Perception of everyday sounds: a developmental study of a free sorting task

Abstract

Objectives: The analysis of categorization of everyday sounds is a crucial aspect of the perception of our surrounding world. However, it constitutes a poorly explored domain in developmental studies. The aim of our study was to understand the nature and the logic of the construction of auditory cognitive categories for natural sounds during development. We have developed an original approach based on a free sorting task (FST). Indeed, categorization is fundamental for structuring the world and cognitive skills related to, without having any need of the use of language. Our project explored the ability of children to structure their acoustic world, and to investigate how such structuration matures during normal development. We hypothesized that age affects the listening strategy and the category decision, as well as the number and the content of individual categories.

Design: Eighty-two French children (6-9 years), 20 teenagers (12-13 years), and 24 young adults participated in the study. Perception and categorization of everyday sounds was assessed based on a FST composed of 18 different sounds belonging to three a priori categories: non-linguistic human vocalizations, environmental sounds, and musical instruments.

Results: Children listened to the sounds more times than older participants, built significantly more classes than adults, and used a different strategy of classification. We can thus conclude that there is an age effect on how the participants accomplished the task. Analysis of the auditory categorization performed by 6-year-old children showed that this age constitutes a pivotal stage, in agreement with the progressive change from a non-logical reasoning based mainly on perceptive representations to the logical reasoning used by older children. In conclusion, our results suggest that the processing of auditory object categorization develops through different stages, while the intrinsic basis of the classification of sounds is already present in childhood.

Fig 1. Distribution of the center of gravity of the sounds and frequency bands, ranging by frequency from low to high (scaled in log to base 10).

Circles represent non-linguistic human vocalizations, square musical instruments, and diamond environmental sounds.

Fig 2. Average number of sounds listening as a function of age and of the a priori category.

There are a significant differences between age groups and categories.

Fig 3. Average number of classes as a function of age of the participants.

Standard deviations are depicted for each age group. Significant differences between age groups are represented by the brackets and astericks (representing p<.05).

Fig 4. Illustration of the two main central partitions performed by participants, independent of the age.

Fig 5. Proportions of Central Partitions 1 and 2 performed by the subjects according to their age.

The other types of partitions have been grouped together (labeled “Others Partitions”).

Fig 6. Additive trees showing both similarity and differences across sounds as function of age.

The shorter is the line connecting two sounds, the more the sounds are judged similar.