Acoustic properties of modified wood under different humid conditions and their relevance for musical instruments

Ahmed, Sheikh Ali; Αδαμόπουλος, Στέργιος

doi:10.1016/j.apacoust.2018.05.017

Cited by 37 publications

(31 citation statements)

References 28 publications

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“…At present, information on EMC dependence of vibrational properties of wood was identified within 26 references, ranging from the 1940s to recent years. As a general trend, it appears that the earlier references address both the between-species diversity and the multi-physical (moisture, temperature, frequency) dependence of vibrational behaviour (Fukada 1951;Greenhill 1942;James 1961;Kollmann and Krech 1960;Matsumoto 1962;Pentoney 1955;Sellevold et al 1975;Suzuki 1962Suzuki , 1980, while the later references tend to have a primary focus on how moisture content and vibrational properties are affected by wood modification (Ahmed and Adamopoulos 2018;Akitsu et al 1993;Kubojima et al 2000;Matsunaga et al 2000;Obataya et al 2000aObataya et al , 2001Sedighi Gilani et al 2014;Yano and Minato 1992;Yano et al 1986). This, of course, is only a general historical trend, and physical-mechanical behaviour and/or natural variability are still found as a main focus of studies on EMC-vibrational properties from the past 3 decades (Hunt 1997;Kubojima et al 2005a;Jiang et al 2012;Inokuchi et al 1999;Obataya and Norimoto 1995;Obataya et al 1998;Sasaki et al 1988;Viala 2018).…”

Section: Introductionmentioning

confidence: 99%

Moisture content dependence of anisotropic vibrational properties of wood at quasi equilibrium: analytical review and multi-trajectories experiments

Brémaud

Gril

2020

Holzforschung

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This article aims at providing a synthetic view of the equilibrium moisture content (EMC) dependence of wood vibrational properties (i.e. dynamic mechanical properties in the audio-frequency range), including specific dynamic modulus of elasticity (E′/γ) and damping coefficient expressing internal friction (tanδ). A series of multi-trajectories experiments was designed to complete an analytical review. Literature indicates that: (1) in longitudinal (L) direction, the EMC dependence of E′/γ shows a very consistent shape (rather linear) between studies, while its shape is non-linear for tanδ and varies significantly between studies; (2) EMC dependence of tanδ is rather well documented in the L direction, in adsorption, for softwoods, but data covering EMC dependence in both L and other anisotropic directions, and sorption hysteresis, are still scarce. Experiments were conducted on a softwood (spruce) and a hardwood (maple), in L and radial (R) directions, in full adsorption from oven-dry state, full desorption from water-saturated state, and relative humidity (RH) loops without extreme conditioning. Measurements were made at conditions considered “at equilibrium” and some were monitored through time. Results indicated that tanδ was much more (×3) sensitive to EMC differences than E′/γ. R properties, especially tanδR, were much more (×2–3) sensitive than L properties – resulting in strong increase of anisotropy with increasing EMC. In L direction, differences due to EMC remained moderate compared to the natural variability of wood for E′/γ, while for tanδ the EMC-induced changes were at least equal to natural variability in high-grade spruce. Vibrational properties did exhibit a hysteresis as a function of RH, but very little hysteresis as a function of EMC. The tanδ-EMC relation strongly depended on the actual time of stabilisation after reaching EMC. A related paper will address the transient, out of equilibrium effects of changing moisture conditions on the vibrational properties of wood.

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Section: Introductionmentioning

confidence: 99%

Moisture content dependence of anisotropic vibrational properties of wood at quasi equilibrium: analytical review and multi-trajectories experiments

Brémaud

Gril

2020

Holzforschung

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“…The velocity of sound in wood means that the speed at which wood transmits received energy. Wood with a high sound velocity and low internal damping, best facilitate the transmission of vibrational energy [8]. Therefore, sound velocity is an essential parameter to consider before recommending a material acoustically suitable, especially for making musical instrument.…”

Section: Speed Of Sound (C) and Sound Velocity (V)mentioning

confidence: 99%

Acoustic Properties of Musanga Cecrepoides Wood Samples Obtained from Different Stem Positions in Niger Delta Region of Nigeria

