I have been wondering why gun shot or explosion on movie doesn't have impact like real life. To me, a sound generated by popping balloon seems have more impact than gun shot from movie. Out of curiosity, I measured peak level of sound output when I popped balloon. It was 127db (with fast response & flat weighting). Can home audio system generate 127db peak?

If not, what is the limiting factor? Amplifier? Speaker?

With my calculation (assuming speaker sensitivity is 90db per watt). Apm will need to generate about 5000 watts for short period of time (I have no idea how long should be. 10 ms? or 100ms?) and speaker need to output that level without compressing dynamic range.

Anyone, can answer my question?

Thanks,

Well, how close did you measure the balloon? If you placed a meter right next to a speaker, it MAY be possible to at least reach 127dB. The speaker sensitivity is measured at 1 meter.

Can home audio system generate 127db peak?

If not, what is the limiting factor? Amplifier? Speaker?

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The reason why these sounds don't have the same effect is because most of the time they're not real sounds. They are generated by synthesizers and other objects that sound kind of like the real thing. I think everyone has heard a real car accident. They sound terrifying in real life. In a movie they sound like a mixture of cannon shooting and glass breaking. Not to mention the incredibly fake tire screeching. This is because a sound effects team will get together and make all the sounds the movies need using any means possible to stay in budget. So they'll take a log and smack it against maybe an old car door and drop a glass vase at the same time and presto, you have a car crash. Some movies are way better than others. Most of the time effects teams make what they think is a better sound than the real thing just to add to the wow factor. Just like the visual effects team makes actors appear to do impossible stunts. They will make people who get shot by a gun get that OMG look on their face and continue to stand and look down at their wound and then fall down for enhanced dramatic effect when in real life the person would fall instantly in most cases. Most of the time it's not the volume of the sound of the explosion, gun shot, car crash that makes it seem fake. It's the fact that you can never replace the sound of the real thing unless you record the real thing, and that would cost tons of money to do.

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I guess you mean all depends on system. But do you have more data?

For example, if rated power of amp is 100w (RMS), how much power it can generate instantly for typical consumer grade amp? 1000W? 2000W?

I am gussing it is more like speaker to be limiting factor since speaker cone physically have to move greater distance.

Well, how close did you measure the balloon? If you placed a meter right next to a speaker, it MAY be possible to at least reach 127dB. The speaker sensitivity is measured at 1 meter.

I put my RTA very close to balloon (about 4 ~ 5'' ).

For example, if rated power of amp is 100w (RMS), how much power it can generate instantly for typical consumer grade amp? 1000W? 2000W?

I am gussing it is more like speaker to be limiting factor since speaker cone physically have to move greater distance.

Better system, more power.

My IB will sustain 125 dBs and shake the house. Yes an earthquake in a movie can feel like a real earthquake in my house.

Im still trying to get that 130dB gunshot...its a little more difficult because most mains dont have that kind of output and most subs are not designed or EQed to do that, Im now building monitor mains with 12" high end woofers and 500W driving just those woofers...Im hoping for 90-120Hz range having 125+ dB if needed.

Better system, more power.

My IB will sustain 125 dBs and shake the house.
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Im still trying to get that 130dB gunshot...its a little more difficult because most mains dont have that kind of output and most subs are not designed or EQed to do that, Im now building monitor mains with 12" high end woofers and 500W driving just those woofers...Im hoping for 90-120Hz range having 125+ dB if needed.


That's pretty impressive. Can you show your system?

You mentioned 90-120Hz range. How about mid-high freq? Are you just focusing on low? Or is it easy to get high output on mid-high freq. range?

When I measured sound of ballon pop ( I don't have a gun, and even if I did I can't record them ^^ ), my RTA shows even distributed output on all freq.

How about recording sound of drum? Isn't drum can reach very high output? Did any have actual data or measured it? Can some audio expert answer?

Thanks,

The intended maximum sound level is 105 db for the full range channels and 115 db for the LFE channel at the listening position. Most people find this too loud. Most home systems are also incapable of reaching these levels. Anything greater is beyond what was intended and has a greater possibility of damaging your hearing.

Yes there certainly are systems that can do that. The amplification is robust, as are the speakers.

Haven't you ever been to a rock concert? Instant ear damage there, and you can get pretty close to gunshot loud. But again, unless you want to be wearing ear protection all the time in your home theater, it's not something you really want to be listening to at all regularly.

Instant ear damage there

Uhm...most concerts are not THAT loud. Though, after a half hour, permanent damage can occur.

Also, I have heard that gunshots can hit 160 dbs. Concerts generally do not go above 120 dbs.

Uhm...most concerts are not THAT loud

Yes actually they are. *always* wear ear protection if you go to a rock concert or a loud venue.

Concerts generally do not go above 120 dbs.

And you make my point for me. 120 causes permanent damage very quickly. You can't have ANY exposure above 115dB according to OSHA, NIOSH, ANSI and EPA.

The NIOSH exposure time at 115dB is 28 seconds.

