  We perform a high precision measurement of the spectrum of the QCD flux tube
in three-dimensional $\SU(2)$ gauge theory at multiple lattice spacings. We
compare the results at large $q\bar{q}$ separations $R$ to the spectrum
predicted by the effective string theory, including the leading order boundary
term with a non-universal coefficient. We find qualitative agreement with the
predictions from the leading order Nambu-Goto string theory down to small
values of $R$, while, at the same time, observing the predicted splitting of
the second excited state due to the boundary term. On fine lattices and at
large $R$ we observe slight deviations from the EST predictions for the first
excited state.
