Possible Pressure Waves of Supersolid Helium at High Pressure
  We make comments on Kim and Chan's [{\it Phys. Rev. Lett.} 97, 115302 (2006)] letter. Based on their pressure-dependent measurements (by a torsional oscillator technique), we propose that the {\it supersolid} fraction ($\rho_s/\rho$) might be relevant to an sound absorption or attenuation (fluctuations of pressure waves) in microscopic domain since there is no apparent change in $T_c$ with pressure. 
Kwang-Hua W. Chu