What is the real SPL db of an Earthquake vs sensurround?

[JBL4645]

My apologies if the text is all clustered together I cant figure out, why?

I thought Id keep this one separate from the yesterdays earthquake that stuck Japan that subject is different matter.

For years Ive had this, fascination about earthquakes. Ive experienced Universals 1974 disaster flick EARTHQUAKE that was exhibited in several types of Sensurround I think the one in the uk was 70mm six-track mag with those huge Cerwin-Vega stacked somewhere behind the screen at the local ABC Bournemouth screen 1.

It was monster of sound system and to tell the truth I wasnt into cinema sound systems back then, but I could remember looking to left and right sides as parts of the eerier sounds of river dam sliding away near the last half the film. The Big One was nuts when it kicked in! I thought the ceiling would give way it was LOUD!

Loud enough to tempt me to come back a few days later and a few more times some 4 times at 79pence a cinema ticket for BIG SOUND! I was unaware that it might cause mild tinnitus which I noticed some years later around 1978. I was 8 when I saw EARTHQUAKE and if I knew of the sound pressure risks I would have used earplugs!!

So, I have mild tinnitus. I can still hear up to about 16KHz but the tone is very distant small narrow wavelength the rest of the tones below it get louder as their easier to hear.

Anyhow point of thread what is the REAL SPL db of an EARTHQUAKE I find it hard to believe 120db! Sure the ground moves side to side and forwards and backwards swaying around and around till it STOPS! Im sure its an unpleasant experience!

I doubt many would care to get an SPL db metre out when an EARTHQUAKE strikes for a few seconds? Its not one would do, (rather than get the hell of out of the house straight-away)!

I know sound can pass though walls, shhh these walls have ears! Weve all heard that expression and yes its true some walls depending on how their made will transmit some sound though at given SPL db level and frequency varies, you might hear a muffed voices in the somewhere 500Hz to 2KHz or less when placing the ear against the wall.

I dont think real EARTHQUAKES make 120db it was needed for cinema to get the sound pressure of frequencies pounding in audiences faces! But it has risks of hearing damage! So what if the cinema wants to cause a bit of structural damage that can be fixed! Tinnitus however cant be fixed!

Last time I played EARTHQUAKE on DVD was a few years go chapter 8 and had the level up to 120dbc it was unpleasant to say the least! Unpleasant because I can since/feel that muffled like sound on the ear afterwards, its done no different I hope to what Ive been hearing ON and OFF over the years, but again it was unpleasant!!

I just dont think a real quake will output in open air outside away from buildings 120dbc! I think its less and its the motion that one would feel.

[garyrc]

Let's put the victims of the Japan quake in our prayers, and send financial support, if possible.

As to the sound issues:

I think the main energy of a real earthquake reaches down to a much lower frequency than SenseAround with it's Cerwin Vegas and huge horns can produce. It is literally felt rather than being heard. My guess is what you hear in a real earthquake is mostly the buildings and the upper layers of the earth flexing in response to the movement of the fault or movement in the subduction zone.

As to SPL, I was in the quake of '89 in San Francisco, and what I heard, rather than felt, was probably 15Hz to maybe as high as 30 Hz at about 90 to 115 dB or so, agumented by the expanded metal in the walls shrieking like the violin glisandi in Psycho. At first the sound was like a railroad train coming from a long way off, then bearing down on me. I started to hear it just slightly before I felt it. As I moved to take cover, the first big pulse came, and threw me against the wall, after which the floor rolled like ocean waves. The sound now was bassier than the oncoming train sound.

Our 7.2 quake lasted only about 15 seconds, and seemed like forever. Some buildings and one freeway did collapse. The Japan 8.9 quake lasted several minutes .... I cannot imagine ...

[JBL4645]

Let's put the victims of the Japan quake in our prayers, and send financial support, if possible.

As to the sound issues:

I think the main energy of a real earthquake reaches down to a much lower frequency than SenseAround with it's Cerwin Vegas and huge horns can produce. It is literally felt rather than being heard. My guess is what you hear in a real earthquake is mostly the buildings and the upper layers of the earth flexing in response to the movement of the fault or movement in the subduction zone.

As to SPL, I was in the quake of '89 in San Francisco, and what I heard, rather than felt, was probably 15Hz to maybe as high as 30 Hz at about 90 to 115 dB or so, agumented by the expanded metal in the walls shrieking like the violin glisandi in Psycho. At first the sound was like a railroad train coming from a long way off, then bearing down on me. I started to hear it just slightly before I felt it. As I moved to take cover, the first big pulse came, and threw me against the wall, after which the floor rolled like ocean waves. The sound now was bassier than the oncoming train sound.

