  We present a concrete realization of the sound speed resonance (SSR)
mechanism for primordial black hole (PBH) formation within a specific model of
Dirac-Born-Infeld (DBI) inflation. We perform a perturbative approach to
phenomenologically construct such a viable DBI inflation model that involves
the nonoscillating stage and the oscillating stage, with a type of specific
forms of the warp factor and the potential. We show that the continuous but
nonsmooth conjunction of sound speed between two stages does not yield manifest
effects on the phenomenology of SSR, and thus, our model gives rise to the same
PBH mass spectrum as the original predictions of SSR. Additionally, we also
demonstrate that the violation of adiabaticity of the Mukhanov-Sasaki equation
does not affect the comoving curvature perturbation after Hubble crossing in
the nonresonant region. Making use of observational data, we derive various
cosmological constraints on the parameter space. Our analyses show that the
predicted tensor-to-scalar ratio is typically small, while the amplitude of
primordial non-Gaussianity can meet with cosmic microwave background bounds,
and additionally, the consistency relation for single-field slow-roll inflation
is softly violated in our case due to the small sound speed variations.

Cosmology and Nongalactic Astrophysics;General Relativity and Quantum Cosmology;High Energy Physics - Phenomenology;High Energy Physics - Theory