ISMA-Vn

BACKGROUND

Nasalization and the processes involved in it across languages are phenomena studied in various fields, such as signal processing, acoustics, phonetics, phonology, dialectology, and historical linguistics. However, these disciplines do not always overlap, even though experts agree that nasalization is a dynamic and complex phenomenon whose linguistic, physical, and physiological mechanisms remain poorly understood. The acoustic structure of nasal vowels and consonants complicates the search for perceptual correlates of nasality, despite its importance in phonology: it is present in 97% of the world’s consonant inventories, and more than one in five languages distinguishes between oral and nasal vowels.

Acoustic studies of nasal sounds are of major scientific interest. Current models involve acoustic coupling between the oral and nasal passages, generating a complex spectrum composed of peaks and troughs. This coupling depends both on the shape of the passages and on the position of the soft palate, which can articulatorily connect the nasal and oral cavities without necessarily leaving an identifiable trace in the acoustic signal. Furthermore, the amplitude of the soft palate movement is greater for nasal vowels than for nasal consonants in French. Despite these models, the complexity of the resulting spectra makes it difficult to provide a precise explanation of the acoustic structure of nasal productions. Developing a relevant method to characterize these spectra is essential for better understanding the emergence, realization, evolution, perception, and categorization of nasal vowels.

In a previous study, Feng and Kotenkoff (2006) used a device capable of isolating the oral and nasal outlets separately during the production of nasal sounds. This device showed that the oral outlet remained primarily “oral” even during nasal production, changing as the soft palate lowered, while the nasal outlet was characterized by the physical properties of the pharyngo-nasal passage despite the coupling of the two passages.

GOING THE EXTRA MILE WITH THE SUPPORT OF LABEX CerCoG

The ISMA-Vn project fits into this context by aiming to use an improved version of Feng’s device to record nasal and oral outputs separately during nasal speech production. A corpus of recordings will be compiled from ten French-speaking speakers in a laboratory under controlled conditions. These data will enable the comparison of acoustic models with actual recordings by comparing the modeled transfer function of the oral output with the recording of the oral output alone, and similarly for the nasal output.

This approach will validate an acoustic model of nasal sounds and shed light on the complex concept of acoustic coupling, which remains a subject of extensive debate within the scientific community. In addition, a perceptual study involving approximately twenty native speakers will be conducted to analyze the phonological categorization of separate nasal and oral signals, thereby validating the acoustic-perceptual correlates of nasal sounds.

The support of LabEx CerCoG crucial to the success of this innovative project, which aims to advance our understanding of nasalization phenomena through a rigorous methodology that combines modeling, experimental recording, and perceptual analysis.