  We statistically investigate high-frequency whistler waves (with frequencies
higher than $\sim 10$ % of the local elect ron cyclotron frequency) at Earth's
bow shock using Magnetospheric Multi-Scale (MMS) spacecraft observations. We
focus specifically on the wave power within the shock transition layer, where
we expect electron acceleration via stochastic sh ock drift acceleration (SSDA)
to occur associated with efficient pitch-angle scattering by whistler waves. We
find that the wave power is positively correlated with both the Alfv\'en Mach
number in the normal incidence frame $M_{\rm A}$ and in the de Hoffmann-Teller
frame $M_{\rm A}/\cos \theta_{Bn}$. The empirical relation with $M_{\rm A}/\cos
\theta_{Bn}$ is compared with the theory of SSDA that predicts a threshold wave
power proportional to $(M_{\rm A}/\cos \theta_{Bn})^{-2}$. The result suggests
that the wave power exceeds the theoretical threshold for $M_{\rm A} / \cos
\theta_{Bn} \gtrsim 30-60$, beyond which efficient electron acceleration is
expected. This aligns very well with previous statistical analysis of electron
acceleration at Earth's bow shock (M. Oka, G eophys.~Res.~Lett., 33, 5, 2006).
Therefore, we consider that this study provides further support for SSDA as the
mechanism of electron acceleration at Earth's bow shock. At higher-Mach-number
astrophysical shocks, SSDA will be able to inject electrons into the diffusive
shock acceleration process for subsequent acceleration to cosmic-ray energies.
