Acoustical simulation, design and experimental investigation of a classroom: A case study

Document Type : Research Article

Authors

1 BSc Student, Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran

2 Assistant Professor, Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran

Abstract

To improve teaching and learning conditions, room acoustics tries to adjust the educational environment. This research addresses the room acoustics of a small classroom in the Department of Mechanical Engineering at Isfahan University of Technology. It has been studied by modeling and simulating the classroom in the COMSOL software using the ray tracing method, and the reverberation time has been calculated. The model is validated by field measurements and using the impulse response function according to ISO 3382-2 in terms of the reverberation time. Then, it is compared with Eyring's and Sabin's empirical relationships, as well. The acoustics modes of the classroom have been obtained using the modal analysis in the COMSOL software. ANSI/ASA S12.60 is employed to design a suitable acoustical environment for the classroom and absorption panels and bass traps are utilized to reach the desired condition. After applying the adjustments, the reverberation time reached the recommended standard value, which increases the sound quality. Other acoustical parameters such as Definition (D_50), Clarity (C_50) and Sound Transmission Index (STI) have been calculated before and after the acoustic correction. Results revealed that speech intelligibility has fallen in the acceptable range.

Highlights

  • A classroom is modeled and simulated in the COMSOL software.
  • The numerical results from ray acoustics are compared with theoretical results.
  • Measured acoustical parameters are compared with numerical results.
  • The acoustics of the classroom is designed to improve the acoustical performance.
  • The final reverberation time is compared with the desired in ANSI/ASA S12.60

 

Keywords

Main Subjects

References

[1] A. Standard, ANSI/ASA S12. 60-2010/Part 1 American National Standard Acoustical Performance Criteria, Design Requirements, and Guidelines for Schools, Part 1: Permanent Schools, in:  USA: Acoustical Society of America, 2010.
[2] M. Hodgson, Rating, ranking, and understanding acoustical quality in university classrooms, Journal of the Acoustical Society of America, 112 (2002) 568-575.
[3] L. Nijs, M. Rychtáriková, Calculating the optimum reverberation time and absorption coefficient for good speech intelligibility in classroom design using U50, Acta Acustica united with Acustica, 97 (2011) 93-102.
[4] H. Kuttruff, Room acoustics, sixth edition, 2016.
[5] ASA, Classroom Acoustics 1: A resource for creating learning environments with desirable listening conditions, in, 2003.
[6] W. Yang, M. Hodgson, Acoustical evaluation of preschool classrooms, Noise Control Engineering Journal, 53 (2005) 43-52.
[7] A. Astolfi, V. Corrado, A. Griginis, Comparison between measured and calculated parameters for the acoustical characterization of small classrooms, Applied Acoustics, 69 (2008) 966-976.
[8] H.S. Awad, H.H. Farag, M.A. Hanafi, D.S. Taha, Architectural acoustics in educational facilities: An empirical study on University Classrooms in Egypt, in:  Proceedings of Meetings on Acoustics, 2012.
[9] BB93, Building Bulletin 93: acoustic design of schools - performance standards, in, 2003.
[10] R. Pääkkönen, T. Vehviläinen, J. Jokitulppo, O. Niemi, S. Nenonen, J. Vinha, Acoustics and new learning environment - A case study, Applied Acoustics, 100 (2015) 74-78.
[11] F. Fantozzi, M. Rocca, N. Spinelli, Assessment of reverberation times in university classroom: Comparison between analytic formulae, software simulations and measurements, in:  Building Simulation Conference Proceedings, 2019, pp. 10-17.
[12] ISO, ISO 3382-2:2008 Acoustics — Measurement of room acoustic parameters — Part 2: Reverberation time in ordinary rooms., in, 2008.
[13] D. Russo, A. Ruggiero, Choice of the optimal acoustic design of a school classroom and experimental verification, Applied Acoustics, 146 (2019) 280-287.
[14] A. Prodeus, M. Didkovska, Objective Assessment of Speech Intelligibility in Small and Medium-Sized Classrooms, in:  2020 IEEE International Conference on Problems of Infocommunications Science and Technology, PIC S and T 2020 - Proceedings, 2021, pp. 27-32.
[15] A.K. Abraham, M.S. Ravishankar, A case study of acoustic intervention in classrooms, Building Acoustics, 28 (2021) 293-308.
[16] COMSOL Multiphysics Acoustics Module User’s Guide, version 6.0 2021.
[17] M.D. Egan, Architectural Acoustics, J. Ross Pub., United Kingdom, 2007.
[18] R.F. Barron, Industrial noise control and acoustics, CRC Press, 2002.
[19] T.J. Cox, P. D’Antonio, Acoustic Absorbers and Diffusers, in, Spon Press,(2003 or 2004), 2009.
[20] I. Standard, ISO 9613-1:1993 Acoustics — Attenuation of sound during propagation outdoors — Part 1:, in:  Calculation of the absorption of sound by the atmosphere, 1993.
[21] M. Vorlaender, Auralization. Fundamentals of Acoustics, Modeling, Simulation, Algorithms and Acoustic Virtual Reality, 2008.
[22] ISO, Acoustics — Measurement of sound insulation in buildings and of building elements — Part 5: Field measurements of airborne sound insulation of façade elements and façades, in, 1998.
[23] M. Kleiner, J. Tichy, Acoustics of small rooms, 2014.
[24] IEC, IEC 60268-16: Sound system equipment—Part 16: Objective rating of speech intelligibility by speech transmission index, in, 2011.

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