The iPhone 6 is still a decent modern iPhone, plenty fast enough for everyday use, and that's what lets the HomePod do all its fancy tricks, including all the processing required to hear you speak
at a normal volume even while the music is pumping.
It should be noted, however, that while a study on senescent cell ablation in genetically
normal mice would provide
at least some evidence on the effect of senescent cells (and their ablation) on promoting cancer,
even such a study would likely show less effect than could be anticipated in a large mammal model, since
even normally - aging mice rarely suffer metastatic disease to the extent of aging humans, as sheer primary tumor
volume is generally sufficient to be fatal to mice.
Even when music is playing loudly, it understands commands to change the color of lights, turn on plugs or fans, lock doors, etc. all spoken
at a
normal volume.