NRR means Noise Reduction Ratio and 30 db (decibels) is about average. 30db hearing protection would be commonly used by shooters to reduce the sound of gun fire.
30
There are several types of dB. dB SPL are decibels measuring sound pressure levels. There is an accepted reference point of 0 dB SPL which equals 20 micropascals = 2 × 10-5 pascals. dB SL are decibels measuring a signal relative to an individuals auditory threshold. For example, if a person's minimum threshold is 30 dB HL (yet another type of decibel measuring how much worse a person's hearing is based on a referential dB level) and a signal is at 40 dB HL, the sensation level of this signal to this individual is 10 db SL (40 dB - 30 dB = 10 dB SL).
40 dB has ten times the power of 30 dB. 50 dB has another ten times as much power.
dB mean Decibel.
dB (decibel) is a logarithmic measure of the ratio of two power values, for example, two signal strengths. This is often used for power gain or power loss. For example, a loss of 10 dB means that the signal degrades by a factor of 10, a loss of 20 dB means that the signal degrades by a factor of 100, and a loss of 30 dB means that the signal degrades by a factor of 1000.
The answer is 22.
What does DB 3 925 CN mean
112
dB is the abbreviation of Decibel
what does DB stand for on grades
24;
"Permitted Exposure Time Guidelines - SPL"Sound pressure level Lp and permissible exposure time t:115 dB = 0.46875 minutes (~30 sec)112 dB = 0.9375 minutes (~1 min)109 dB = 1.875 minutes (< 2 min)106 dB = 3.75 minutes (< 4 min)103 dB = 7.5 minutes100 dB = 15 minutes97 dB = 30 minutes94 dB = 1 hour91 dB = 2 hours88 dB = 4 hours85 dB = 8 hours82 dB = 16 hoursLower dBs are said to be harmless