  The spectra of gravitational waves from black hole evaporation generically
peak at frequencies of order the Hawking temperature, making this signal
ultra-high frequency for primordial black holes evaporating in the early
universe. This motivates us to consider small black holes in theories with
large extra dimensions, for which the peak frequency can be lowered
substantially, since the true bulk Planck scale $M_*$ can be much smaller than
the effective $M_{\rm Pl}$. We study the emission of brane-localized gravitons
during the Hawking evaporation of ultra-light primordial black holes in the
context of theories with large extra dimensions, with the ultimate goal of
computing the contribution to the stochastic gravitational wave background. To
accurately model black hole evolution, we compute greybody factors for all
particle species emitted on the brane and in the bulk, presuming the majority
of emission proceeds during the Schwarzschild phase. We then compute the power
spectrum and present day spectral density parameter for brane-localized
gravitons contributing to a gravitational wave signal. We find that for an
optimal choice of parameters, the peak frequency plateaus in the sub-MHz
regime, within range of planned high-frequency gravitational wave detectors,
making this scenario a target for detection once their sensitivity exceeds
$\Delta N_{\rm eff}$ bounds.