Our 7.2 quake lasted only about 15 seconds, and seemed like forever. Some buildings and one freeway did collapse. The Japan 8.9 quake lasted several minutes .... I cannot imagine ...

Im not heartless I feel for the victims and yet find the whole earthquake issue interesting and strangely I play earthquake on DVD.

I remember the 1989 earthquake in news. The picture of the freeway was used on back cover Earthquake on re-issue widescreen laserdisc.

I think youre post puts it into proper content good memory for recall I guess it stuck in your memory firmly. Its like me shaking a filing cabinet its going to sound loud!

But on the outside say in field I know you, werent anywhere near to field as it would sound different.

I think sub should be fixed into walls to create a mild level not high get too carried away until something breaks!

I think the room above the basement should be used and the basement to house 18 subs stacked in the room with few inches for the port to breath and use the whole floor and then stack the same cluster on top of the ones stacked on the floor with matching amps to each sub and crossover and PEQ for each sub and master PEQ for the single LFE.1 output.

I think that would do it! At softer level with WTF scare the wits out of you. Peter Fonda! The drunk Earthquake

As for stacking subs in huge clusters it might rattle the floorboards something silly!

Im surprised the film still gets 70mm screenings at special SenSurround cinema house in England and Germany. But 4 screenings for me left its mark me. I prefer a lesser level today at home and there are those (shakers) so subs need only to be at lesser level which means less hearing loss issues. Films arent that realistic otherwise it would level the cinema in less than 1min.

I wonder what they used to balance the sound system for sensurround? I know Dolby employed EQ into the CP processors to get better response from the loudspeakers so what did sensurround use back in 1974 and slightly onwards till it was retired.

[Mallette]

I suspect the SPL of an earthquake is very dependent upon the strata and distance. I also attended the sensasurround version of Earthquake back in the day an I must say it was very convincing. Can't recall precisely, but I believe it was in the single digits, 8hz or so. At those levels it may well have been in excess of a 120db as you don't hear it anyway. Fact is I was in Texas, watching a movie called "Earthquake," fully aware of sensurround, and yet the bone shaking that ensured made me want to get under something as my brain said "this is REALLY happening!" Very uncanny and disconcerting.

Dave

[JBL4645]

I suspect the SPL of an earthquake is very dependent upon the strata and distance. I also attended the sensasurround version of Earthquake back in the day an I must say it was very convincing. Can't recall precisely, but I believe it was in the single digits, 8hz or so. At those levels it may well have been in excess of a 120db as you don't hear it anyway. Fact is I was in Texas, watching a movie called "Earthquake," fully aware of sensurround, and yet the bone shaking that ensured made me want to get under something as my brain said "this is REALLY happening!" Very uncanny and disconcerting.

Dave

For a moment I thought you was going say look for cover underneath the cinema seat LOL The DVD only goes as far as 20Hz its mostly peaking between 30Hz to 40Hz and 50Hz then shallows downwards. Ive PEQ it so I can stretch it down to 15Hz with flat response where it starts swallowing off. Maybe Universal band limited the LFE.1 as they dont want a lawsuit issue with home owners suing because it damaged the home? LOL

What was the ticket price at the cinema if you can recall that?

[djk]

The CV speakers were maybe 10dB down at 16hz, depends on the size of the stack and the loading in the room.

They did not play loud enough to cause hearing damage (unless you walked up and stuck your head in the mouth while they were playing).

OSHA allows for exposure up to 140dB for short durations below 100hz. The 15 minute OSHA limit is 115dBA, the one hour limit is 105dBA.

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"OSHA 'A' scale readings roll-off the bass at a 6dB/oct rate below 1Khz. So a 105dBA exposure for one hour could hit 130dB at 40hz and be OK. Too damn loud, you bet. Damaging levels, not according to OSHA. It's usually the excessive treble that gets crowd complaints (the bass gets the neighbors complaining).

Car stereo with its 150+ dB peak levels is another issue. I will not get in a car that can play louder than about 130dB, even if I am wearing full coverage ear protection, bone conduction will get you."

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I played in a 17-piece horn band in my younger days. Later, I got tinnitus from Amoxicillin (Medications categorized as being ototoxic are those which can adversely
affect the cochlea or vestibular structures in the ear. Antibiotics are
among the classifications of drugs that can produce side effects such as
dizziness, vertigo, tinnitus or hearing loss. One or more of these side
effects may occur.)

