The vibrational properties of multiphonon bound states in the region of the first and second overtone of orthorhombic HCl crystal have been studied by means of infrared spectroscopy. Triphonons have been observed and assigned on the bas is of the available theories of multiphonon crystal excitations. The Lorentzian widths of biphonon and triphonon bands have been determined from observed band profiles by band deconvolution as a function of temperature in the range 20-90 K. The temperature dependent bandwidths of biphonons and triphonons are compared and discussed in terms of depopulation and dephasing processes of the bound state.