The $\textit{Mohm}$ is a unit of mechanical mobility for sound waves, being the reciprocal of the mechanical $ohm$ unit of impedance, i.e., for an acoustic medium, the ratio of the flux or volumic speed (area times particle speed) of the resulting waves through it to the effective sound pressure (i.e. force) causing them, the unit being qualified, according to the units used, as m.k.s. or c.g.s. The mechanical ohm is defined as: $$Mohm \equiv 1\,dyn\cdot\,s\cdot cm^{-1} \text{ or } 10^{-3} N\cdot s\cdot m^{-1}$$.
Mohm