[Mallette]

The DVD only goes as far as 20Hz its mostly peaking between 30Hz to 40Hz and 50Hz then shallows downwards.

Not surprising. The sensarround stuff wasn't on the soundtrack but completely separate equipment that was triggered at the right times. I wouldn't be surprised if it no longer exists.

Dave

[garyrc]

Shaking the floor:

• My Klipschorns could shake the (firm, wood) floor pretty good even before I added a sub. They did so in one passage from Mahler's 9th, with the tympani, bass drum, and tam-tam in Fanfare for the Common Man, the DVD of Around the World in 80 days (1956 version) when the rocket took off in the prologue (originally in 70 mm and six channel magnetic), and the DVD of Ben-Hur, during the thunderstorm and suggested earthquake (also originally 6 track mag 70)
• The above films also shook the (concrete) floor of the Coronet theater during their 70 mm presentations. The theater system ( 5 custom and gargantuan JBLs behind the screen and JBL surrounds, as assembled by Ampex for Todd-AO, for which the theater was equipped in 1955), although very powerful, was spected to roll off somewhere below 40 Hz, although I read that when working in unison, they went lower.
• All of the above were almost as impressive as SenseAround, but in a different way. IMO, they were just as dramatic, probably with as high a SPL. They all could create a wind that you can feel on your face, and they all flapped my pants legs. But they lacked the very low bass down to what I now vaguely remember, thanks to someone mentioning it above, was advertised in a magazine (High Fidelity? Stereo Review?) as reaching 8 Hz.
• None of the IMAX theaters I have been in (3) can hold a candle to any of the above. The IMAX system just deosn't seem to move enough air in the bass to smack you in the face the way the others did. Could that be because the IMAX speaker enclosures don't have the very large bass reinforcing baffles around them?

[JBL4645]

The CV speakers were maybe 10dB down at 16hz, depends on the size of the stack and the loading in the room.

They did not play loud enough to cause hearing damage (unless you walked up and stuck your head in the mouth while they were playing).

OSHA allows for exposure up to 140dB for short durations below 100hz. The 15 minute OSHA limit is 115dBA, the one hour limit is 105dBA.

--------------------------------------------------------------------------------------------------

"OSHA 'A' scale readings roll-off the bass at a 6dB/oct rate below 1Khz. So a 105dBA exposure for one hour could hit 130dB at 40hz and be OK. Too *** loud, you bet. Damaging levels, not according to OSHA. It's usually the excessive treble that gets crowd complaints (the bass gets the neighbors complaining).

Car stereo with its 150+ dB peak levels is another issue. I will not get in a car that can play louder than about 130dB, even if I am wearing full coverage ear protection, bone conduction will get you."

-------------------------------------------------------------------------------------------------------

I played in a 17-piece horn band in my younger days. Later, I got tinnitus from Amoxicillin (Medications categorized as being ototoxic are those which can adversely

affect the cochlea or vestibular structures in the ear. Antibiotics are

among the classifications of drugs that can produce side effects such as

dizziness, vertigo, tinnitus or hearing loss. One or more of these side

effects may occur.)

Yet the duration of the earthquake The Gig One only lasted for about 9min in the cinema Id have to time the laserdisc ntsc version over the region2 DVD which is about 8 1/2 mins.Youd be crackers to stuck youre head in the mouth kinder like sticking youre head in lions mouth at the circus! LOL What do you think those CV go for today I guess not many of them around that turn up on ebay. I've only seen one on Lansing Heritage forums. I guess a few here have one or two CV from the sensurround days.

[JBL4645]

The DVD only goes as far as 20Hz its mostly peaking between 30Hz to 40Hz and 50Hz then shallows downwards.

Not surprising. The sensarround stuff wasn't on the soundtrack but completely separate equipment that was triggered at the right times. I wouldn't be surprised if it no longer exists.

Dave

Many no doubt have read Dolby labs in San Francisco has one of the sensurround sound generator models, yes it was trigged as I leaned over the years by pulse signal on the film. A diy model was made here in England several years go to replicate the sensurround experience in Bradford early 2000s I think 2004? I guess they loan the model out for some cinemas playing earthquake I dont know?

It would be nice if Universal provided the same cinema-like Universal opening with original logo as the region2 is spoilt with that updated Universal opening with music and its loud and it sets the tone all wrong, I have to mute it every time then de-mute at the right moment when the John Williams score starts. Also the warning would be bonus it would tickle me to read it again, it sets the tone up for the film!

Sensurround will be 40 years old in 2014 and I think Universal should do a sensurround box-set with bonus extras for each film not an hour I mean several hours of extras that have been published and new extras found in the vaults.

