That's an in vitro study, in isolated cells, which used a totally non-physiological dose of lidocaine.
It's not even a mouse or rat study. It's less valuable than that.
Lidocaine, taken systemically, is associated with serious side effects. It's the only known "cure" for tinnitus, but its side effect profile is so nasty that pretty much nobody uses it.
Don't give irresponsible advice.