Prosodic-Acoustic and Perceptual Analyses of Vocal Expressiveness in Emergency Call Center Operators: A Pilot Study

Emergency call center operators perform an essential public service and use their voices as a primary work tool. Their tasks include gathering critical information from callers and forwarding it to the sectors responsible for emergency response. This pilot study investigated vocal expressiveness in real emergency call center speech, focusing on perceived empathic stance and prosodic-acoustic characteristics.

Four real emergency call samples produced by two male and two female operators from an emergency call center in João Pessoa, Paraíba, Brazil, were analyzed through a perceptual experiment with 113 lay listeners and an exploratory prosodic-acoustic analysis performed in Praat using SpeechRhythmExtractor. Lay listeners rated the samples using semantic differential scales comprising five adjective pairs related to interpersonal stance, clarity, and perceived service effectiveness. Prosodic-acoustic parameters were examined through exploratory within-corpus comparisons across the four operator samples.

Listener ratings varied across the four operator samples, with TOpM01 receiving the most favorable overall ratings and TOpM02 the least favorable. Ratings also differed according to listener sex, with female listeners tending to assign less favorable scores in this sample. The acoustic analysis showed within-corpus variability in f0-related and modulation measures, low-frequency LTAS, Jitter, Shimmer, HNR, speech rate, and articulation rate. Descriptive comparison of the perceptual and acoustic findings suggested sample-specific correspondences in prosodic-acoustic profiles.

Lay listeners perceived differences in vocal expressiveness and empathic stance across real emergency call samples, and these impressions showed descriptive alignment with prosodic-acoustic profiles. However, the findings do not indicate that individual acoustic parameters determine perceived empathy. The quality of operators' vocal communication may affect users' experience during emergency-service interactions, with listener judgments potentially reflecting the interaction of vocal, semantic, pragmatic, interactional, and contextual information. These exploratory findings support larger studies designed to clarify the contribution of vocal expressiveness to perceived empathy and communicative effectiveness in emergency contexts.