Auditory Proprioceptive Integration: Effects of Real-Time Kinematic Auditory Feedback on Knee Proprioception

Abstract

The purpose of the study was to assess the influence of real-time auditory feedback on knee proprioception. Thirty healthy participants were randomly allocated to control (n = 15), and experimental group I (15). The participants performed an active knee-repositioning task using their dominant leg, with/without additional real-time auditory feedback where the frequency was mapped in a convergent manner to two different target angles (40 and 75°). Statistical analysis revealed significant enhancement in knee re-positioning accuracy for the constant and absolute error with real-time auditory feedback, within and across the groups. Besides this convergent condition, we established a second divergent condition. Here, a step-wise transposition of frequency was performed to explore whether a systematic tuning between auditory-proprioceptive repositioning exists. No significant effects were identified in this divergent auditory feedback condition. An additional experimental group II (n = 20) was further included. Here, we investigated the influence of a larger magnitude and directional change of step-wise transposition of the frequency. In a first step, results confirm the findings of experiment I. Moreover, significant effects on knee auditory-proprioception repositioning were evident when divergent auditory feedback was applied. During the step-wise transposition participants showed systematic modulation of knee movements in the opposite direction of transposition. We confirm that knee re-positioning accuracy can be enhanced with concurrent application of real-time auditory feedback and that knee re-positioning can modulated in a goal-directed manner with step-wise transposition of frequency. Clinical implications are discussed with respect to joint position sense in rehabilitation settings.

Keywords: coordination; joint position sense; perception; rehabilitation; sonification.

Figure 1

Absolute mean and standard error of repositioning error (°) for the control, experimental group I (Dotted line represents control group. Darkened black line represents experimental group I, T: Proprioceptive test without auditory feedback, RT: Real-time auditory feedback, MAP: Acoustic mapping, CT: Control group, EXP: Experimental group). ^*Represents significant differences.

Figure 2

Constant mean and standard error of repositioning error (°) for the control, experimental group I (Dotted line represents control group. Darkened black line represents experimental group I, T: Proprioceptive test without auditory feedback, RT: Real-time auditory feedback, MAP: Acoustic mapping, CT: Control group, EXP: Experimental group). ^*Represents significant differences.

Figure 3

Absolute mean and standard error of repositioning error (°) for the control and experimental group II (Dotted line represents control group. Darkened black line represents experimental group II, T: Proprioceptive test without auditory feedback, RT: Real-time auditory feedback, MAP: Acoustic mapping, CT: Control group, EXP: Experimental group). ^*Represents significant differences.

Figure 4

Constant mean and standard error of repositioning error (°) for the control, and experimental group II. (Dotted line represents control group. Darkened black line represents experimental group I, gray line represents experimental group II, T: Proprioceptive test without auditory feedback, RT: Real-time auditory feedback MAP: Acoustic mapping step-down 0.25/rep for exp I, 1.3/rep for exp II, CT: Control group, EXP: Experimental group). ^*Represents significant differences.

Figure 5

Constant mean and standard error of repositioning error (°) for the experimental II, 2nd and 4th block, also for episodes (1–3). Difference in proprioceptive perceptions in between decomposed mapping conditions have been described for 5 sub-groups i.e., RT: real-time auditory feedback, sub-group I (G I: 40°: under-over-under, 75°: over-under-over), sub-group II (G II: 40°: over-under-over, 75°: over-under-over), sub-group III (G III:40°: over-under-over, 75°: under-over-under), and sub-group IV (G IV: 40°: under-over-under, 75°: under-over-under), and across 3 treatment blocks. The values on left represent 40°, and right 75° (RT: Real-time kinematic auditory feedback). ^*Represents significant differences.

Figure 6

Constant mean and standard error of the repositioning error (°) for the experimental II, 4th block, the values of transposition are normalized, and step-up transpositions have been multiplied with −1 to allow the direction of transposition to be similar for all three blocks. Mean values across the 2 angles for episodes (1–3). ^*Represents significant differences.