dB is Logrithmic
... Most manufacturers use +-3db and it seems to be 'the industry standard' (I saw it written exactly this way within the last week) that this is the minimum change in volume most people can detect while listening to their chosen speaker system.
There is reasonable ancedotal evidence that at least those with a trained ear can detect differences as low as 1db when listening to music (see audioholics U).
So, what is an acceptable on axis response? +-3db, +-2db, +-1db, less than +-1db? ....Fred
You do realize that dB measurement is a logrithmic measurement and that 3 dB is a doubling of volume. you also need to understand where your baseline is. If you start with a baseline of 35db Aneholic test room is different from 85dB beginning of hering damge is different from 120-130 dB front row of rock concert.
An increase of 1 dB is a 25.89 % increase over current dB level
An increase of 2 dB is a 58.49 % increase over current dB level
An increase of 3 dB is a 100.00 % ( actually 99.526231%) over current dB Level
-80?(P) UNDERWATER NUCLEAR SUBMARINE MICROPHONES LISTENING TO SHRIMP CHEWING ON FOOD AT 100 METERS DISTANCE
-30 (N) ONE HUMAN TALKING 20 MILES AWAY ( 60 DB / METER AT A DISTANCE OF 20 MILES )-REF.1.2003
-4 TO +4 (N) THE TICKING OF AN ORDINARY WRISTWATCH AT 1 METER -REF.1 2003
0 (N) BEGINNING OF HEARING, A MOSQUITO 10 FEET AWAY, THE EAR DRUM MOVES LESS -REF.1.1990
THAN 1 / 100 THE LENGTH OF AN AIR MOLECULE (N)
3.5 (P) 1E-10 METERS OF MERCURY = 0.0000000001 METERS OF MERCURY
10 (P) ABSOLUTE SILENCE, ATT-BELL LABORATORY “ QUIET ROOM “
13 (P) ORDINARY LIGHT BULB HUM
15 (N) A PIN DROP FROM A HIEGHT OF 1 CENTIMETER AT A DISTANCE OF 1 METER -REF.1.2003
30 (P) TOTALLY QUIET NIGHTIME IN DESERT-IMPOSSIBLE ANYWHERE NEAR CITY
35 (P) ANECHOIC HEARING TEST ROOM -REF.1. 1998
40 A WHISPER, A NORMAL CONVERSATION IS 60 DB, NORMAL SOUND 70 DB -REF.1.1983
73.98(P) = 1 uBAR = 1 microbar pressure
85 BEGINNING OF HEARING DAMAGE, EARPLUGS SHOULD BE WORN
93.98(P) = 1 PASCAL PRESSURE
100 NORMAL AVERAGE CAR OR HOUSE STEREO AT MAXIMUM VOLUME -REF.1.1982
107-104 (P) THE BEGINNING OF PAIN AT THE MOST SENSITIVE FREQUENCY OF 2750 HERTZ -REF.1.1982
109 ONE SOUND WATT RADIATING AS A PERFECT SPHERE, 4 PI SQUARE METERS -REF.1. 1986
110 A CAR STEREO WITH TWO 6 X 9” SPEAKERS AND 100 WATTS -REF.1.1982
114-107 A VERY LARGE, POWERFUL PORTABLE RADIO REF.1.1982
116 HUMAN BODY BEGINS TO PERCIEVE VIBRATION IN THE LOW FREQUENCIES -REF.1.1986
117-123 HOME STEREO SYSTEM, A VERY LOUD AND POWERFUL 200-2000 WATTS -REF.1.1983120.24(P) ONE PURE SOUND WATT FLOWING THROUGH 1 SQUARE METER, YOUR ELECTRIC AMPLIFIER MAY BE 3000 WATTS.ALSO A TESTIMONY TO HEARING SENSITIVITY -REF.1.1986
120-130 FRONT ROW AT A ROCK CONCERT- UP TO 200 REFRIGERATOR SIZE SPEAKERS
125 DRUM SET-ONLY AT THE MOMENT OF STRIKING, CONTINOUS LEVEL 115
126-130 TYPICAL PROFESSIONAL D.J. SYSTEM -REF.1.1984
127 HUMAN TINNITUS (RINGING IN THE EARS) BEGINS -REF.1.1984
127.
128 (P)HUMAN, LOUDEST SCREAM MEASURED AT A DISTANCE OF 8 FEET 2 INCHES
128
132.4(P) = 1 SOUND WATT MAXIMUM IN A SMALL SEALED BOX BELOW HYDRODYNAMIC CRITICAL LOW FREQUENCY
133 (N)GUNSHOT- EAR LEVEL, MAY VARY GREATLY TO SIZE AND TYPE OF GUN,
DURATION CONVERTED TO ONE SECOND, PEAK LEVEL MAY REACH 140-160
135-122 (P) “VERY LOUD” CAR STEREO, ONLY BASS LEVEL, HIGHS RARELY ABOVE 115(P) -REF.1.1983
135-130(N) LARGE TRAIN HORN -REF.1.1985
145-136 (P)“COMPETITION” CAR STEREO, SIXTEEN 12 OR EIGHT 15, OR FOUR 18 SPEAKERS -REF.1.1983
150 (N)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 150 DB.CONTINOUS LEVEL 114-118db (P) AT 32 METERS -REF.1.1982
150 ROCK CONCERT SPEAKER AT 1600 WATTS ON THE ACTUAL VIBRATING SURFACE -REF.1.1991
153 HUMAN THROAT IS VIBRATING SO HARD IT IS ALMOST IMPOSSIBLE TO SWALLOW -REF.1.1983
154 TOY BALLOON POPPING, DEPENDS ON TYPE AND HOW LARGE AND HARD TO INFLATE -REF.1.1986
155 HUMAN BODY COMPRESSION AND EXPANSION TO VIBRATION IS TO THE “CORE” -REF.1.1983
158 HUMAN BODY VIBRATION IS VIOLENT, NAUSEA BECOMES MORE INTENCE -REF.1.1983
158 (P)INSIDE A ROCK CONCERT SPEAKER BOX REFRIDGERATOR SIZE AT MAX. 5000 WATTS -REF.1.1983
160 (P)FLASHLIGHTS EXHIBIT ELECTROMAGNETIC PULSING-EMP (DIMMING DURING SOUND) -REF.1.1983
162 U.S. FESTIVAL ROCK CONCERT 1983. 10 SEPARATE STACKS, AMPS = 400,000 WATTS (N) -REF.1.1983,-REF.3.
183 (P) = 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 % 209 (N)BOMB, MEDIUM 500 POUNDS, 18 FOOT WIDE CRATER NEARBY MAY EXCEED 240 db (P) -REF.2.4.
210 N.A.S.A. 400,000 ACOUSTIC WATTS EXPIERIMENTAL NOISEMAKER 48 FEET ACROSS OF CONCRETE AND STEEL
220 (N)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 ?(N)SPACE SHUTTLE LANDING SONIC BOOM WITH VELOCITY OF MACH 20 -REF.1. 1998
225 (P) INSIDE A NORMAL DIESEL MOTOR SEMI-TRUCK CYLINDER 25 TO 1 COMPRESSION
248 (N)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 -REF.1.2.
300 (N)HURRICANE – AVERAGE, EXTREME ENERGY IS “DILUTED” BY COVERING 500,000
320 (N)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 (P) -REF.1.3.
