1. Distributions of cross-correlation coefficients between concurrent D call audio and tri-axial accelerometer signals.
Distributions of cross-correlation coefficients between concurrent D call audio and tri-axial accelerometer signals. Normalized peak coefficients from the cross-correlation of concurrent audio and accelerometer (accel.) signals as a function of call amplitude. (A) x-axis; (B) y-axis; (C) z-axis. (D) Histogram of the maximum cross-correlation coefficient values across the three axes for each D call. A bimodal distribution separates calls into those that do and those that do not register detectable accelerometer signals. In all four panels, dashed lines at coefficient values of 0.25 indicate the minimum threshold identified for an audio signal to be associated with a detectable acceleration signal. Many D calls only registered associated signals on a subset of the accelerometer's three orthogonal axes.
Mark R. Saddler et al. J Exp Biol 2017;220:
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