A Comparison of Recordings of Sentences and Spontaneous Speech: Perceptual and Acoustic Measures in Preschool Children’s Voices

Summary

A well-controlled recording in a studio is fundamental in most voice rehabilitation. However, this laboratory like recording method has been questioned because voice use in a natural environment may be quite different. In children’s natural environment, high background noise levels are common and are an important factor contributing to voice problems. The primary noise source in day-care centers is the children themselves. The aim of the present study was to compare perceptual evaluations of voice quality and acoustic measures from a controlled recording with recordings of spontaneous speech in children’s natural environment in a day-care setting. Eleven 5-year-old children were recorded three times during a day at the day care. The controlled speech material consisted of repeated sentences. Matching sentences were selected from the spontaneous speech. All sentences were repeated three times. Recordings were randomized and analyzed acoustically and perceptually. Statistic analyses showed that fundamental frequency was significantly higher in spontaneous speech (P < 0.01) as was hyperfunction (P < 0.001). The only characteristic the controlled sentences shared with spontaneous speech was degree of hoarseness (Spearman’s rho = 0.564). When data for boys and girls were analyzed separately, a correlation was found for the parameter breathiness (rho = 0.551) for boys, and for girls the correlation for hoarseness remained (rho = 0.752). Regarding acoustic data, none of the measures correlated across recording conditions for the whole group.

Introduction

In a clinical setting, problems related to voice function are routinely assessed by perceptual evaluations of voice quality.¹ The most common material for this assessment is a standardized recording, consisting of reading a text aloud, naming pictures or repeating sentences, and sustaining vowels depending on the patient’s population. The recordings are often carried out in a sound-treated booth aiming at high-quality recordings. Based on these recordings, a perceptual assessment of voice quality along different perceptual parameters is carried out.2, 3, 4 The result of the perceptual evaluation together with laryngeal status makes up the basis for decisions regarding intervention. Also, improvement in voice quality is one of the primary benchmarks against which treatment outcome is evaluated, commonly assessed by an evaluation along perceptual and acoustic parameters after completed intervention.

A dysfunctional voice may be a serious social and psychological problem for adults⁵ and children.6, 7 Many habits, including vocal habits, are probably established during childhood. Thus, undesirable vocal habits may originate during early childhood and continue into adult life.8, 9 This would point to the importance of voice research focusing on child’s voice and the treatment and prevention of voice disorders in children. This research also needs to include vocal behavior and vocal demands in children’s everyday life.

Recently, the importance of in situ recordings of natural vocal behavior in everyday life situations has been pointed out.10, 11, 12, 13 In a study of preschool teachers’ voices, Södersten et al¹⁴ compared mean fundamental frequency (F₀) in a controlled recording to the F₀ in the spontaneous speech during work. They found that the mean F₀ was higher in the work-related recording compared with the controlled condition, indicating that a controlled recording may not reflect mean F₀ in spontaneous speech under natural conditions. There are few studies of children’s voice use in a natural setting. In a recent study of mean F₀ in children’s and teachers’ voices in a preschool setting, the results showed a significant difference for both children and adults between the recordings of sentences compared with real work/play situations.¹⁵ The findings support the conclusion that controlled setups are not suitable to evaluate F₀ values in a natural setting. These findings have also been supported by two studies of preschool-aged children, a case study of a 5-year-old boy¹⁶ and a study comparing F₀ in children at play compared with structured situations.¹⁷ The results indicate that studio recordings in a clinical setting need to be complemented by recordings in real-life situations and environments to correctly assess habitual F₀ in children.

The question asked in the present study is, does this difference in vocal behavior regarding F₀ also apply to other aspects of voice? Thus, children’s voice quality, mean F₀, and perturbation in a controlled recording were compared with sentences obtained during regular activities at the day-care center (DCC).