ACOUSTIC AND ELECTRICAL PROPERTIES OF WOOD Flashcards
- is in relation to sound or it
refers to its capacity to absorb
or reflect sound and reduce
vibrations
Acoustic Property
- ability to absorb and prevent
reflections of sound
Acoustic Property
- has a high damping capacity; therefore, it is an ideal material for structural components in which vibration is unwanted
Acoustic Property
WOOD IS ACOUSTIC:
- Presence of pores, vessel lines, and microcapillaries
- Fabricated holes
- Fabricated striations
_________ wood is effective as a sound-absorbing material because it exhibits a small specific impedance (Smardzewski et al. (2014)
high porosity
__________ is essential in the design and construction of musical
instruments, The placement, size, and shape of these holes
influence the resonance, tone, volume, and overall acoustic
performance of the instrument
fabricated holes
__________ is a craftsmanship of the instrument, including how the wood is treated, shaped, and assembled, also plays a significant
role in determining the final sound.
fabricated striations
SOFTWOOD has a _____ sound absorption at high frequencies;
effective in reducing echoes and
_____ sound reflection;
better for diffusing sound.
high; moderate
HARDWOOD has a ____ sound absorption overall; absorbs less high-frequency sound and ____ sound reflection especially at lower frequencies.
lower; high
_______ are better in reflecting soundwaves
softwoods
_______ are sustain and creates more sharp tone
hardwood
______ are less sustain and has a softer tones
softwood
- Unit used to measure sound, named after Alexander Graham
Bell
DECIBEL
______ decibel is the normal level for human.
60-70
_____ is the maximum for safe volume level for ears.
80 dB
_____ for breathing and _____ for whisper
10 dB; 15 dB
- Capacity of wood to withstand induced vibration by sound waves transmitted from the outside forces
RESONANCE OF WOOD
- Deals with the movement or flow of energy in the form of electric charge such as electrons.
ELECTRICAL PROPERTIES OF WOOD
Movement of electricity can be classified in two different ways:
- Direct Current (DC) and
- Alternating Current (AC)
- flow of electric charge in one direction.
Direct Current (DC)
- flow of electric charge that frequently reverses direction.
Alternating Current (AC)
DIRECT CURRENT (DC) ELECTRICAL
PROPERTIES OF WOOD:
a. Resistivity
b. Conductivity
- exhibits how strongly it resists the flow of electric current.
Resistivity
- as the MC of wood increases from ovendry to FSP, resistivity decreases.
Resistivity
- as the MC continue to increase from FSP to complete MC saturation in wood, the
smaller its electrical resistivity (Glass,et al., 2010)
Resistivity
high MOISTURE CONTENT, low RESISTIVITY (vice versa)
low MOISTURE CONTENT, high RESISTIVITY
– reciprocal of electrical resistivity.
Conductivity
- wood’s ability to conduct electric current.
Conductivity
- electrical conductivity of wood increases as temperature increases unlike the conductivity of metal.
Conductivity
- the wood conductivity is greater along the grain direction compared to the direction across the grain,
and greater in the radial section than in the tangential section (Glass, et.al., 2010).
Conductivity
The AC electrical properties of wood deals with the _____
constant.
dielectric
- also known as relative permittivity
Dielectric Constant
- is defined as the ratio of the permittivity of a substance to the permittivity of free space
Dielectric Constant
The dielectric constant of wood is basically the __________________ stored in wood in the form of electric polarization when the material is in a given electric field
measure of energy per unit volume
FACTORS AFFECTING ELECTRICAL
PROPERTIES OF WOOD:
- Moisture Content
- Temperature
- Wood Type
- Grain Orientation
