# Real-Time Visual Feedback in Singing Pedagogy: Current Trends and Future Directions
## 5 Conclusions  
The current article aimed at a comprehensive review of technological tools with pedagogical applications for the teaching of singing students. The benefits of the real-time  
Figure 19: Spectrograms of different intentional voice distortions displayed by Praat software. Four examples are presented: (**1**) irregular aperiodic phonation; (**2**) biphonation; (**3**) subharmonic phonation with a predominance of harmonic components; (**4**) subharmonic phonation with a predominance of noise components (adapted from [59] with authors’ permission). Figure 20: VoceVista Video Pro software display of a male singer practicing micro-intonation between pitches C4 and C#4, marked within the red box. visualization of physiological, aerodynamic and acoustical aspects of voice production in singing were discussed, especially concerning knowledge of results. As in physiological voice therapy programs, teaching singing can strive for the achievement of an aesthetic acoustical output grounded in the balance between the three subsystems of voice production--respiratory, oscillatory and resonator--which is a goal clearly facilitated by their visualization in real-time. The voice is a unique musical instrument, hidden to the naked eye. Therefore, teaching singing requires pedagogical approaches, among which guided awareness enhanced by meaningful feedback constitutes an example. The RespTrack system allows for the guided awareness of breathing patterns, crucial to control lung volume and, thus, the elasticity of the breathing apparatus and \(p_{\text{sub}}\). This physiological parameter controls SPL, a significant acoustical parameter for the perceived vocal loudness. Still related to the respiratory system, the use of \(p_{\text{sub}}\) meters in singing lessons were also discussed for the purposes of monitoring behaviors related to vocal health and musical phrasing. As to what concerns the oscillatory subsystem, the visualization of the vibratory patterns of the vocal folds helps master vocal fold tension, extension and adduction at different degrees of vocal loudness. Real-time visual feedback can be provided by means of an electroglottograph, electrolaryngograph and an inverse filter. Displays using these technologies allow for the visualization of phonation types and an understanding of associated voice qualities. The recent FonaDyn software also allows the display of voice maps, which is crucial to monitor vocal development and control glottal adduction at different pitches and intensities. Real-time visual feedback of adjustments of the resonator system can be provided by spectrographic displays. Several software can be used for this purpose, showing details of voice onset, intonation, legato, vibrato, ornamentations, synchronization between singing and piano accompaniment and formant tuning or de-tuning, according to the aesthetic requirements of the singing style. Voice breaks, phonation types, intentional voice distortions and intonation are other parameters relevant to voice quality and expressiveness in singing that can be displayed in real-time using spectrographic displays. Singing teachers have used spectrographic displays since the 1970s; such displays have become more accessible, are easy to handle and can be complemented by real-time visual feedback on breathing behaviors and vibratory patterns of the vocal folds during singing. We believe that, in the near future, the use of technology in singing lessons can become a gold standard for the development of effective pedagogical approaches. Singing pedagogy is already moving towards the development of science-based practices. Like any other musical instrument, the voice may be impaired by misuse; however, unlike other instruments, the voice cannot be replaced if 'ruined'. It is a teacher's pedagogical responsibility to guide the student in achieving individual vocal homeostasis simultaneously with the fulfilment of artistic expectations. This guidance greatly benefits from real-time visual feedback displays such as the ones reviewed here.