Aleru

Owoyemi

Olufemi

et al. 2021

OJC

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Musanga cecrepoides is an interesting wood species due to its diverse utility ranging from medicine, shade, ornaments etc. Research has been conducted on other properties of this wood species with little information about its acoustic properties. Thus, the evaluation of its acoustic properties is pertinent so as to increase the information bank of its properties. This study assessed the acoustic properties of Musanga cecrepoides wood obtained from selected states and locations in the Niger Delta region of Nigerian viz a vis, Rivers, Bayelsa and Delta States. Test samples were collected from different stem positions axially (top, middle, base) and radially (inner and outer) and analyzed using the statistical software package IBM SPSS Statistics, Version 23 (IBM Corporation, New York, USA). Analysis of variance (ANOVA) was performed at 5% level of significance to determine whether the assessed acoustic properties were significantly different among different stem positions. Results showed that sound frequency (f) at top wood (3061.71 Hz) and outer wood (3096.06 Hz) had significantly higher resonance frequency compared with the bottom wood (2768.01 Hz) and inner wood (2349.54 Hz) respectively. The mean sound velocity (v) at both the axial (2069.59 m/s) and radial (1905.96 m/s) stem positions fell short of the estimated mean v of other wood species when compared. However, such result is suitable for other acoustic purposes with moderate sound velocity. The sound radiation coefficient (R) values were highest at the bottom (4.18) axially and outer (4.13) radially when compared to other stem orientations of the wood. Whereas axially at the top (1561815.86 Kg/(m 2 s)) and radially at the outer position (1558292.53 Kg/(m 2 s) Sound Impedance (z) was highest when compared with other stem positions of the Musanga cecrepoides wood.

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“…This creates internal stresses due to the volume change, which influences the sound quality of the instrument and the sounding effect becomes unstable. Conversely, woods with better dimensional stability lead to a more stable overall sounding effect of the instrument [42].…”

Section: Physical and Mechanical Propertiesmentioning

confidence: 99%

Properties of common tropical hardwoods for fretboard of string instruments

et al. 2020

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Fretboards of string instruments are usually made of rare woods that commonly have a high density, strength, and hardness; further, they are wear resistant, uniform in texture, and feature an elegant color. To reduce the consumption of scarce timber resources, especially of endangered tropical hardwood species, suitable replacement materials should be identified. The substitute can be either common tree species having similar characteristics, or fast-growing plantation wood that has undergone modifications to match the performance of precious woods. This study compares the anatomical structure, physical features, mechanical properties, and surface color of three precious woods traditionally used in fretboards (ebony, Indian rosewood, and African blackwood) against maple, which is used for the backboard, ribs, and necks of string instruments. Based on the data, a set of performance evaluation indices for selecting alternative materials for fretboards is proposed. In specific, the replacement wood should be a diffuse-porous tropical hardwood with few vessels and a smaller diameter, thick fibrous walls, and a cell wall rate of more than 50%. In terms of physical properties, it should have low swelling coefficients for moisture and water absorption, and dimensional stability. The replacement should also display hardness values greater than 9.0 kN in the cross-section and greater than 6.0 kN in the tangential and radial sections. Further, it should have a high modulus of rupture (> 149 MPa) and elasticity (> 14.08 GPa), good impact bending strength, and good wear resistance (80-150 mg/100 r). To satisfy the traditional aesthetics, the wood surface color should be black, dark brown, or dark purple-brown, with colorimetric parameters in the range of 0.0 < L* < 30.0, 0.0 < b* < 6.0, and an a* value as small as possible. The evaluation indicators used for searching potential high-quality alternative tree species are not the same as those for replacing traditional fretboard materials using modified fast-growing plantation wood. The physical and mechanical properties and the surface color of traditional precious fretboard wood are important evaluation indicators for whether the modified fast-growing plantation wood can replace the traditional fretboard wood.

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Acoustic properties of modified wood under different humid conditions and their relevance for musical instruments

Cited by 37 publications

References 28 publications

Moisture content dependence of anisotropic vibrational properties of wood at quasi equilibrium: analytical review and multi-trajectories experiments

Moisture content dependence of anisotropic vibrational properties of wood at quasi equilibrium: analytical review and multi-trajectories experiments

Acoustic Properties of Musanga Cecrepoides Wood Samples Obtained from Different Stem Positions in Niger Delta Region of Nigeria

Properties of common tropical hardwoods for fretboard of string instruments

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