COMPASS Hadron Spectroscopy -- Final states involving neutrals and kaons

The COMPASS experiment at CERN is well designed for light-hadron spectroscopy with emphasis on the detection of new states, in particular the search for $J^{PC}$-exotic states and glueballs. We have collected data with 190 GeV/c charged hadron beams on a liquid hydrogen and nuclear targets in 2008/09. The spectrometer features good coverage by electromagnetic calorimetry and a RICH detector further provides $\pi$ / $K$ separation, allowing for studying final states involving neutral particles like $\pi^0$ or $\eta$ as well as hidden strangeness, respectively. We discuss the status of ongoing analyses with specific focus on diffractively produced $(\pi^0\pi^0\pi)^{-}$ as well as $(K\bar{K}\pi)^{-}$ final states.