I did hit 128 db @ 5 feet full range (just playing rock music) and let me tell you that, that was f***** loud my ear did ring for 3 days :o i know next time i will wear ear plugs and i only tried for 30 secondes, you will need alot of power and very efficent speakers for sure IE 105 db/watts and couple kw :D
here a calculator you can use, just do not need 3 db headroom just the purpose here http://www.crownaudio.com/apps_htm/designtools/elect-pwr-req.htm

Uhm...most concerts are not THAT loud. Though, after a half hour, permanent damage can occur.



Also, I have heard that gunshots can hit 160 dbs. Concerts generally do not go above 120 dbs.


Of course the are not that loud other wise they would be sued left and right for earing damage.

You can't have ANY exposure above 115dB according to OSHA, NIOSH, ANSI and EPA.

The NIOSH exposure time at 115dB is 28 seconds.

My understanding is damge (and human perception of loudness) is alwasys depends on dB and duration combined. 10 ms of 120 will feel less louder than 115dB for 28 seconds.

I guess you mean all depends on system. But do you have more data?

For example, if rated power of amp is 100w (RMS), how much power it can generate instantly for typical consumer grade amp? 1000W? 2000W?


No more than a little over 200W into the rated load impedance for a square wave at a single frequency. Less for other wave forms. With two frequencies receiving equal power (and therefore voltages) you'd only get 50W total out of it before the amplifier clipped.

Basically, the power supply rail voltage is going to be just high enough to accomodate a little power supply sag (from transformer regulation), the amplifier diode drops, and the sqrt(2) * RMS voltage peak of the sine wave it's rated for. A sine wave has a 3dB crest factor (difference between average and peak power) so you'd get twice the power out for a square wave with a 0dB crest factor.

With conventional amplifiers, any more would mean dissipating more power across the output devices at low power (that whole V^2/R thing - a higher possible output means the amplifier has a bigger voltage drop at low power between power supply rail and output so it generates more wate heat) meaning more/bigger output devices and/or heat sinks.


I am gussing it is more like speaker to be limiting factor since speaker cone physically have to move greater distance.

At low frequencies where the driver is not loaded by a port or passive radiator excursion is likely to limit you (air moved must quadruple for each octave decrease in frequency), especially in ported or open baffle enclosures. At high frequencies you'll run out of power handling and have thermal compression before you get there (more power may even make the system less loud due to resistance increases from voice coil heating).

Yes actually they are. *always* wear ear protection if you go to a rock concert or a loud venue.

I DO wear ear protection at concerts...I do not know why more people dont. but in theory, you can take 30 minutes of 120 db before permanent damage occurs.

I have hit 116 dbs with rock on my system....it was really loud, and I even had hearing protection on at the time. Actually, I think it was louder, because my spl meter is screwing up.

A good midrange setup can do 115dbs, but humans and animals can tell real sounds from amplified sounds.

but in theory, you can take 30 minutes of 120 db before permanent damage occurs.

What the heck theory is that!?

What the heck theory is that!?

Some theory....I did a google search and could not find where I had seen it...maybe I was wrong.

You guys cannot look at OSHA criteria for noise exposure for cases like this. The OSHA limits are based on a LIFETIME of working with those levels of exposure. They also do not represent a level before hearing loss. They represent a certain percentage chance of a certain level of hearing loss.

They have zero to do with hearing loss caused by occasional exposure to loud noises.

To the OP, all I have to say is, do you really expect that kind of dynamic range from movies? Seriously? Because if you do, then things like depth charges and things would literally implode your house. Or how about the rocket launch in Apollo 13...NASA estimates that a rocket launch is over 210 dB...at which point the sound wave behaves like a compression wave instead and would be instantly fatal to a human being. See how ridiculous we can take this? :D The impulse level from a gunshot varies dramatically by weapon used but is generally over 140 dB. I don't honestly think that anyone really wants to have that in your house, including you. I certainly don't want to have temporary threshold shift after every shoot-out in a movie.

EDIT -- in regards to the balloon burst, they can be surprisingly loud. Typically when I pop large balloons for RT60 measurements (when a room impulse response measurement is not possible), the peak level from the burst at a distance of 10-20 feet can exceed 105 dBA.

To the OP, all I have to say is, do you really expect that kind of dynamic range from movies? Seriously?
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EDIT -- in regards to the balloon burst, they can be surprisingly loud. Typically when I pop large balloons for RT60 measurements (when a room impulse response measurement is not possible), the peak level from the burst at a distance of 10-20 feet can exceed 105 dBA.

Of course no. I don’t want to hear actual gun shot from my room. It will be too scary ^^.

However, I think sound of gun shot on typical movies are too weak. It is not much louder than other sounds which is very unrealistic. I was thinking if special effect like gun shot and exposion have more impact, action movie will be more thrilled and fun to watch.

