# Real-Time Visual Feedback in Singing Pedagogy: Current Trends and Future Directions
###### Abstract  
Singing pedagogy has increasingly adopted guide awareness through the use of meaningful real-time visual feedback. Technology typically used to study the voice can also be applied in a singing lesson, aiming at facilitating students' awareness of the three subsystems involved in voice production--breathing, oscillatory and resonator--and their underlying physiological, aerodynamical and acoustical mechanisms. Given the variety of real-time visual feedback tools, this article provides a comprehensive overview of such tools and their current and future pedagogical applications in the voice studio. The rationale for using real-time visual feedback is discussed, including both the theoretical and practical applications of visualizing physiological, aerodynamical and acoustical aspects of voice production. The monitorization of breathing patterns is presented, displaying lung volume as the sum of abdominal and ribcage movements signals. In addition, estimates of subglottal pressure are visually displayed using a subglottal pressure meter to assist with the shaping of musical phrases in singing. As to what concerns vibratory patterns of the vocal folds and phonatory airflow, the use of electrolgottography and inverse filters is applied to monitor the phonation types, voice breaks, pitch and intensity range of singers of different music genres. These vocal features, together with intentional voice distortions and intonation adjustments, are also displayed using spectrographs. As the voice is invisible to the eye, the use of real-time visual feedback is proposed as a key pedagogical approach in current and future singing lessons. The use of such an approach corroborates the current trend of developing evidence-based practices in voice education. s 30 September 20220 October 20220 October 20220 October 20220 October 20220 October 20220 October 20220 October 20220 October 20220 October 20220 October 20220 October 20220 October 20220 October 20220 October 20220 October 20220 October 2022020 October 20220202020220220220220  
The human voice, unlike any other musical instrument, is hidden to the eye [2; 9]. Therefore, one may argue that modification of neuromuscular behavior in 'voice building', which pertains to the pedagogical responsibilities of singing teachers, should not be limited to or solely based on personal experience [10; 11; 12]. Singing requires motor learning, which is facilitated by a knowledge of processes and procedures [13; 14], resulting in two types of responses: (i) knowledge of performance (KP) or, in other words, knowledge of how the body develops and acts; and (ii) knowledge of results (KR), that is, the outcomes associated with a particular bodily action [9; 15]. KR is of particular interest for the developing singer, as it leads to the promotion of self-regulation, increased motivation to practice and neuromotor improvement, provided that the offered feedback was objective, positive, instructive, task-orientated and meaningful [9; 16]. Real-time visual feedback in singing assists with the acquisition of KR by establishing effective biomechanical behavior based on meaningful visual information [4; 16; 17]. When combined with verbal instruction, it has been proven to be effective in the training of particular singing skills, such as intonation [16; 18]. Providing a direct visualization of the singer's vocal response to a given instruction helps circumvent \"critical points\" commonly observed in more traditional voice teaching models. In these models, the student needs to wait and process the verbal instruction of the teacher before attempting a subsequent vocal response [16; 19]. The increasing number of technological tools that provide real-time visual feedback of the voice justifies a comprehensive overview and discussion of their possible current and future pedagogical applications.