Experimental results on sound absorption coefficients of Malaysian woods

Janatul Islah Mohammad, Norhasnira Johari, Md Radzai Said, Mohd. Jailani Mohd Nor

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Sound absorption coefficient is an important parameter to calculate the reverberation time of an enclosure. There are published data inside text books on the sound absorption coefficients of typical materials, such as concrete, carpet, drapes, etc. However, the sound absorption coefficients of Malaysian wood have not been published to date. These woods are divided into four different categories, which are heavy hardwoods, medium hardwoods, light hardwoods and softwoods. This paper presents preliminary results of the sound absorption coefficients of two types of Malaysian woods: Balau (Shorea spp) and Nyatoh (Species of Sapotaceae); based on the transfer function method using the impedance tube. A bigger tube (100 mm) is used for measuring the sound absorption coefficients at lower frequencies (below 800 Hz) and a smaller tube (28 mm) is used for measuring the sound absorption coefficients at higher frequencies (above 800 Hz). It is found that the sample with the highest sound absorption coefficient is 18 mm Balau (higher density) while the lowest is the 34 mm Nyatoh (lower density) without the presence of air gaps. With variation of air gaps present, Nyatoh shows the more substantial results in comparison with Balau whereby the absorption coefficient are significantly higher than the ones without air gaps. However, the overall absorption coefficient remains low (below 0.2) at all frequencies, regardless having different thickness, density and variation of air gaps of up to 3".

Original languageEnglish
Title of host publication40th International Congress and Exposition on Noise Control Engineering 2011, INTER-NOISE 2011
Pages2940-2946
Number of pages7
Volume4
Publication statusPublished - 2011
Event40th International Congress and Exposition on Noise Control Engineering 2011, INTER-NOISE 2011 - Osaka
Duration: 4 Sep 20117 Sep 2011

Other

Other40th International Congress and Exposition on Noise Control Engineering 2011, INTER-NOISE 2011
CityOsaka
Period4/9/117/9/11

Fingerprint

sound transmission
absorptivity
air
tubes
reverberation
enclosure
transfer functions
impedance
low frequencies

Keywords

  • Absorption coefficient
  • Impedance tube
  • Malaysian woods

ASJC Scopus subject areas

  • Acoustics and Ultrasonics

Cite this

Mohammad, J. I., Johari, N., Said, M. R., & Mohd Nor, M. J. (2011). Experimental results on sound absorption coefficients of Malaysian woods. In 40th International Congress and Exposition on Noise Control Engineering 2011, INTER-NOISE 2011 (Vol. 4, pp. 2940-2946)

Experimental results on sound absorption coefficients of Malaysian woods. / Mohammad, Janatul Islah; Johari, Norhasnira; Said, Md Radzai; Mohd Nor, Mohd. Jailani.

40th International Congress and Exposition on Noise Control Engineering 2011, INTER-NOISE 2011. Vol. 4 2011. p. 2940-2946.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Mohammad, JI, Johari, N, Said, MR & Mohd Nor, MJ 2011, Experimental results on sound absorption coefficients of Malaysian woods. in 40th International Congress and Exposition on Noise Control Engineering 2011, INTER-NOISE 2011. vol. 4, pp. 2940-2946, 40th International Congress and Exposition on Noise Control Engineering 2011, INTER-NOISE 2011, Osaka, 4/9/11.
Mohammad JI, Johari N, Said MR, Mohd Nor MJ. Experimental results on sound absorption coefficients of Malaysian woods. In 40th International Congress and Exposition on Noise Control Engineering 2011, INTER-NOISE 2011. Vol. 4. 2011. p. 2940-2946
Mohammad, Janatul Islah ; Johari, Norhasnira ; Said, Md Radzai ; Mohd Nor, Mohd. Jailani. / Experimental results on sound absorption coefficients of Malaysian woods. 40th International Congress and Exposition on Noise Control Engineering 2011, INTER-NOISE 2011. Vol. 4 2011. pp. 2940-2946
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