Acoustic spectral feedback in vocal learning: a systematic review of psychological mechanisms and skill outcomes

Abstract

Vocal skill acquisition is inherently “invisible”: learners cannot directly observe the movements of their vocal organs, so traditional instruction depends heavily on the teacher’s auditory judgment and metaphorical language. This leaves learners ill-equipped to detect errors and self-correct during independent practice. Spectral and acoustic visualization technologies—pitch-trajectory displays, spectrograms, formant analysis, and physiological biofeedback—can externalize this hidden process, yet systematic synthesis at the level of psychological mechanisms remains scarce. Using psychological mechanisms as its organizing framework, this review synthesizes the role of acoustic spectral feedback in vocal learning and seeks to bridge motor learning theory and self-regulated learning theory, which have not previously been integrated in this context. Following PRISMA 2020, we systematically searched WoS, Scopus, PsycINFO, ERIC, PubMed, and CNKI (2005–2025). Using thematic narrative synthesis, we classified the 36 included studies by psychological mechanism rather than by tool type; only 7 reported a formal mediation test. The evidence revealed five mechanism pathways. Spectral feedback is associated with self-efficacy gains attributed to accumulated mastery experience via knowledge of results (relatively strong). It promotes metacognitive monitoring by externalizing implicit mechanisms (strong for measurement, but the metacognition→skill test was null). It supports self-regulated learning through the plan–monitor–reflect cycle (moderate). Its effect on motivation and emotional engagement remains unverified (limited). Real-time concurrent feedback entails a cognitive-load versus guidance-dependency trade-off (moderate). Critically, 29 of 36 studies did not formally test the feedback→mechanism→skill pathway—the field’s most prominent methodological gap. A preliminary integrated pathway framework of acoustic spectral feedback in vocal learning is advanced as an interpretive proposition derived from the synthesized evidence rather than as an empirically verified mechanism, with evidence gaps and testable hypotheses annotated so as to scaffold future empirical research. Open Science Framework, https://osf.io/qgwxk , identifier qgwxk.