Perception of lateral misarticulation and its physical correlates

Area of Science:

• Speech Science
• Acoustic Phonetics
• Linguistics

Background:

• Lateral misarticulation (LM) is a speech sound disorder affecting pronunciation.
• Understanding the acoustic properties of LM is crucial for diagnosis and therapy.
• The relationship between listener perception and physical correlates of LM requires further clarification.

Purpose of the Study:

• To investigate the link between perceptual judgments of lateral misarticulation (LM) and its physical acoustic correlates.
• To identify specific spectral envelope features in speech that contribute to the perception of LM.

Main Methods:

• Three experiments were conducted using sustained speech sounds.
• Experiment 1: Compared spectral envelopes of normal speech (NS) and LM speech.
• Experiment 2: Assessed listener perception of NS and LM with manipulated spectral bands.
• Experiment 3: Estimated speech spectra using vocal tract area functions.

Main Results:

• LM speech exhibits flattened or decreasing spectral envelopes above 4 kHz, with a notable time-varying peak around 3.2 kHz.
• Replacing normal speech spectral bands (2.5–4.5 kHz) with those from LM significantly increased perceived LM.
• Acoustic peaks in LM appear related to vocal tract constriction length and position.

Conclusions:

• The spectral envelope characteristic around 3.2 kHz is a significant perceptual correlate of lateral misarticulation.
• Vocal tract shape and constriction dynamics play a role in generating the acoustic features of LM.