Also audio commentaries/ original sensurround soundtrack for varies versions for 35mm and 70mm and new re-mix or the version that was created for the DVD is okay except extended the frequency response down lower to what it was let us worry about LP filters etc keep it original because people are suckers for originals!

[Guest " "]

nuclear blast = 250db, Volcano eruptions = 272 dB, Blue whales = 188 decibels, Rocket Launching= 180, Jet Engine = 140, Thunderclap = 130, Jet takeoff (200 ft) = 120 , earthquake = ?

[JBL4645]

Shaking the floor:

• My Klipschorns could shake the (firm, wood) floor pretty good even before I added a sub. They did so in one passage from Mahler's 9th, with the tympani, bass drum, and tam-tam in Fanfare for the Common Man, the DVD of Around the World in 80 days (1956 version) when the rocket took off in the prologue (originally in 70 mm and six channel magnetic), and the DVD of Ben-Hur, during the thunderstorm and suggested earthquake (also originally 6 track mag 70)
• The above films also shook the (concrete) floor of the Coronet theater during their 70 mm presentations. The theater system ( 5 custom and gargantuan JBLs behind the screen and JBL surrounds, as assembled by Ampex for Todd-AO, for which the theater was equipped in 1955), although very powerful, was spected to roll off somewhere below 40 Hz, although I read that when working in unison, they went lower.
• All of the above were almost as impressive as SenseAround, but in a different way. IMO, they were just as dramatic, probably with as high a SPL. They all could create a wind that you can feel on your face, and they all flapped my pants legs. But they lacked the very low bass down to what I now vaguely remember, thanks to someone mentioning it above, was advertised in a magazine (High Fidelity? Stereo Review?) as reaching 8 Hz.
• None of the IMAX theaters I have been in (3) can hold a candle to any of the above. The IMAX system just deosn't seem to move enough air in the bass to smack you in the face the way the others did. Could that be because the IMAX speaker enclosures don't have the very large bass reinforcing baffles around them?

The Common Man is mostly horn with the odd boom, boom tympani. They did a pop version in the 70s for the Olympics. It was in the UK chats for several weeks! I like both versions.

Odd that IMAX doesnt quit do that the local IMAX in my town now closed and forgotten was loud at times with 120dbc on the meter for Haunted Castle but something was missing in the lows elusive? It was good compared to local commercial cinemas only 200 yards away from the IMAX that couldnt or couldnt be asked to make films better experience. It was just bass that I can hear and mildly feel in I place my arms on the seat beside me, or placing my, foot on one of the dodgy wooden floorboards that vibrated at certain SPL frequencies. The IMAX was all concrete carpeted of coarse LOL

Ive managed to make my concrete floor vibrate like it jumped up by a few millimetres with the torpedo explosion on the oil tanker doors was blasted on The spy who loved me DVD LFE.1. Mind you it was loud and bit unnecessary. The neighbours must be thinking WWIII is happening overhead!

The amp level was mostly used up for that and I dare do it again.

I played the earthquake week before last with just the LFE.1 running TURNED IT UP! It was unpleasant it sounds like the raw THX bass peak management on most AVR when you set the subs to peak level! The rumbling was rattling the letterbox! Opened the door and walked outside the tone dips up and down it sounded louder just outside the door. If I walked a few steps further out it dips down and peaks up. I was merely experimenting with an idea.

SPL db was around 110dbc in the living room I dared play it 120dbc luck not many people was in at the time below me during the afternoon.

[JBL4645]

nuclear blast = 250db, Volcano eruptions = 272 dB, Blue whales = 188 decibels, Rocket Launching= 180, Jet Engine = 140, Thunderclap = 130, Jet takeoff (200 ft) = 120 , earthquake = ?

WHOA! 250dbc I can believe that! I read somewhere years ago that THX cinema can recreate an atomic blaster, ether that or someone was having me on. LOL It would kill the audience! The shock to the system! I have few films on DVD with atomic fabricated kabooms! I dont think its possible to do it in the home without wiping out the whole town! [] well maybe just the neighbourhood.

So maybe its fact 120dbc for an earthquake! Thunderstorms I seem to recall using the SPL db metre outside many years ago on thunder and lighting storm and not once did the level go over 110dbc much less 100db it was within the 90dbc range and yes it was low and loud rumbles across the region. Maybe it wasnt the loudest thunderstorm recoded?

[Mallette]

I think Universal should do a sensurround box-set with bonus extras for each film not an hour I mean several hours of extras that have been published and new extras found in the vaults.

