author =   {Eric A. Lehmann and Anders M. Johansson},
  title =    {Prediction of energy decay in room impulse responses simulated with an image-source model},
  journal =  {Journal of the Acoustical Society of America},
  volume =   {124},
  number =   {1},
  pages =    {269--277},
  month =    {July},
  year =     {2008},
  abstract = {A method is proposed that provides an approximation of the acoustic energy decay (energy--time curve) in room impulse responses generated using the image-source technique. A geometrical analysis of the image-source principle leads to a closed-form expression describing the energy decay curve, with the resulting formula being valid for a uniform as well as non-uniform definition of the enclosure's six absorption coefficients. The accuracy of the proposed approximation is demonstrated on the basis of impulse-response simulations involving various room sizes and reverberation levels, with uniform and non-uniform sound absorption coefficients. An application example for the proposed method is illustrated by considering the task of predicting an enclosure's reflection coefficients in order to achieve a specific reverberation level. The technique presented in this work enables designers to undertake a preliminary analysis of a simulated reverberant environment without the need for time-consuming image-method simulations.}