Decibels: Level Noise Source Decibel Effect
- 150: Jet take-off (at 25 meters) Eardrum rupture
- 140: Aircraft carrier deck
- 130: Military jet aircraft take-off from aircraft carrier with afterburner at 50 ft (130 dB).
- 120: Thunderclap, chain saw. Oxygen torch (121 dB). Painful. 32 times as loud as 70 dB.
- 110: Steel mill, auto horn at 1 meter. Turbo-fan aircraft at takeoff power at 200 ft (118 dB). Riveting machine (110 dB); live rock music (108 – 114 dB). Average human pain threshold. 16 times as loud as 70 dB.
- 100: Jet take-off (at 305 meters), use of outboard motor, power lawn mower, motorcycle, farm tractor, jackhammer, garbage truck. Boeing 707 or DC-8 aircraft at one nautical mile (6080 ft) before landing (106 dB); jet flyover at 1000 feet (103 dB); Bell J-2A helicopter at 100 ft (100 dB). 8 times as loud as 70 dB. Serious damage possible in 8 hr exposure.
- 90: Boeing 737 or DC-9 aircraft at one nautical mile (6080 ft) before landing (97 dB); power mower (96 dB); motorcycle at 25 ft (90 dB). Newspaper press (97 dB). 4 times as loud as 70 dB. Likely damage in 8 hour exposure.
- 80: Garbage disposal, dishwasher, average factory, freight train (at 15 meters). Car wash at 20 ft (89 dB); propeller plane flyover at 1000 ft (88 dB); diesel truck 40 mph at 50 ft (84 dB); diesel train at 45 mph at 100 ft (83 dB). Food blender (88 dB); milling machine (85 dB); garbage disposal (80 dB). 2 times as loud as 70 dB. Possible damage in 8 hour exposure.
- 70: Passenger car at 65 mph at 25 ft (77 dB); freeway at 50 ft from pavement edge 10 a.m. (76 dB). Living room music (76 dB); radio or TV-audio, vacuum cleaner (70 dB). Arbitrary base of comparison. Upper 70s are annoyingly loud to some people.
- 60: Conversation in restaurant, office, background music, Air conditioning unit at 100 feet. Half as loud as 70 dB.
- 50: Conversation at home. Large electrical transformers at 100 feet. One-fourth as loud as 70 dB.
- 45: Davening murmur
- 40: Library; lowest limit of urban ambient sound One-eighth as loud as 70 dB.
- 30: Quiet rural area. One-sixteenth as loud as 70 dB. Very Quiet.
- 20: Whisper, rustling leaves
- 10: Breathing Barely audible
If what you are praying can be understood more than 10′ away, your tefilah is at home conversation levels and, by definition, distracting. If it’s distracting enough to be prohibited during Megillah reading on Purim, it’s distracting whether or not you feel it to be.
Your tefilah at 45 decibels is 100% halachically kosher. Tefilah that your neighbor hears is almost certainly questionable as too loud.
Rule of Thumb: Decide to be quieter than congregation’s Rav, Rosh Yeshiva, Rosh Kollel and Shaliach Tzibbur.