{'fraction_non_alphanumeric': 0.01476510067114094, 'fraction_numerical': 0.0013422818791946308, 'mean_word_length': 5.264705882352941, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Acoustics vs. psychoacoustics: An objective and subjective analysis of classroom acoustics in Singapore

Studies on the impact of psychoacoustics on noise annoyance especially for classroom environment were scarce. This article presents the results of a series of investigations on several classrooms on a university campus. Few objective measurement results such as sound pressure level, loudness and sharpness are obtained. The questionnaires are used to determine the noise annoyance of different types of the classroom, computer laboratory and discussion room in the school building. The results show that the acoustic performances of most classrooms do not meet the guidelines of the International Standards of 35 dB(A). In addition, the level of noise caused by air-conditioning and surrounding classroom has shown to increase the noise annoyance of the students that may affect the students' learning. Seven sound pressure level (SPL) models are compared and analyzed with the measured values. The comparison of different models shows that the SPL prediction is quite a frequency dependent and the model proposed by the Heerema and Hodgson shows better results at the mid-range frequency while the Sabine produced a good match at the high and low-frequency range. The proposed regression models from measurements between the equivalent sound pressure level and loudness can be used to estimate the noise annoyance level of the classroom during the building design and planning stage.