Noise Flashcards
What is noise?
Undesirable or unwanted sound
Subjective
What is noise propagation?
Generated at a source and spreads spherically away from that source
Diminished with distance and loses engery
What occurs as “sounds waves” when objects are encountered?
Bending and diffraction
How is sound measured logarithmically?
bel (B)
What is the more commonly used subunit for sound?
Decibel (dB)
1/10 bel
The power of a sound wave is proportional to the…..
Square of the pressure
Combinations of sounds may make ____ in the decibels.
Little
At what level would a person receive painless damage?
85-125 dB
At what level would a person start to feel pain?
Over 125 dB
Frequency
Vibrating object moves molecules back and forth causing sound waves to move outward
What is the range of normal hearing?
20 Hz to 20 kHz
Steady frequencies
Pure tones
Tuning forks and electronic oscillators Uncommon
Intensity
Directly proportional to sound pressure
Pascals (Pa) and micropascals (uPa)
What is the normal range for intensity?
20 uPa to 20 Pa
What is the A scale?
Sound measurement as an approximation of the sensitivity of the human ear
2 sounds with the pressure lvl may have different A levels