Sound

Sound Measurements

Sound is measured in decibels (db), much like temperature is measured in degrees and speed in miles (or kilometers) per hour. Like most other units, the bottom of the scale or 0 db, is an arbitrary setting, which by convention is set to be the level of the sound that we can bearly hear, or our hearing threshold, as it is normally known. One difference between the decibel scale and most of the other units we usually use in our everyday life, is the fact that the decibel scale is not linear, but logarithmic. In a linear scale, like velocity, if someone’s car is moving at 100 mph, we know that he is moving at twice the speed of someone else who is doing 50 mph, i.e. 2×50 mph is double the velocity of the second car. In logarithmic scales a sound which is only 3 db higher than another, has twice the energy. For example, if you look at the table below, the 9mm Para cartridge at 160 db has twice the sound energy of the .45 ACP cartridge which is measured at 157 db. Another complication is that the human ear does not hear linearly either. Although loudness is subjective, most people perceive one sound to be twice as loud as another, when there is a 10-fold increase in energy, or a difference of about 10 db. So a 60 db sound sounds twice as loud as a 50 db one, although there is 10 times more energy in it. Also, it is interesting to note that most people cann ot discern any difference in perceived loudness of less than 3 db. That means that the energy in the sound has to double, before someone can notice any difference. A typical wood-frame wall will stop between 30-45 decibels. Insulation and egg cartons don’t help. A second wall built just inside the first will add another 27-30 dB of sound protection. After this technical jargon, here is a table of loudness.

db	Environmental noise
-80	underwater nuclear submarine microphones listening to shrimp chewing on food at 100 meters distance
-30	one human talking 20 miles away ( 60 db / meter at a distance of 20 miles )
-4 to +4	the ticking of an ordinary wristwatch at 1 meter
0	beginning of hearing, a mosquito 10 feet away, the ear drum moves less than 1 / 100 the length of an air molecule
10	absolute silence, att-bell laboratory "quiet room", Normal breathing
13	ordinary light bulb hum
15	a pin drop from a hieght of 1 centimeter at a distance of 1 meter
20	Rusting leaves
30	totally quiet nightime in desert-impossible anywhere near city
30	Whisper at 30 feet
35	anechoic hearing test room 1998
40	a whisper, a normal conversation is 60 db, normal sound 70 db
40	Quiet street
50	Interior home noise
60	Conversation
70	Crowded restaurant
75	Kitchen appliances
80	City traffic
85	Hearing damage possible
85	beginning of hearing damage, earplugs should be worn
90	Lawn mower
100	Chain shaw
100	normal average car or house stereo at maximum volume
107	the beginning of pain at the most sensitive frequency of 2750 hertz
109	one sound watt radiating as a perfect sphere, 4 pi square meters 1986
110	a car stereo with two 6 x 9” speakers and 100 watts
114	a very large, powerful portable radio
116	human body begins to percieve vibration in the low frequencies
117	home stereo system, a very loud and powerful 200-2000 watts
120	front row at a rock concert- up to 200 refrigerator size speakers and 50000-300000 watts of clean, full frequency sound
120	Threshold of pain
120	Siren
125	drum set-only at the moment of striking, continous level 115
126	typical professional d.j. system
127	human tinnitus (ringing in the ears) begins
128	human, loudest scream measured at a distance of 8 feet 2 inches
128	human head hair begins to detect vibration
128	human can begin to detect very slow"blast wind” of 0.124 meters/second
134	.22 LR rifle
130	marching band-overall level at a distance, 100-200 members
132	eardrum"flex” totally noticeable
133	gunshot- ear level, may vary greatly to size and type of gun, duration converted to one second, peak level may reach 140-160
135	"very loud” car stereo, only bass level, highs rarely above 115
135	large train horn
135	human, a slight cooling effect begins to be noticed, from air expansion
137	human body vibration is strong
137	human ear all frequencies are painful
140	extremely damaging to hearing no matter how short the time exposure
140	blast wind = u = (particle velocity) is 0.49 meters per second or about 1 mph
140	human throat and vocal cord vibration begins
140	Jet engine at take-off
141	human body begins to feel nasuea after a few minutes
142	human body chestpounding is intence
142	inside a car with two pro 18 inch woofers and 300 watts each
143	human body feels as if someone just football tackled your chest
144	human nose itches
145	human vision begins to vibrate making it slightly blurry, 1-3 degrees
145	"competition” car stereo, sixteen 12 or eight 15, or four 18 speakers
147	formula 1 race car, 700 horsepower, chestpounding and suction force on calm quiet mornings can clearly be heard 6 miles away.
