Application of free sorting tasks to sound quality experiments

Attention Perception & Psychophysics, 2007

Four experiments investigated the acoustical correlates of similarity and categorization judgments of environmental sounds. In Experiment 1, similarity ratings were obtained from pairwise comparisons of recordings of 50 environmental sounds. A three-dimensional multidimensional scaling (MDS) solution showed three distinct clusterings of the sounds, which included harmonic sounds, discrete impact sounds, and continuous sounds. Furthermore, sounds from similar sources tended to be in close proximity to each other in the MDS space. The orderings of the sounds on the individual dimensions of the solution were well predicted by linear combinations of acoustic variables, such as harmonicity, amount of silence, and modulation depth. The orderings of sounds also correlated significantly with MDS solutions for similarity ratings of imagined sounds and for imagined sources of sounds, obtained in Experiments 2 and 3—as was the case for free categorization of the 50 sounds (Experiment 4)—although the categorization data were less well predicted by acoustic features than were the similarity data.

The present work involved a sound-sorting and category-labelling task that elicits rather than prescribes words used to describe sounds, allowing categorization strategies to emerge spontaneously and the interpretation of the principal dimensions of categorization using the generated descriptive words. Previous soundscape work suggests that 'everyday listening' is primarily concerned with gathering information about sound sources, and that sounds are typically categorized by perceived similarities between the sound-causing events. The present work demonstrates that this is likely to be the case when sound-sources are sufficiently differentiated for this to be a useful cognitive strategy, such as when categorizing a variety of different sound sources, or when categorizing a broad class of sounds with multiple sources such as 'water'. However, distinct strategies based upon alternative cues emerge for other types of sounds. For example, categorization of dog sounds is primarily determined by judgements relating to perceptual dimensions similar to valence ('sad'/'lonely'-'playful'/'friendly') and arousal ('bored'/'whining'-'threatening'/'vicious'), a finding that supports the circumplex model of affect as a meaningful framework for understanding human categorization of this type of sound. Categorization of engine sounds on the other hand was found to be based primarily upon explicit assessment of the aco ustic signal, along dimensions which correlate strongly with the fluctuation strength ('steady'-'chugging') and sharpness ('muffled'-'jarring') of the recordings. These results demonstrate that categorization of sound is based upon different strategies depending on context and the availability of cues. It has implications for experimental methods in soundscapes that prescribe conceptual frameworks on test subjects. For instance, careful consideration should be given to the appropriateness of semantic differential scales in future perceptual soundscape work.

2018

Different musical instruments do not simply exhibit different musical timbres; they also evoke different phenomenological experiences, or "musical instrument qualia." Informal descriptions of instrument sounds seem to employ stereotypical characterizations, such as "airy" for a flute or "heavy" for a tuba. Previous research has sought to identify dimensions of timbre through listener judgments of paired comparisons (Grey, 1977, Kendall et al., 1999). Investigations into the semantic dimensions of timbre demonstrate that a number of descriptive terms map consistently onto particular acoustic correlates of timbre (e.g. Zacharkakis, Pastiadis, & Reiss, 2014). This three-part project aims to develop a model of the dimensions of musical instrument qualia. Results of the first two studies are reported here. In the first study, interviews were conducted with professional and semi-professional musicians in which they were asked to open-endedly describe the sounds of different musical instruments. Responses were subjected to content analysis using a pile-sort method, yielding an initial list of categories of musical instrument qualia. To test the reliability and usefulness of the dimensions yielded from the first study, the second study asked participants to rate musical instrument sounds according to the pile-sorted categories. Principal components analysis suggests ways in which categories with significant overlapping variance can be collapsed; preliminary results of this analysis are presented here. In the last stage of the study (not reported here), participants will rate an expanded number of instruments according to each of the dimensions in the final PCA model; these results will then be used to generate perceptual profiles for the most common Western musical instruments.

Joint Baltic-Nordic Acoustic Meeting, 2004

In this paper psychoacoustic distances, or perceived differences, within sounds that differ from each other in terms of musical timbre are studied. The sounds were modified in four timbre dimensions: the ratio of even and odd harmonic components, brightness, the attack time, and the amount of noise. The psychoacoustic distances between the sounds differing only in timbre were evaluated through a subjective listening test. A set of sounds having an equal psychoacoustic distance from the reference sound was generated for a ...

