Speech intelligibility is traditionally evaluated through tests that include speaker and listeners in a room. In the designing process, similar evaluations can be performed through a classical methodology, that takes the Reverberation Time and background noise into account, or through the assessment of speech-related parameters from the simulated Impulse Responses. The development of auralization techniques in the past decades has made it possible to perform listening tests in a virtual environment. However, simulated Impulse Responses of rooms usually do not include the background noise. This paper reports first steps towards a methodology for the evaluation of speech intelligibility in virtual classrooms, using auralized signals. Listening tests in an actual room are compared to tests performed with simulated Impulse Responses. Background noise of spectral content similar to the fan noise in the actual classroom were added to the test signals.2 11361143Mehta, M., Johnson, J., Rocafort, J., (1999) Architectural Acoustics: Principles and Design, , Columbus: Prentice Hall(2005) Sound System Equipment - Part 16: Objective Rating of Speech Intelligibility by Speech Transmission Index, , International Standard IEC 60268-16Bradley, J.S., Reich, R.D., Norcross, S.G., On the combined effects of signal-to-noise ratio and room acoustics on speech intelligibility (1999) J. Acoust. Soc. Am., 106 (4), pp. 1820-1828Kleiner, M., Dalenbäck, B.-I., Svensson, P., Auralization - An overview (1993) Jounal of the Audio Engineering Society, 41, pp. 861-875Hawley, M.L., Litovsky, R.Y., Colburn, H.S., Speech intelligibility and localization in a multi-source environment (1999) J. Acoust. Soc. Am., 105 (6), pp. 3436-3448Hawley, M.L., Litovsky, R.Y., The benefit of binaural hearing in a cocktail party: Effect of location and type of interferer (2004) J. Acoust. Soc. Am., 115 (2), pp. 833-843Helfer, K.S., Freyman, R.L., The role of visual speech cues in reducing energetic and informational masking (2005) J. Acoust. Soc. Am., 117 (2), pp. 842-849Allen, J.B., Berkley, D.A., Image method for efficiently simulating small-room acoustics (1979) J. Acoust. Soc. Am., 65 (4), pp. 943-950Vorlaender, M., International round robin on room acoustics computer simulations (1995) 15th International Congress on Acoustics, pp. 577-580. , Trondheim, NorwayTorres, R.R., Kleiner, M., Dalenbäck, B., Audibility of "Diffusion" in room acoustics auralization: An initial investigation (2000) ACUSTICA United with ACTA ACUSTICA, 86 (6), pp. 919-927