  We consider gauge/gravity duality with flavor for the finite-temperature
field theory dual of the AdS-Schwarzschild black hole background with embedded
D7-brane probes. In particular, we investigate spectral functions at finite
baryon density in the black hole phase. We determine the resonance frequencies
corresponding to meson-mass peaks as function of the quark mass over
temperature ratio. We find that these frequencies have a minimum for a finite
value of the quark mass. If the quotient of quark mass and temperature is
increased further, the peaks move to larger frequencies. At the same time the
peaks narrow, in agreement with the formation of nearly stable vector meson
states which exactly reproduce the meson mass spectrum found at zero
temperature. We also calculate the diffusion coefficient, which has finite
value for all quark mass to temperature ratios, and exhibits a first-order
phase transition. Finally we consider an isospin chemical potential and find
that the spectral functions display a resonance peak splitting, similar to the
isospin meson mass splitting observed in effective QCD models.
