• W. H. Tan Mechanical Engineering Programme, Faculty of Mechanical Engineering & Technology, Universiti Malaysia Perlis (UniMAP), 02600 Arau, Perlis, Malaysia.
  • N. Muhammad Hafiz Mechanical Engineering Programme, Faculty of Mechanical Engineering & Technology, Universiti Malaysia Perlis (UniMAP), 02600 Arau, Perlis, Malaysia.
  • C. K. Chan Mechanical Engineering Department, Faculty of Engineering and Quantity Surveying, INTI International University, Persiaran Perdana BBN, Putra Nilai, 71800 Nilai, Negeri Sembilan, Malaysia.
  • J. Niresh Department of Automobile Engineering, PSG College of Technology, India.



Acoustics, Speech Intelligibility, Reverberation Time, Sound-absorbing Material, Lecture Room


Acoustic analysis is a measurement used to analyse the behaviour of sound waves in enclosed spaces, which influences speech intelligibility. Another parameter that influences speech intelligibility is reverberation time. Reverberation time is the time for the sound source to decay by 60 dB. A high reverberation time causes sound to dissipate more slowly, resulting in continual reflection of sound waves, which disrupts student concentration in class. Furthermore, a poor acoustic environment could have an impact on health and lecture delivery. The objective of this study is to determine and analyse the acoustic performance for five selected lecture rooms in UniMAP. The reverberation time is the parameter of this study that was obtained from the Root Mean Square (RMS) of the sound pressure by using the impulsive sound source method from a burst balloon. In this study, the "balloon pop" sound pressure was consistently recorded at approximately 105dB across all cases. This measurement indicates the peak sound intensity of the stimulus. The influence of the location of receiver, design, and space volume for the lecture room on the reverberation time was investigated. At a location of 6 m from the sound source, at the back wall of a room with chairs, BKN 5 and BPU 5 measured longer reverberation times of 1.3 s and 1.2 s, respectively. The higher value of reverberation time is caused by where the sound receiver is. If it is close to a wall, the sound receiver will be exposed to numerous reflections of sound waves, causing the room to become reverberant. Compared to other lecture rooms, the length of BKN 5 and BPU 5 is shorter. Their lengths are 11.639 m and 11.689 m, so the sound receiver is closer to the wall and makes the reverberation time higher. BKN 5 room, which has a volume of 258.3 m3, had the highest reverberation time (1.2 s on average in a room with chairs). This is because it is larger than the other rooms. So, the reverberation times get longer as the room's volume increases. BPU 5 room had the longest reverberation time for a condition room without chairs (an average of 2.4 s), but it also had the smallest space volume (242.4 m3) compared to the other rooms. Thus, it takes longer for the sound waves in the room to fade away when there are no chairs there. If the smaller room didn't have enough sound-absorbing materials, the reverberation times would be longer.


M. Hodgson, 1999. “Experimental investigation of the acoustical characteristics of university classrooms,” Journal of the Acoustical Society of America 106(4): 1810–1819. DOI:

Y. J. Choi, 2020. “The intelligibility of speech in university classrooms during lectures,” Applied Acoustics 162: 107211, DOI:

P. N. Reinhart and P. E. Souza, 2016. “Intelligibility and clarity of reverberant speech: Effects of wide dynamic range compression release time and working memory,” Journal of Speech, Language, and Hearing Research, 59(6): 1543–1554. DOI:

W. Yang and J. S. Bradley, 2009. “Effects of room acoustics on the intelligibility of speech in classrooms for young children,” Journal of the Acoustical Society of America. 125(2): 922–933. DOI:

M. Meissner, 2017. “Acoustics of small rectangular rooms: Analytical and numerical determination of reverberation parameters,” Applied Acoustics 120: 111–119, DOI:

W. Yang and M. Hodgson, 2006. “Auralization study of optimum reverberation times for speech intelligibility for normal and hearing-impaired listeners in classrooms with diffuse sound fields,” Journal of the Acoustical Society of America. 120(2): 801–807, DOI:

A. Gramez and F. Boubenider, 2017. “Acoustic comfort evaluation for a conference room: A case study,” Applied Acoustics. 118: 39–49,


A. Nowoświat and M. Olechowska, 2017 “Estimation of Reverberation Time in Classrooms Using the Residual Minimization Method,” Archives of Acoustics. 42(4): 609–617. DOI:

J. S. Bradley, 2002. “Acoustical Design of Rooms for Speech,” Construction Technology Update. 51: 1–6,

E. Odoh and N. Urenyang, 2012. “Preliminary Quantification of the Acoustic Properties of Some Selected Lecture Theatres in Federal University of Technology, Yola – Nigeria,” FUTY Journal of the Environment. 7(1): 34–50, DOI:

R. S.youssef, D. Bard, A. E. F. A. Mahmoud, and N. M. Esa, 2014. “Acoustical quality assessment of lecture halls at Lund University, Sweden,” INTERNOISE 2014 - 43rd International Congress Noise Control Eng. Improv. World Through Noise Control, 1–10,

J. O. M. Amasuomo and J. E.-E. Ntibi, 2017. “An analysis of acoustical effectiveness in the design of lecture hall spaces for teaching-learning: The case of Niger Delta,” International Journal of Development and Sustainability, 6(12):2127–2144,

V. Gómez Escobar and J. M. Barrigón Morillas, 2015. “Analysis of intelligibility and reverberation time recommendations in educational rooms,” Applied Acoustics. 96:1–10, DOI:

C. R. Kunchur, 2019. “Evaluating Room Acoustics for Speech Intelligibility,” Open Journal of Applied Sciences, 9(7):pp. 601–612, DOI:

Y. Daheng and L. Qi, 2012. “Research of Computer Simulation of Reverberation Time in Classroom,” Physics Procedia, 33:1677–1682, DOI:

K. Jambrosic, M. Horvat, and H. Domitrovic, 2008. “Reverberation time measuring methods,” Proceedings of the European Conference Noise Control, 2014: 4503–4508, DOI:

NtiAudio, 2021. “Reverberation Time.” acoustics/reverberation-time (accessed Nov. 17, 2021).

L. Davis, 2021. “Reverberation Time in Room Acoustics,” (accessed Nov. 16, 2021).

D. Cotoros, R. Cotoros, and A. Stanciu, 2018. “Analysis of acoustic response and treatment of a rehabilitated lecture room,” Springer Proceedings in Physics 198: 113–119, DOI:

C. Nestoras and S. Dance, 2013. “The interrelationship between room acoustics parameters as measured in university classrooms using four source configurations,” Building Acoustics, 20(1): 43–54, DOI:







How to Cite