Most of dvd is recorded too loud to listen at reference volume. Shouldn’t conversation in movie have same loudness as real life at referance volume, and reserve enough head-room for gun shot or explosion?
That is why I am asking if dynamic range of home system can be MORE CLOSE (not equal) to real life. And try to find what is the limiting factor?

Most of dvd is recorded too loud to listen at reference volume. Shouldn’t conversion in movie have same loudness as real life at referance volume, and reserve enough head-room for gun shot or explosion?
That is why I am asking if dynamic range of home system can be MORE CLOSE (not equal) to real life. And try to find what is the limiting factor?


Do you think the original sound track has peak sounds (HUGE dynamic ranges) by design ie.. 120 dB gunshot? It might not be our systems at all. The original sound track may not even record the gunshot at 120 dB.

http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=standards&p_id=9735

They sure don't sound that loud on myth busters.

Do you think the original sound track has peak sounds (HUGE dynamic ranges) by design ie.. 120 dB gunshot?
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No, I don't think so. I like to know why they don't do that. Maybe they don't put huge dynamic range because home audio can't handle that dynamic range (which is my original question).

BTW, I measured again, and I got 118 db (I put RTA 1m away from balloon wiht flat weighting, fast response : 35ms).
If I understand correctly, it needs ~ 630 watts for 35ms on speaker with 90db/watt sensitivity.

I could use 500W dynamic peak on a 92dB sensitive speaker and get 118dB for more than a second. By this time I have ear protection and has little to do with enjoying the music but more to do with checking for a bad connection/setup calibration or just having fun. That is near 100dB outside with the door open and close to 70dB over a hundred feet away. The room is enclosed in concrete. This can also be done with two 125W, two 120W amplifiers and four 92dB speakers for me easy also. This was C-weighting on a RS meter. What kind of setup are you measuring with? The only way I can get more than 96dB measured in my RTA is if I change the dial to more than 80 or higher if needed. I'm not sure how accurate that would be changing the dial on the meter.

What kind of setup are you measuring with? The only way I can get more than 96dB measured in my RTA is if I change the dial to more than 80 or higher if needed. I'm not sure how accurate that would be changing the dial on the meter.

On my RTA, I can choose different ranges (30 ~ 90, 50 ~ 110, 70 ~ 130). I used flat-weighting (no adjustment like C or A).

No matter how capable your system is, you'll never get a realistic gunshot on a DVD unless they change the standards for how close a normal voice is to digital zero. There's just not enough headroom available on the disk above the SPL of a voice.

PS, gunshots are closer to 160-170 dB combined SPL when you add all the RTA bands together and the disk would have to handle peaks like that. See the diagonal labels for total SPL.

http://www.htguide.com/forum/attachment.php4?attachmentid=8135&stc=1

Thanks, Dennis. That's very usefull infomaiton to know.

I think DD track can have 144db dynamic range (correct me I am wrong). So if normal voice is around 70~80db, isn't there still enough head room to give powerfull feeling of gunshot.

Thanks, Dennis. That's very usefull infomaiton to know.

I think DD track can have 144db dynamic range (correct me I am wrong). So if normal voice is around 70~80db, isn't there still enough head room to give powerfull feeling of gunshot. Not really. The DD standard puts the loudest sound from a single speaker at about 105 dB with a 0 dBFS signal if you play the track back at reference level. And that makes the voices too loud for most people so they play it back at a lower level yet. If they are playing it back at -10, the loudest sound a speaker can make is 95 dB without the soundtrack clipping. Of course you have more than one speaker playing so the overall SPL is louder than that but you get the idea.

That said, I think you're right and they could mix the gunshots louder than they do. The puny popfffffff sounds they use for a gun are just silly but they're probably mixed for TV speakers and people who don't know any better. Most people have never heard a real gun and they have watched so many old cowboy movies where the guns make a pshewww-zingggg sound as the hero shoots and the bullet bounces off a rock that they think that's reality. :)

Edit: dynamic range relates to digital dBFS on the track -- the loudest and quietest sounds you can record on the disk. dB SPL is different -- how loud the sound is in your room. You can't compare one to the other directly. If a voice is 70 dB SPL and 0 dBFS (digital clipping) is at 105 dB SPL, you only have 35 dB of headroom above the level of the voice.

Do you think the original sound track has peak sounds (HUGE dynamic ranges) by design ie.. 120 dB gunshot? It might not be our systems at all. The original sound track may not even record the gunshot at 120 dB.

I think I found possible answer to my question recently. I was playing “Call of Duty: World at war” on my Xbox, and Gunshot on that game feel powerful. I never heard gunshot that powerful on any other movies or games. I decided to measure it with my RTA (fast response 30 ms + flat weighting). It was hitting up to 103 dB with -11dB on my receiver. Even with 103dB, it sounded pretty loud enough to scare me :).

So my conclusion is gunshot on movie doesn't sound powerful not because my system is under powered. It is because dynamic range of audio track on DVD is compressed too much. Reading some other threads, it seems current CD release are heavly compressed in dynamic range too. It is kind of disappointing trends to me...