  The collective modes of a quantum liquid shape and impact its properties
profoundly, including its emergent phenomena such as superfluidity. Here we
present how a two-dimensional Bose gas responds to a moving lattice potential.
In particular we discuss how the induced heating rate depends on the
interaction strength and the temperature. This study is motivated by the recent
measurements of Sobirey {\it et al.} arXiv:2005.07607 (2020), for which we
provide a quantitative understanding. Going beyond the existing measurements,
we demonstrate that this probing method allows to identify first and second
sound in quantum liquids. We show that the two sound modes undergo
hybridization as a function of interaction strength, which we propose to detect
experimentally. This gives a novel insight into the two regimes of Bose gases,
defined via the hierarchy of sounds modes.
