Speech Adjustments for Room Acoustics and Their Effects on Vocal Effort

The aims of the present study are (1) to analyze the effects of the acoustical environment and the voice style on time dose (D_{t_p}) and fundamental frequency (mean f₀ and standard deviation std_f₀) while taking into account the effect of short-term vocal fatigue and (2) to predict the self-reported vocal effort from the voice acoustical parameters.

Ten male and ten female subjects were recorded while reading a text in normal and loud styles, in three rooms-anechoic, semi-reverberant, and reverberant-with and without acrylic glass panels 0.5 m from the mouth, which increased external auditory feedback. Subjects quantified how much effort was required to speak in each condition on a visual analogue scale after each task.

(Aim1) In the loud style, D_{t_p}, f₀, and std_f₀ increased. The D_{t_p} was higher in the reverberant room compared to the other two rooms. Both genders tended to increase f₀ in less reverberant environments, whereas a more monotonous speech was produced in rooms with greater reverberation. All three voice parameters increased with short-term vocal fatigue. (Aim2) A model of the vocal effort to acoustic vocal parameters is proposed. The sound pressure level contributed to 66% of the variance explained by the model, followed by the f₀ (30%) and the modulation in amplitude (4%).

The results provide insight into how voice acoustical parameters can predict vocal effort. In particular, it increased when SPL and f₀ increased and when the amplitude voice modulation decreased.