Noise Basics Flashcards
What is amplitude
- Loudness
- Variation in sound pressure
What is a decibel?
- A convenient way to compare sound pressure levels with different orders of magnitude
- Comparison made to the reference point
By how many decibels does sound pressure level decrease if you double the distance from the source?
6 db
What is the OSHA PEL for noise?
8-hour time-weighted average sound level (TWA) of 85 decibels measured on the A scale (slow response) or, equivalently, a dose of fifty percent.
What is the OSHA PEL exchange rate for noise?
5 dB
What is the OSHA PEL action level for noise?
8-hour time-weighted average sound level (TWA) of 85 decibels measured on the A scale (slow response) or, equivalently, a dose of fifty percent.
What types of noise are incorporated when monitoring for noise?
All continuous, intermittent and impulsive sound levels
What range of noise is integrated into noise measurements?
80 decibels to 130 decibels
What is the ACGIH TLV for noise?
8-hour time-weighted average sound level (TWA) of 85 decibels
What is the ACGIH exchange rate for noise?
3 dB
dBA frequency weighting is used most commonly…
In EHS. It weighs human frequencies more heavily
dBC frequency weighting is used most commonly…
for peak noise measurements. It heavily weights all but extremely high and low frequencies
What is dBZ most commonly used for?
Octave band analysis. It has a flat response (“unweighted”)
Why use frequency analysis?
- Ears have varying sensitivity based on frequency
- Useful in determining appropriate engineering controls
How are frequency categorized?
- Octave bands
- Octave band is range of frequencies where upper frequency is twice the lower frequency
How are octave bands generally described?
By their center frequency
What are engineering controls for noise control?
Absorption and sound barriers
What are types of absorption engineering controls?
- Porous: acoustic energy causes fibers to vibrate generating heat (good for high frequencies)
- Diaphragmatic: thin piece of material vibrates when hit by sound-absorbing energy (good for low frequencies)
- Resonant: pocket of air absorbs sound energy
What are examples of barrier engineering controls?
- Baffle: Barrier between source and person, good for high frequencies
- Partial enclosure: top on the baffle
- Complete enclosure: box around the person or the source
What are negative health outcomes that can result from noise exposure?
- Tinnitus
- Temporary threshold shift
- Standard threshold shift
- Higher frequency hearing is lost first
What frequencies are tested in audiometric testing?
- 500
- 1000
- 2000
- 3000
- 4000
What is a standard threshold shift?
- Exceed 10 dB drop in 2000, 3000, or 4000 in either ear
What is the noise reduction rating?
- The NRR is conducted in a laboratory
- Actual results will likely vary
- OSHA regulation 20 CFR 1910.95 Appendix B provides details on using the NRR
