The Sensorimotor Mechanism Of Poor-pitch Singing And A Short-term Intervention Of Self-matching

Poor-pitch singing or vocal pitch imitation disorder(VPID)refers to a phenomenon in which an individual is unable to match a target pitch accurately.The overall prevalence of poor-pitch singing is around one third.Although disorders of pitch perception,sensorimotor integration,vocal motor controlling,or memory can lead to poor-pitch singing,the sensorimotor integration dysfunction is believed to be the major cause of poor-pitch singing.Previous research has systematically explored the sensorimotor mechanism of poor-pitch singing,but none of those studies investigated the construct of sensorimotor mapping system,and a model proposed previously did not well represent all types of pitch matching.In addition,existing explanations on the mechanism of self-imitation advantage that is a robust effect observed in the domain of pitch-singing need to be improved due to inaccuracy.Furthermore,there has no research focusing on the intervention of poor-pitch singing via the self-imitation advantage.This study aims to further explore the sensorimotor mechanism of poor-pitch singing and the intervention method of poor-pitch singing based on self-imitation.The study proposes the erroneous-missing mismapping hypothesis to depict the structure of sensorimotor mapping system in the categorical view.In the theory,sensorimotor mismapping can be categorized into two types:erroneous mapping and no mapping.Each of the two types of mismapping produces inaccurate pitch matching with unique characteristics.In addition,this study proposes a linear mapping model to describe the formation of sensorimotor mapping system.Finally,the study designed a self-imitation training system and used it to investigate whether a short-term self-imitation training could improve poor singers' pitch matching performance.The present study consists of the following seven studies.Study 1 and Study 2 tested the reliability and validity of operational definition of mismapping types.The two studies used the pure-tone imitation task and the same/different articulatory self-imitation tasks,where participants were asked to match target pitches as soon and accurately as possible.All reliability tests in three pitch-matching tasks revealed positive correlations between precision in two temporally divided sections,indicating that the operational definitions of the two types of mismapping have moderate reliability.The operational definition has good criterion-related validity:(1)pitch matching with no mapping is associated with longer response latencies than pitch matching with erroneous mapping;(2)phonation is more dependent on articulation precision with no mapping than with erroneous mapping.Additionally,Study 2 proposed and verified an explanation for the self-advantage in pitch matching,in which the author argued that articulation precision between the target and intended vocal action produces the self-advantage.Study 3 explored characteristics of mismapping in the continuum of precision of pitch matching.In this study,the criterion validity of operational definition of mismapping was tested by investigating whether there was linear relationship between precision of pitch matching and each of the two criteria(the self-advantage;the slope of regression line between the self-advantage and precision),respectively.The data indicated that the dependence of phonation on articulatory consistency was associated with the decrease of precision of pitch matching.The result replicated results of Study 1 and 2,further supporting the erroneous-missing hypothesis.Study 4 performed Monte Carlo simulations to address whether the differences in the linear relationship between the self-advantage and precision for the two types of mismapping observed in Study 2 and 3 were foregone conclusions.The results of Monte Carlo simulations,which revealed the difference in the linear relationship between the self-advantage and precision of pitch matching with the two types of mismapping,were in agreement neither with the prediction of the erroneous-missing hypothesis nor with our empirical data.The result suggests that the differences between the linear relationship between the self-advantage and precision with erroneous mapping and that with no mapping,observed in the previous pitch-matching tasks,can not be simply attributed to the statistical collinearity between the self-advantage and precision.Study 5 proposed a linear mapping model to explain the formation of sensorimotor mapping system.The result of model simulation showed that the model well represent all of four types of pitch matching observed in early literature as well as the study.Study 6 investigated whether a short-term intervention based on the self-imitation could improve the pitch matching performance of poor-pitch singers.The result indicated that the designed short-term self-imitation training improved poor-singers'performance.In addition,the intervention had the generalization effect on pitch and timbre.Furthermore,the effect of self-imitation training was larger on pitch matching with no mapping than on those with erroneous mapping.Study 7 investigated whether a short-term intervention based on the self-imitation could improve the pitch matching performance of poor-pitch singers with congenital amusia.The result indicated that the designed short-term self-imitation training improved poor-singers' performance.The following conclusions can be drawn from the present study.First,the sensorimotor mismapping that causes poor-pitch singing can be categorized into two types:erroneous mapping and no mapping.Erroneous mapping leads to inaccurate but precise pitch matching,while no mapping produces inaccurate and imprecise pitch matching.Pitch matching with no mapping is associated with longer response latencies than pitch matching with erroneous mapping.In addition,phonation is more dependent on articulation consistency with no mapping than with erroneous mapping.The conclusion is futher supported when investigating sensorimotor mismapping on a continuum of precision.That is,the dependency of pitch-singing on the articulation consistency between target tone and intended vocal production increases as the precision of pitch-singing decreases.Second,the formation of sensorimotor mapping can be depicted by the linear mapping model.The distortion of mapping by comfort pitch plays a crucial role in the formation of sensorimotor mapping system.The severity of dysfunction of sensorimotor mapping can be represented by the distortion of actual regression line from the perfect line.In addition,the linear mapping model well represents all of four types of pitch matching.Third,the self-imitation advantage results from articulation consistency.Based on this,the short-term self-imitation training to some extent improves the performance of poor-pitch singers(including congenital amusics).In addition,the intervention had generalization effects on pitch and timbre.Furthermore,the effect of self-imitation training was larger on pitch matching with no mapping than on those with erroneous mapping.