  We consider a holographic study of coupling dependent gravitational waves
produced by the cosmic first order QCD phase transition at finite baryochemical
potential. In the dual description, the first-order QCD phase transition
corresponds to the first-order Hawking-Page phase transition in Gauss-Bonnet
gravity. At intermediate coupling, we obtain key quantities characterizing the
gravitational wave energy density spectrum. We then find that the gravitational
waves might be detected for sufficiently large Gauss-Bonnet coupling, while
sound waves play an important role in the spectrum. We also consider a
supercooling scenario during the QCD phase transition and show that the
gravitational waves generated during this period can be detected by pulsar
timing array experiments.
