This paper is a preliminary report on acoustical studies of the sugar-cane fiber-board, emphasis being made for cases in which the fiberboard was perforated.Experiments with the non-perforated fiberboard indicated the existence of "mechanical vibration" determined by its boundary conditions including peripheral constraint, as well as of resonance absorption of thin panels backed by an air-space. When the fiberboard was perforated, resonance peaks became less prominent but the over-all absorption was higher than ordinary perforated panel absorbers previously investigated. In addition, two new types of perforated sound absorbers were briefly discussed.For most cases theoretical interpretations were given, especially on the basis of specific acoustic resistance, and both advantages and disadvantages for these fiberboard sound absorbers were discussed in the conclusion.