Studies in Second Language Acquisition

Our study proposes the use of a free classification task for investigating the dimensions used by listeners in their perception of nonnative sounds and for predicting the perceptual discriminability of nonnative contrasts. In a free classification task, participants freely group auditory stimuli based on their perceived similarity. The results can be used to predict discriminability and can be compared to various acoustic or phonological dimensions to determine the relevant cues for listeners. The viability of this method was examined for both a segmental contrast (German vowels) and a nonsegmental contrast (Finnish phonemic length). Perceptual similarity data from the free classification task accurately predicted discriminability in an oddity task and separately provided rich information on how the perceptual space is shaped. These results suggest that a free classification task and related analyses are informative and replicable methods for examining nonnative speech perception.

The Journal of the Acoustical Society of America, 2015

Influence of loudness on sound recognition was investigated in an explicit memory experiment based on a conscious recollectiontest phase-of previously encoded information-study phase. Three encoding conditions were compared: semantic (sounds were sorted in three different categories), sensory (sounds were rated in loudness), and control (participants were solely asked to listen to the sounds). Results revealed a significant study-to-test change effect: loudness change between the study and the test phases affects recognition. The effect was not specific to the encoding condition (semantic vs sensory) suggesting that loudness is an important hint for everyday sounds recognition.

The Journal of the Acoustical Society of America, 2008

The aim of the study is to transpose and extend to a set of environmental sounds the notion of sound descriptors usually used for musical sounds. Four separate primary studies dealing with interior car sounds, air-conditioning units, car horns, and closing car doors are considered collectively. The corpus formed by these initial stimuli is submitted to new experimental studies and analyses, both for revealing metacategories and for defining more precisely the limits of each of the resulting categories. In a second step, the new structure is modeled: common and specific dimensions within each category are derived from the initial results and new investigations of audio features are performed. Furthermore, an automatic classifier based on two audio descriptors and a multinomial logistic regression procedure is implemented and validated with the corpus.

Psychological Research-psychologische Forschung, 1995

To study the perceptual structure of musical timbre and the effects of musical training, timbral dissimilarities of synthesized instrument sounds were rated by professional musicians, amateur musicians, and nonmusicians. The data were analyzed with an extended version of the multidimensional scaling algorithm CLASCAL (Winsberg & De Soete, 1993), which estimates the number of latent classes of subjects, the coordinates of each timbre on common Euclidean dimensions, a specificity value of unique attributes for each timbre, and a separate weight for each latent class on each of the common dimensions and the set of specificities. Five latent classes were found for a three-dimensional spatial model with specificities. Common dimensions were quantified psychophysically in terms of log-rise time, spectral centroid, and degree of spectral variation. The results further suggest that musical timbres possess specific attributes not accounted for by these shared perceptual dimensions. Weight patterns indicate that perceptual salience of dimensions and specificities varied across classes. A comparison of class structure with biographical factors associated with degree of musical training and activity was not clearly related to the class structure, though musicians gave more precise and coherent judgments than did nonmusicians or amateurs. The model with latent classes and specificities gave a better fit to the data and made the acoustic correlates of the common dimensions more interpretable.

Perception & Psychophysics, 2007

A feature-based representation of auditory stimuli is proposed and tested experimentally. Within a measurement-theoretical framework, it is possible to decide whether a representation of subjective judgments with a set of auditory features is possible and how unique such a representation is. Furthermore, the method avoids confounding listeners' perceptual and verbal abilities, in that it strictly separates the process of identifying auditory features from labeling them. The approach was applied to simple synthetic sounds with well-defined physical properties (narrow-band noises and complex tones). For each stimulus triad, listeners had to judge whether the first two sounds displayed a common feature that was not shared by the third, by responding with a simple "yes" or "no." Because of the high degree of consistency in the responses, feature structures could be obtained for most of the subjects. In summary, the proposed procedure constitutes a supplement to the arsenal of psychometric methods with the main focus of identifying the type of sensation itself, rather than of measuring its threshold or magnitude.