148	human vibration very uncomfortable and slightly painful
149	human lungs and breathing begins vibrating to the sound
150	rock concert"the who” two 10 story stacks = 144 double refridgerator sized speakers, actual level reached 120 db at a distance of 32 meters for this normalized reading of 150db.continous level 114-118db at 32 meters
150	rock concert speaker at 1600 watts on the actual vibrating surface
150	human sensation of being compressed as if underwater is overwhelming
150	human sound experiments down to 1 to 2 hertz – ref.13.
150	.410 shotgun
152	.22 LR pistol
152	human vibration is painul and also felt in all joints
153	20 gauge shotgun
153	human throat is vibrating so hard it is almost impossible to swallow
154	toy balloon popping, depends on type and how large and hard to inflate
155	human body compression and expansion to vibration is to the"core”
155	human cooling effect is high, as a guess 10 to 25 degrees farenheit?
155	.223 rifle
155	.25 pistol
156	12 gauge shotgun
156	.30-.30 rifle
156	.308 rifle
156	.44 Special revolver
156	in a mini-van with twenty 12” woofers and 19,000 watts of amplifier power. Each speakers is displacing (pumping back and forth ) 0.75 inches. If long hair women sit in it, her hair will fly out of window with bass. Windshield wipers fly off vehicle 1/2 to 2 inches, door and front Windshield flexion may be up to +-2 inches or 4 inches peak to peak. Even with earplugs (-30 db) and headmuffs (-24 db) = -54 db it’s still loud
157	.22 Magnum pistol
157	.45 ACP pistol
158	.380 ACP pistol
158	.38 Special revolver
158	human body vibration is violent, nausea becomes more intence
158	inside a rock concert speaker box refridgerator size at max. 5000 watts
159	.30-06
160	9mm Para pistol
160	flashlights exhibit electromagnetic pulsing-emp (dimming during sound)
162	u.s. festival rock concert 1983. 10 separate stacks, amps = 400,000 watts ,
163	.41 Magnum revolver
163	N.H.R.A. dragsters- 5000 to 7000 horsepower, liquid nitroglycerin fuel, Earthshaking at 50 feet, humans find it hard to see, and breathe 140db
163	glassbreaking level, minimum, it is very hard to break glass windows. Many stories come from breaking glass but it is highly variable: it is easier to break if the window already has a crack, is very large or old and brittle and not car safety glass which can flex massively. Before breaking. an opera singer at 110 db may break a wineglass but it is an example of frequency resonance, and not high sound db level
163	ocean whale reference 2 exp-5 newtons per square meter
164	internal sound pressure of a large jet airplane turbine motor
164	.44 Magnum revolver
165	the common type of fireworks at professional pyrotechnic shows
165	jet airplane, boeing 727-15,000 lbs of thrust, depends on the takeoff
165	motor driven piston headphones
166	air particle velocity is 10 meters per second or about 20 miles per hour
170	1 p.s.i. = 1 pound per square inch most sound readings Higher than this refer to p.s.i. instead of db. buildings and houses have approximately a 50 % chance of survival
171	worlds loudest car stereos, up to 80 speakers,32 car batterys, 100,000 watts, 125-138
171	acoustic air pressure generator
172	727, 737, 747, 757, 767 crusing at 6 miles high mach 0.84, at the ground (sea level) loses an additional 6 db because air dencity is only half sea level at a hieght of 6 miles
172	fog is created, depending on the temperature, dew point and humidity
173	bass injection tests, expierimental electromagnetic type speakers
173	= hydraulic, whole body dynamic pressure chamber, at 8 hertz
174	air begins to heat up due to compression, most shock waves are very hot
174	loudspeaker coupled manometer headphones down to 1 hertz
