Raw EMG data and applied stimuli during each condition (SVS, MVS-S, MVS-4 and MVS-L).

<p>A: 2.5 s of raw data depicting muscle EMG (r-mGAS) and anterior-posterior directed force (+ve anterior). B: 2.5 s of applied stimuli and power spectra for each of the stimulus conditions. Circles in MVS plots represent exact frequencies chosen to be included in each signal. SVS, stochastic vestibular stimulation; MVS, multisine vestibular stimulation; r-mGAS, right medial gastrocnemius; AP, anterior-posterior.</p

Pooled (n = 8) cumulant density estimates.

<p>Responses indicate a biphasic response for both the stimulus-EMG (top plot) and stimulus-AP force estimates (bottom plot).</p

Reported psychophysical measures of intensity, unpleasantness and imbalance using visual analogue scales.

<p>Error bars are the standard error (n = 8). *  = P<0.05, **  = P<0.01, ***  = P<0.001 indicate significant differences as obtained from the pairwise comparison of SVS and all MVS stimulus conditions using a Bonferroni correction for multiple comparisons.</p

Assessment of system linearity using EMG and AP force data.

<p>A: pooled (n = 8) power spectrum of EMG (top plots) and AP force (bottom plots) during the MVS-4 stimulus condition. Power at even and odd harmonic frequencies are similar to power at non-harmonic frequencies. B: nonlinear distortion test during the MVS-4 stimulus condition. Significant nonlinear distortions are detected when points exceed the horizontal segmented line representing the significance level of the F-distribution (α = 0.05).</p

Coherence-, gain- and phase-frequency estimates of stimulus conditions for stimulus-EMG (top) and stimulus-AP force (bottom).

<p>A: pooled (n = 8) coherence plots for each stimulus condition. B: pooled (n = 8) gain plots for each stimulus condition. C: pooled (n = 8) phase plots for each stimulus condition. Gain and phase were plotted at frequencies with significant coherence and did not differ across stimulus conditions. Note the limited number of frequencies within the MVS-4 across the entire dynamic range and the limited number of frequencies in the MVS-L at high frequencies.</p

Summary of signal-to-noise ratios (SNR) and cumulant density responses across input stimuli.

<p>Cumulant density responses include the short and medium EMG and AP-force latencies and magnitudes for each of the input stimuli (mean ± SD, n = 8).</p