Comparison of acoustic features due to the Lombard effect in typically developing children and adults

The Lombard effect is an involuntary response to speakers' experiences in the presence of noise during voice communication. This study aimed to investigate the Lombard effect by comparing the acoustic features of children and adults under different listening conditions. Twelve male children (5–9 years old) and 12 young adult men (24–35 years old) were recruited to produce speech under three different listening conditions (quiet, noise-55 dB, noise-70 dB). Acoustic analyses were then carried out to characterize their acoustic features, such as F0, intensity, duration, and vowel space area, under the three listening conditions. A Lombard effect was observed in the intensity and duration for children and adults who participated in this study under adverse listening conditions. However, we did not observe a Lombard effect in the F0 and vowel space areas of either group. These findings suggest that children can adjust their speech production in challenging listening conditions as much as adults.