diplomski projekt
Bogdan Mitkovski (Author), Željko Gorišek (Reviewer), Aleš Straže (Mentor)

Abstract

Raziskali smo vpliv strukture lesa na akustične lastnosti pri lesenih tolkalih. Vizualno smo izbrali les afriškega padouka, robinije in javorja ter izdelali preizkušance manjših dimenzij. S slušnim preverjanjem smo preizkušance najprej razvrstili v 5 kakovostnih razredov, nato pa pri impulzno elastičnem mehanskem vzbujanju izmerili lastno frekvenco in dušenje zvoka ter določili kazalnike akustične kakovosti. Vizualna ocena kakovosti lesa za lesena tolkala se je dobro ujemala z meritvami hitrosti zvoka vzdolţ lesnih vlaken ter prečnega specifičnega elastičnega modula. Pri lesu afriškega padouka so potek in orientacija lesnih vlaken ter teksturne posebnosti pomembno vplivale na akustično kakovost preizkušancev; gostota lesa pa neznačilno. Primerljivo instrumentalno in slušno razvrščanje preizkušancev padouka smo dosegli s koeficientom dušenja zvoka (tan ) ter z relativno učinkovitostjo akustične pretvorbe (RACE). Pri podobnem povprečnem specifičnem elastičnem modulu (E / ) lesa javorja, robinije in padouka smo potrdili bistveno večje dušenje zvoka pri domačih lesnih vrstah.

Keywords

les;lesena tolkala;akustične lastnosti;struktura lesa;

Data

Language: Slovenian
Year of publishing:
Typology: 2.11 - Undergraduate Thesis
Organization: UL BF - Biotechnical Faculty
Publisher: [B. Mitkovski]
UDC: 630*812.12
COBISS: 2167689 Link will open in a new window
Views: 418
Downloads: 89
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Other data

Secondary language: English
Secondary title: Structural and acoustical properties of wood for percussion instruments
Secondary abstract: We investigated the influence of the structure of wood on acoustic properties. We have visually selected planks of African padouk, black locust and maple woods and cut test specimens of smaller dimensions. We have graded the wood specimens into 5 acoustic quality grades by hearing examination and later measured the fundamental frequency and sound damping with elastic mechanical excitation and determined selected acoustic quality indicators. Visual assessment of raw wood quality matched closely to the measurements of the speed of sound along the grain and to the transverse specific modulus of elasticity. Grain angle and texture strongly affected the acoustic quality of African padouk, while density did not have a significant impact. We have reached similar grading between hearing examination and instrumental measurements of test specimens using damping coefficient (tan ) and relative acoustic conversion efficiency (RACE). While having similar average values of specific modulus of elasticity (E / ), African padouk returned lower damping coefficient than black locust or maple.
Secondary keywords: wood;wooden percussion instruments;acoustic properties;wood structure;
Type (COBISS): Diploma project paper
Thesis comment: Univ. v Ljubljani, Biotehniška fak., Oddelek za lesarstvo
Pages: IX, 35 f.
ID: 11904362