Quantifying Vocal Repertoire Tessituras Through Real-Time Measures

Abstract

Introduction: Voice teachers use anecdotal evidence and experience in determining the appropriateness of repertoire for each student's development. Tessitura is important in that determination, but until recently a straightforward, repeatable, and quantifiable method for determining tessitura has not existed. However, technology exists to provide the means to estimate the tessituras of standard vocal repertoire by measuring sung pitch (fundamental frequency) and vocal dose (amount of phonation) in real-time performance.

Purpose: The purpose of this study was to examine the combined use of tessituragrams, Voice Range Profiles (VRPs), a singer's self-perception of a performance, and expert listeners perception of a performance towards the goal of a more systematic way of selecting appropriate voice repertoire for singers. The following research questions guided this investigation: 1) How do Performance Range Profiles (PRPs, performance-based tessituragrams computed from neck skin surface vibration during singing), compare to score-based tessituragrams of the same selection in the same key? 2) How do PRPs of the same vocal score compare when performed in three different keys? 3) How do singer VRPs compare with PRPs of three performances of a score, each sung in a different key? and 4) How do singer and expert panel perceptions of the selection's "fit" in three different keys compare with the alignment of each singer's VRP to their PRPs? Four female singers and five expert voice pedagogues were enlisted to address these questions.

Results: The distribution (histogram) of the score-based tessituragram closely matched the distribution of performance-based tessituragrams (PRP), suggesting that score-based tessituragrams have promise in accurately reflecting the performance-based tessitura of a musical vocal work. Acquired data revealed relationships of practical importance between score-derived tessituragrams, PRPs, acquired VRPs, and singer perceptions of ease in singing. These data suggest that score-based tessituragrams aligned with singer VRPs show promise in repertoire selection. However, there was only a minor relationship between expert panel perceptions of ease in singing and the acquired PRPs or singer perceptions of ease. Creation of a score-based tessituragram database could be combined with singer VRPs to assist in appropriate repertoire selection.

Keywords: Tessitura—Tessituragram—Voice Range Profile—Vocal dose—Voice dosimetry.

Figure 1.

Example of a Voice Range Profile (VRP) acquired with a voice dosimeter. For each sung pitch, the full vocal intensity range is shown.

Figure 2.

Score-based tessituragram. (a) Expected Dt by pitch in the key of Am. (b) Expected Dc by pitch in the key of Am. In this figure, fo is presented in half-step notes which also correspond to semitones (st, with 12 semitones per octave).

Figure 3.

(a) Dosimeter device, including a Roland RO-5 digital audio recorder and the collar of the Sonovox VoxLog dosimeter. (b) Sonovox VoxLog Collar with embedded accelerometer.

Figure 4.

Dosimeter-derived tessituragram of “Il mio bel foco…Quella fiamma”

Figure 5.

Creation of the PRP from accelerometer data. (a) A scatterplot of vocal intensity (dB SPL) and fo (st). (b) A 3-D histogram plotting number of occurrences of intensity and fo. (c) Contour map created from the elevations of the above 3-D histogram (b) treating the number of dB and fo occurrences like an elevation; concentric lines of a uniform color represent elevation, where the inner circles indicate higher occurrences of pitches and sound pressure levels. (d) A replot of (a) with the blue contour enclosing 68.2% of dB and fo phonation occurrences during the song performance (+/−1 standard deviation); the area of the contour can be represented in terms of an area (semitone x dB).

Figure 6.

Example of the Visual Analog Scale (100mm) completed by singers and expert panel members after each song repetition.

Figure 7.

(a) Performance Dt and Rt – Score-based vs. dosimeter reading. (b) Cycle dose (Dc) of Performances – Score-Based vs. Dosimeter Reading.

Figure 7.

(a) Performance Dt and Rt – Score-based vs. dosimeter reading. (b) Cycle dose (Dc) of Performances – Score-Based vs. Dosimeter Reading.

Figure 8.

(a) Singer 1 – dB SPL VRP area overlayed with SRP areas. (b) Singer 2 – dB SPL VRP area overlayed with SRP areas. (c) Singer 3 – dB SPL VRP area overlayed with SRP area. (d) Singer 4 – SPL VRP overlayed with SRP Area.

Figure 8.

(a) Singer 1 – dB SPL VRP area overlayed with SRP areas. (b) Singer 2 – dB SPL VRP area overlayed with SRP areas. (c) Singer 3 – dB SPL VRP area overlayed with SRP area. (d) Singer 4 – SPL VRP overlayed with SRP Area.

Figure 9.

Singer Perception vs Panel Perception – Average of All Questions

Figure 10.

Singer 1 (17-yo Soprano) a) Self Perception; b) Expert Panel Perception. A higher number indicates less perceived ease in singing.

Figure 11.

Singer 2 (18yo Soprano) a) Self Perception; b) Expert Panel Perception. A higher number indicates less perceived ease in singing.

Figure 12.

Singer 3 (21ys Mezzo) a) Self Perception; b) Expert Panel Perception. A higher number indicates less perceived ease in singing.

Figure 13.

Singer 4 (37yo Soprano) a) Self Perception; b) Expert Panel Perception. A higher number indicates less perceived ease in singing.