Well, I really don't know how many of us there are, but certainly plenty that like you and I would purchase a BR with the original freq program intact even if the movie sucked. No one mentioned, perhaps because few would want to admit it, but Battlestar Galactica (which was every bit as inspid as the TV program) was also release in sensarround. REALLY emphasized how much warp engines roar in the vacuum of space. []

Nonetheless, we audiophools would buy it under the "Dukes" mantra: "If it SOUNDS good, it IS good!"

Dave

[JBL4645]

I think Universal should do a sensurround box-set with bonus extras for each film not an hour I mean several hours of extras that have been published and new extras found in the vaults.

Well, I really don't know how many of us there are, but certainly plenty that like you and I would purchase a BR with the original freq program intact even if the movie sucked. No one mentioned, perhaps because few would want to admit it, but Battlestar Galactica (which was every bit as inspid as the TV program) was also release in sensarround. REALLY emphasized how much warp engines roar in the vacuum of space.

Nonetheless, we audiophools would buy it under the "Dukes" mantra: "If it SOUNDS good, it IS good!"

Dave

I was watching space 1999 on bluray recently and the lows to high pitched sounds of eagles LOL. I saw Battlestar Galactica in sensurround same cinema when it opened and remember the deep roar of the fighters blaster roar along the cinema and out into space blasting cylons into atoms of cosmic dust! That was the last film I saw in sensurround not sure if Rollercoaster or Midway played in town I guess Rollercoaster would be certificate AA so no one under the age of 15 or 16 to be admitted. I guess Midway would be rated A like Battlestatr and Earthquake.

Battlestar tv show came out a few years later wasnt it early 80s. Im surprised they didnt mix the new show in with Dolby digital mega sound sensurround THX LOL

[Mallette]

tv show came out a few years later wasn’t it early 80’s.

1978. The "movie" was just some of the TV stuff strung together. The recent series was pretty decent, though it wandered a lot before getting to the point.

Dave

[garyrc]

“The Common Man” is mostly horn with the odd boom, boom tympani. They did a pop version in the 70’s for the Olympics. It was in the UK chats for several weeks!

The best version of "Common Man" I have heard is on Crystal Clear records' "Sonic Spectacular." While it has the brass you mention, the tympani, bass drum and tam-tam are overwhelming! There is a desk in the path of my speakers (quite a ways away) and the power of the tympani & bass drum throw it temporarly out of square. This may illustate the point that measured SPL isn't everything .... another version of "Man," on Reference Recordings can be adjusted to have equal SPL as read by a meter ("c" "fast"), but doesn't have near the force, wind, or emotional impact. I think this is because the Crystal Clear version had better micing on the percussion, and the recording had more content in, perhaps, the 40 to 80 Hz range.

[michael hurd]

nuclear blast = 250db, Volcano eruptions = 272 dB, Blue whales = 188 decibels, Rocket Launching= 180, Jet Engine = 140, Thunderclap = 130, Jet takeoff (200 ft) = 120 , earthquake = ?

From what I have read, the theoretical limit is 194 db in air?

[JBL4645]

tv show came out a few years later wasnt it early 80s.

1978. The "movie" was just some of the TV stuff strung together. The recent series was pretty decent, though it wandered a lot before getting to the point.

Dave

Huh, you must have better memory of the show when it stated then I do. I might have seen a few episodes on TV. I think it used to be Saturdays, sometime around 5pm? I might have been interested in the CB radio my then you, know other frequencies and modes.[] Maybe the TV show didnt arrive in the UK till early 80s.

[JBL4645]

The Common Man is mostly horn with the odd boom, boom tympani. They did a pop version in the 70s for the Olympics. It was in the UK chats for several weeks!

The best version of "Common Man" I have heard is on Crystal Clear records' "Sonic Spectacular." While it has the brass you mention, the tympani, bass drum and tam-tam are overwhelming! There is a desk in the path of my speakers (quite a ways away) and the power of the tympani & bass drum throw it temporarly out of square. This may illustate the point that measured SPL isn't everything .... another version of "Man," on Reference Recordings can be adjusted to have equal SPL as read by a meter ("c" "fast"), but doesn't have near the force, wind, or emotional impact. I think this is because the Crystal Clear version had better micing on the percussion, and the recording had more content in, perhaps, the 40 to 80 Hz range.

Between 40/80Hz I would say seems right. I do have version of this on CD-RW a friend recoded it around early late 99 to early 2000. Id have put it though Spectrum Lab and see what computer makes of it.