Hasil Pencarian  ::  Simpan CSV :: Kembali

Abstrak :
The utilization of bricks made of styrofoam is expectedly able to be a soundproof for noise control and as a preventive action to reduce the steadily increasing prevalence of hearing loss. This study aimed to assess the use of sound absorption material in which styrofoam was utilized to reduce the noise exposure. In this study, fine aggregates (sand and styrofoam) were made with a mixture of cement with a composition of 1:4 and 1:6, also the addition of polystyrene waste with a percentage of 0%, 20%, 40%, 60%, and 80%. Determination of acoustical property of the mixture was done by testing the sound absorption coefficient using Four Microphones Impedance Tube (ISO 140-3). The results showed that the highest value of absorption coefficient was at a frequency of 800 Hz with an additional 80% styrofoam for the composition of 1:4 at 0.4100 dB and at a frequency of 800 Hz with an additional 40% styrofoam for the composition of 1:6 at 0.5870 dB.

Abstrak :
Informasi sifat akustik untuk kayu tropis Indonesia masih sangat terbatas. Penelitian ini bertujuan untuk menguji beberapa sifat akustik dari jenis kayu Sonokeling (Dalbergia latifolia), Mahoni (Swietenia mahagony), Akasia (Acacia mangium) dan Manii (Maesopsiseminii). Paramater sifat akustik yang diuji terdiri dari kapasitas damping berupa logarithmic decrement, penyerapan suara, dan kecepatan gelombang suara; selain itu diuji pula kerapatan dan sifat kekakuan atau modulus elatisitas kayu. Pengujian dilakukan pada contoh uji dari 3 pola kayu gergajian yaitu radial, tangensial, dan campuran (quarter-sawn,flat-sawn, and plain-sawn) dengan menggunakan metode vibrasi longitudinal dan waktu tempuh rambatan gelombang suara ultraonik untuk pengujian sifat akustik. Hasil penelitian menunjukkan tidak ada pengaruh yang nyata dari pola penggergajian terhadap nilai sifat akustik kayu. Berdasarkan sifat akustik yang diuji maka jenis kayu Mahoni dan Sonokeling memiliki sifat akustik logarithmic decrement yang rendah, kecepatan gelombang suara ultrasonik yang tinggi, dan rasio kekakuan bahan terhadap kerapatannya yang besar; sehingga jenis kayu tersebut direkomendasikan baik untuk komponen alat musik. Sementara itu, jenis kayu Akasia dan Manni lebih cocok digunakan sebagai komponen akustika bangunan, kaitannya dengan sifat penyerapan bunyinya yang lebih baik.

---

Abstract
The acoustical properties of four Indonesian tropical hardwood species were evaluated in this study. The objectives of this study were to determine acoustical parameters e.g. l ogarithmic decrement, sound absorption, sound velocity as well as density and wood stiffness; and to evaluate the potential of those species for acoustical purposes. Sonokeling (Dalbergia latifolia), Mahoni (Swietenia mahagony), Acacia (Acacia mangium) and Manii wood (Maesopsis eminii) were selected in this research. Three different cutting plane patterns of sawn tim ber (quarter-sawn, flat-sawn, and plain-sawn) were converted into small specimens. The methods for determining acoustical properties were longitudinal vibration testing and time of flight of ultrasonic wave method. The result showed no significant difference (α=0.05) of acoustical properties in logarithmic decrement, sound absorption, and ultrasonic velocity means on quarter-sawn, flat-sawn, and plain-sawn for all wood species tested. We found that Mahoni and Sonokeling had good acoustical properties of logarithmic decrement, ultrasonic wave velocity, and ratio of wood stiffness to wood density; and is preferred for crafting musical instruments. Acacia and Manii woods are recommended for developing acoustic panels in building construction because those species possess higher sound absorption values.