anechoic or reverberant one. It allowed the use of the recorded signals for a simple listening test, providing a perceptual metric which was compared to the acoustical ones. It also allowed the introduction of auditory models in the computation of some acoustical metrics, so defining a new class of measurements which gave results close to the perceptual ones.

Identification of some perceptual dimensions underlying loudspeaker dissimilarities

This study investigated the dimensions underlying perceived differences between loudspeakers. Listeners compared the sound reproduction of 12 loudspeakers in a room, using three musical excerpts. For the loudspeakers to be compared one just after the other in exactly the same conditions, the sounds radiated by the loudspeakers were recorded in a listening room, and the recorded sounds were submitted to paired comparisons using headphones. The resulting perceptual dissimilarities were analyzed by using a multidimensional scaling technique, revealing two main perceptual dimensions used by listeners to discriminate the loudspeakers. These dimensions were identical for the three musical excerpts. As the signals heard by listeners were directly accessible, they were used to define acoustical attributes describing the perceptual dimensions. Instead of arbitrarily choosing one acoustical analysis to define these attributes, several analyses were compared. The temporal, spectral, and time-frequency domains were investigated, and different auditory models were tested. These auditory models allowed the best description of the differences perceived by listeners, and were used to define two acoustical attributes describing our perceptual dimensions: the bass/treble balance and the medium emergence.

Are Rising Sounds Always Louder? Influences of Spectral Structure and Intensity-Region on Loudness Sensitivity to Intensity-Change Direction

In a previous study, a robust asymmetry in global loudness was observed between rising and falling-intensity 1-kHz tones, pointing out the existence of a mechanism specifically sensitive to sound intensity direction [Ponsot et al., Attention Perception, & Psychophysics, 77(3), 907-920 (2015)]. The properties of this “direction-sensitive” mechanism are further explored in the present study, where its dependence on two stimulus characteristics, the spectral content and the intensity region is examined. In a first experiment, the global loudness of rising and falling-intensity sounds varying over 15dB ranges was assessed in a magnitude estimation task. The ramps had various spectral contents (pure tones from 250 Hz to 8 kHz and broadband noises) and were presented in different intensity-regions (from [50-65 dB SPL] to [70-85 dB SPL]). Significant asymmetries were observed across the different frequencies but not for broadband noises. In addition, a significant interaction between the direction of intensity-change and the region of intensity was observed for tones and noises. This latter effect was specifically addressed in a second experiment using an adaptive loudness-matching procedure, in which asymmetries were inferred from pairwise comparisons, both for 1-kHz tones and for white noises presented in mid and high intensity-regions. As in Exp. 1, greater asymmetries were observed for tones compared to noises; however significant asymmetries were found for noises as well. Furthermore, for both tones and noises, the size of the asymmetries was significantly decreased with the intensity-region when the sound pairs were composed of a falling followed by a rising stimulus. These results are discussed in the light of recent physiological and neuroscience studies showing that spectrally structured looming sounds are treated specially by the brain.

Rate discrimination at low pulse rates in normal-hearing and cochlear implant listeners: Influence of intracochlear stimulation sitea)

Temporal pitch perception in cochlear implantees remains weaker than in normal hearing listeners and is usually limited to rates below about 300 pulses per second (pps). Recent studies have suggested that stimulating the apical part of the cochlea may improve the temporal coding of pitch by cochlear implants (CIs), compared to stimulating other sites. The present study focuses on rate discrimination at low pulse rates (ranging from 20 to 104 pps). Two experiments measured and compared pulse rate difference limens (DLs) at four fundamental frequencies (ranging from 20 to 104 Hz) in both CI and normal-hearing (NH) listeners. Experiment 1 measured DLs in users of the (Med-El CI, Innsbruck, Austria) device for two electrodes (one apical and one basal). In experiment 2, DLs for NH listeners were compared for unresolved harmonic complex tones filtered in two frequency regions (lower cut-off frequencies of 1200 and 3600 Hz, respectively) and for different bandwidths. Pulse rate discrimination performance was significantly better when stimulation was provided by the apical electrode in CI users and by the lower-frequency tone complexes in NH listeners. This set of data appears consistent with better temporal coding when stimulation originates from apical regions of the cochlea.

Asymmetry in perceived duration between up-ramp and down-ramp sounds as a function of duration

The perceived duration of 1-kHz pure tones with increasing or decreasing intensity profiles was measured. The ratio between the down- and up-ramp durations at equal subjective durations was examined as a function of the sound duration (50, 100, 200, 500, 1000, 2000 ms). At 50 and 100 ms, the ratio was constant and equaled about 1.7, then it logarithmically decreased from 100 to 1000 ms to reach a constant value of 1 at 1 and 2 s. The different mechanisms proposed in the literature to explain the perceived duration asymmetry between up-ramp and down-ramp were discussed in the light of the dependence of this ratio on duration.

Auditory time-frequency masking: psychoacoustical data and application to audio representations

In this paper, the results of psychoacoustical experiments on auditory time-frequency (TF) masking using stimuli (masker and target) with maximal concentration in the TF plane are presented. The target was shifted either along the time axis, the frequency axis, or both relative to the masker. The results show that a simple superposition of spectral and temporal masking functions does not provide an accurate representation of the measured TF masking function. This confirms the inaccuracy of simple models of TF masking currently implemented in some perceptual audio codecs. In the context of audio signal processing, the present results constitute a crucial basis for the prediction of auditory masking in the TF representations of sounds. An algorithm that removes the inaudible components in the wavelet transform of a sound while causing no audible difference to the original sound after re-synthesis is proposed. Preliminary results are promising, although further development is required.

Additivity of auditory masking using Gaussian‐shaped tones

Both temporal and spectral masking have been studied extensively in the literature. Mostly, they have been regarded as separate phenomena. Very little is known about the interaction between these two effects, i.e. masking in the time‐frequency domain. Data on the time‐frequency spread of masking evoked by a single Gaussian‐shaped tone pulse are presented in an accompanying study at the same conference (Necciari et al.). The current study gathers data on the additivity of masking by up to four, approximately equally effective Gaussian maskers (ERB=600 Hz), separated either along the time or the frequency axis. For temporal separation, the amount of masking increases with the number of maskers, with excess masking (exceeding linear additivity) of up to 25 dB. For frequency separation (preliminary data) excess masking amounts up to 15 dB, and the higher‐frequency masker (relative to the target) contributes more to the additivity than the lower‐frequency maskers. Experiments with multiple maskers combining bo...

Detection of multicomponent signals: Effect of difference in level between components

The detection of multicomponent signals for which the components are not equidetectable is precisely investigated as a function of the level difference ΔL(i∕j) between components. The detection thresholds are determined for a seven-tone complex signal with random starting phases masked by white noise. Level differences between the components are examined. A model for non-equidetectable conditions based on the statistical summation model is described. The improvement in detection is calculated from the level difference between components that is related to the thresholds for single components. The model predictions are in accordance with the experimental results.