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Browsing by Subject "Acoustics"

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  • Järveläinen, Niilo (2021)
    Objectives. This study compares the acoustic effects of wood-based materials commonly used in speaker construction in a closed enclosure structure. The purpose of the study was to determine the effects of different enclosure materials on speaker acoustics and how these properties of different materials affect the sound reproduction of the loudspeaker. Previous studies indicate that the speaker enclosure material may have measurable effects on the acoustics of certain types of speakers, for example, due to the vibration and damping properties of the material. Methods. In this study the properties of speaker enclosures made of three different materials with identical structure were measured, and based on the measurements, conclusions were drawn about the effects the materials had on the acoustic properties of the loudspeaker. A closed enclosure structure was selected for this study to best show the material’s own properties in the measurements. MDF board, plywood and pinewood were selected as the test materials. The measurements were performed with calibrated measuring equipment in the same environment. The same speaker element was used for all necessary measurements. Results. The materials each affected the acoustics of the speaker differently. MDF and plywood had properties close to each other in terms of both frequency response and sound decay time, as measured by a microphone, but according to the decay measurements made with an accelerometer and an oscilloscope, the sound decay time of plywood was clearly the shortest. Pinewood had the longest sound decay time in microphone measurements, as well as in decay measurements performed with an accelerometer. According to the measurement results, it can be interpreted that the sound produced by the loudspeaker was least affected by plywood. The MDF board affected the sound produced by the speaker element more than the plywood, but pinewood had the greatest effect on the sound reproduction of the speaker. The effect of material on sound was most pronounced in the decay measurements with respect to sound damping time. The longer the sound damping time, the slower the material absorbs the energy applied to it and the longer the sound rings in the material, interfering with the speaker sound.