175	quarter dynamite stick, very close pressure may exceed 210 db
175.8	1 ton t.n.t. at 250 feet
177	= 2 p.s.i., damage to structures are significant, 30% survival
180	1 pound t.n.t. at 15 feet
180	= 3 p.s.i., damage to structures is catastrophic, when a shock wave hits a structure its momentum and pressure more than doubles, especially at higher db levels, dynamic wind is about 103 mile / hour and causes a large portion of damage, 15 % object survival
180	= motor drive coupled manometer static pressure, 165 db up to 50 hertz,
182	1 ton t.n.t at 150 feet, exactly 182.2 db
183	= 6 p.s.i. total destruction of all structures, particle velocity (Blast wind) is 180 miles per hour. 0.9 miles from hiroshima atomic bomb and 3.3 miles from 1megaton nuclear bomb, less 0.1 % object survival
185.75	0.375 pounds of t.n.t. riechter -1.5
186.1	1 pound t.n.t at distance of 10 feet
187	1 ton t.n.t. at 100 feet, exactly 186.8 db
190.60	riechter scale 0 (zero) earthquake
190.60	2.0000 pounds t.n.t.
191	bomb-very small 1 lb. or grenade, very close pressure may exceed 210 db
195	human eardrums rupture 50 % of time
195	1 ton t.n.t. at 60 feet
200.59	63.24 pounds of t.n.t., riechter scale 1
202	human death from sound (shock) wave alone. death from: schrapnel at any level above 165 db is likely and being thrown (10 feet per second) above 180 db
205	320 pounds of t.n.t. riechter 1.5
207	bomb, small sized 250 pounds, 14 foot wide crater, nearby may exceed 238 db
207.46	68.48 p.s.i.= (q), critical pressure, the shock wave pressure and dynamic (blast wind) pressure(q) are equal, louder than this dynamic pressure(q) will always be more than shock pressure. blast wind (particle velocity = u) is 1697 feet per second = 518 meters second = 1157 miles per hour. 400 feet from a 1000 ton t.n.t explosion
209	bomb, medium 500 pounds, 18 foot wide crater nearby may exceed 240 db .
210	N.A.S.A. 400,000 acoustic watts expierimental noisemaker 48 feet across of concrete and steel
210.6	earthquake reichter scale 2.0
210.6	1 ton of T.N.T. and a 23.40 foot crater
212	sonic boom average from jet
213	sonic boom generates approximately 1.2 gigawatts or 1.6 million horsepower
213	bomb 1 ton tnt, 23 foot wide crater or 175.8 db at 250 feet. 213.44 exact .4.
214.09	10 atmospheres, db(q) blast wind = 217.439 db(q)
215	space shuttle launch exhaust, approximately 3 miles per second
215	thunder, the largest positive giants. ordinary thunder 165-180 db.lightning strike on ocean surface 234db at 2exp-5 newtons per square meter
215	battleship new jersey firing all 9 sixteen inch guns
216	inside a normal car engine cylinder with a 9 to 1 compression ratio
218.2	sonic boom f-16. at 100 feet high = 3.92 lbs.per square foot = 139.6db, +78.6db = 8536.5 meters high . 2002
220	Bomb, largest used in wwii, wieghing 11 tons and 25 feet long . 2001
220	saturn 5 rocketship, melts concrete and burns grass one mile away. Reached a velocity of 5 miles per second and moon on july 20, 1969
220	space shuttle landing sonic boom with velocity of mach 20 1998
225	inside a normal diesel motor semi-truck cylinder 25 to 1 compression
226.59	train explosion 2004 feb 19 09:37am neyshabur, iran, runaway train, possible terrorism, shattered windows at 15 km.,crater is 500 feet diameter and 50 feet deep, magnitude 3.6 riechter, at several miles “the entire area shook”, heard at 75 km, equal to 251.195 tons of t.n.t., 51 car train = 17 cars sulpher, 6 cars gasoline, 7 cars ammonium nitrate fertilizer (a.n.f.o.), 10 cars cotton wool, 3 left at station not involved, 8 miscellaneous loads
228.1	exactly. 1 pound of t.n.t. at a distance of 1 foot
229	seafloor volcanic eruption, reference 2 exp-5 newtons per square meter
230.59	earthquake riechter 4.0
230.59	1000 tons of t.n.t.
