Dr Siu-Kit Lau and Prof Shiu-Keung Tang have chaired a session of Classroom Acoustics at the 171st Meeting of Acoustical Society of America in Salt Lake City on 23-27 May 2016. During the meeting, Prof Tang and Dr Lau presented a paper entitled “Cantonese speech intelligibility tests in two Hong Kong primary school classrooms”. Abstract of the presentation can be found at this link. A preliminary observation is that there is higher probability for the pupils to give wrong answers when the sound of a character lasts for relatively long duration, especially when there are abrupt temporal changes in the time-frequency spectra. Correct answers are usually given when the corresponding time-frequency spectral energy is more concentrated within a short duration.