232	large non-nuclear explosion, 500 tons, 1917 destruction of german WWI tunnels in messines ridge belgium, heard or felt in london
235	1 ton t.n.t. at 10 feet,
235.3 db	tornado average, 5100 tons of t.n.t. 2004
235.19	earthquake riechter 5.0
235.19	31624 tons of t.n.t.
240	one kiloton of t.n.t explosive, 233 foot wide crater 29 feet deep,10 p.s.i. at 1000 feet , 230 db at 10000 ft
240	tornado, fujitsu 5, energy guess based on 300 mile per hour wind, 1 mile wide
243	largest non-nuclear explosion ever, 1947 destruction of nazi u-boat pens used 7100 tons of explosive
247	bomb inside shock wave maximum limit pressure of t.n.t. explosive
248	atomic bomb-hiroshima and nagasaki japan aug. 6, 9, 1945.tragically killed 300,000 peaple. totally disintegrated 16 square miles, cracked distant concrete walls 12” thick, equal to 20,000 tons of t.n.t., wind was around 300 miles per hour, destroyed walls 28” thick at 1 mile.power to make a crater 633 feet wide and 80 feet deep
255	600 kilotons ground burst crater is 2112 feet wide and 211 feet deep
257	nuclear bomb, 1 megaton (1 million tons of t.n.t.) nuclear bomb “oak” 8.9 megaton, enewetak,june 29 1958,5740 feet wide 204 deep crater
261	= dynamic blast wind pressure generated from a 1000 atmosphere overpressure
274	= 10000 atmospheres overpressure, dynamic pressure = 282.042 db
278	nuclear bomb,"bravo” test 15 megatons, 1954, bikini atoll, marshall islands
282	nuclear bomb, 57 megatons hydrogen largest ever detonated, 1961 shock waves circled the earth 3 times, first orbit took 36 hr 27 min.
286	mt. saint helens volcano eruption-baby volcano, blew down trees 16 miles away. could be seen from outer space on the space shuttle. Blew out some windows in seattle-tacoma 200 miles away, 163 db
296	earthquake 8.6 riechter scale- ground moved up and down 13 feet. . 1988
300	hurricane – average, extreme energy is"diluted” by covering 500,00o square miles. energy = approx. 1000 nuclear bombs a second.
302	tungusta siberia meteor, blew down houses 600 miles away . 1989
310	krakatoa volcano eruption-1883 a.d., cracked one foot thick concrete. At 300 miles, created a 3000 foot tidal wave, heard 3100 miles away,sound pressure caused barometers to fluctuate wildly at 100 miles indicating levels of at least 170-190 db at this distance of 100 miles even when shouting in someones ear, could not be heard at 100 miles. Caused fog to appear and disappear instantly at hundreds of miles. Rocks were thrown to a hieght of 34 miles. dust and debris fell continously for 10 days after blast. produced very colorful sunsets for one year, ejected 4 cubic miles of the earth. created anti-node of negative pressure at the exact opposite side of the earth.sound covered 1 / 10 of the worlds surface, shock (sound) waves"echoed” around the earth 36 times and lasted for about a month!
316	volcano eruption sorantini, italy,1470 b.c. although more energy than krakatoa, it blew up over a longer period of days and not as violently, hence the instant peak pressure is believed to be lower than krakatoa. 15 cubic miles ejected, created tidal wave 165 feet high at a distance of 80 miles.
320	volcano eruption, tambora indonesia,1815, ejected 36 cubic miles.approximately equal to 14,000 megaton nuclear bombs or a 14 gigaton bomb based on ejected volume,change in megatons times 1.345 equals volume ejected change.if was a nuclear bomb it would create a crater about 12.4 miles wide and 1.33 miles deep.internal pressure is believed to be about 47 million p.s.i. = 347 db .