Storm sounds

[Renton Maclachlan]

I mentioned on another thread about some storm sounds I've put with a video clip of a ship at sea. I've downloaded about six tracks of storm sounds...wind, rain, thunder...and have put them with the video and it does add to the flavour of a storm at sea.

However, I've noticed that the thunder seems to lose its intensity when mixed with the other tracks and when I showed the finished video to a group last week...on a dvd I cut for the occasion...on a TV owned by one of the group, the thunder hardly featured at all.

I would like the thunder loud but even with the volume up on the thunder tracks, it doesn't sound that impressive.

The volume on the thunder tracks is getting up into the red so may be clipping...not that I know much about clipping...

Any thoughts?

[Steve House]

Might be simply a lack of bass response on the TV used for playback. Instead of increasing the volume of the thunder tracks to the risk of clipping, reduce the levels of the other tracks to make room for the thunder.

[Roger Gunkel]

If you are using compression or limiting on the overall audio tracks, then the loudest sounds will be squashed down to the audio ceiling that is set. This often means that the lower sounds take a more noticeable part of the overall volume as they are lifted and the higher ones such as bass frequencies will get squashed down more, losing prominence. Sounds like that could be happening here.

Think of it as having waves in a glass topped tank, the less the gap between the water surface and the tank top, the more the highest waves will be limited.

You can reduce the overall volume to prevent peaking, but increase the limit level or reduce the compression to allow more of the squashed frequencies to come through.

Roger

[Greg Miller]

It's very likely that Mr. House and Mr. Gunkel have each described part of the problem, although we'd have to hear your actual tracks and evaluate the specific TV to be certain.

I'm curious about the thunder tracks that you're using. There is a very wide variety in actual thunder sounds. Thunder of a nearby lightning strike has quite a lot of HF energy, but the rumble of distant thunder has very little; it is almost entirely very LF in content. So depending on the spectral content of the particular thunder tracks you're using, those tracks might or might not reproduce well through a typical TV without any subs to cover the VLF range.

Are you trying to reproduce the sound of distant rolling thunder, or the thunder crash of nearby lightning strikes? Are you trying to do this under dialog, or is the thunder supposed to be a foreground sound accompanying (or shortly following) visuals of specific lightning strikes? The solution to your problem might depend somewhat on what you're trying to achieve.

Your recipe might be too salty; it might need more pepper. You might need a little more yellow in your paint, or maybe it has too much red. It's very difficult to evaluate taste, or visual appearance, or -- in your case -- sound, with only verbal information to go on. Can you let us hear any of the FX tracks you're using? Can you let us hear the problematic portion of your mix?

[Warren Kawamoto]

I think it's all about balance. If thunder is already in the red, you can't make it any louder. The solution, then, would be to lower the levels of the other effects. You can't add more water to a cup that's already full.

[Greg Miller]

Balance, but on what playback system?

*IF* the FX he's using is all below 50Hz, and *IF* he re-mixes for a TV with a 4 inch loudspeaker, then when it gets played back on a better system the thunder might be overwhelming. Because of the frequency range involved, this cold be trickier than just achieving a good balance between dialog and a music bed.

[Renton Maclachlan]

Thanks all for the suggestions.
Attached find the combination audio track ...
No the sounds are not under dialogue...

[Greg Miller]

Thanks for posting that clip.

The thunder doesn't sound especially loud to me, listening on HD280 Pro cans. Basically, I think it's your mix. (It should be remixed anyway, to eliminate the clipping.)

Here are spectral views of two different parts of the clip. The green is taken from 6.0 to 8.5 seconds, where there is essentially no thunder. The red is taken from 21.5 to 23.8 seconds, where there is continuous thunder added to the mix. There is a lot of energy between 100 Hz and 200 Hz. There is also some energy below about 80 Hz, but it's significantly lower in level, so I don't think that (or the lack of it on a small speaker) is the main problem.

What's the goal of your project? Viewing on typical TVs with internal speakers? Projection in a theatre with a good sound system? The better you can define the final playback system, the more intelligently you can mix this.

If you remix, you might want to use a HPF on your studio monitors, rolling off below about 100 Hz. That might somewhat mimic the sound of cheap TV speakers. But be sure to listen again, after you've mixed, with your studio monitors flat, to be sure you don't have an overwhelming amount of VLF energy.

I don't hear anything that I would consider to be a nearby thunder crash. It sounds more like distant rolling thunder to me. In real life that would not be painfully loud or overwhelming. What kind of thunder are you trying to recreate? Just distant background thunder? Or are you trying to recreate a thunder clap that accompanies a bright nearby lightning strike?

Also, throughout the clip, the noise of the falling water seems to predominate. This may be realistic for a ship at sea (I've never been on a ship during a rainstorm) but it certainly makes the thunder sound less impressive to me. I feel as if I'm in the shower. Maybe less falling water would allow the thunder to stand out more from the constant background.

Keep in mind that if you reduce the falling water, maybe reduce the wind, reduce the dialog on other parts of the track, so that the thunder is much louder than anything else, then a typical TV with small internal speakers may not be able to handle the overall level of the louder thunder, let alone the frequency response. This all comes back to the question of your expectations about the final playback system.

Given that the thunder presently peaks at 0dBFS, and the other storm sounds peak at around -6dBFS, where were your dialog peaks?

Good luck!

[Renton Maclachlan]

Thanks Greg...appreciated.

I don't know enough about the technical side of audio to to understand quite a bit of what you've outlined...I don't understand the graph...as mentioned I haven't even got a grip on clipping! Better read up about it...

However I do understand there are competing sounds...which affect each other.

There is no dialogue at all during the duration of the sounds as posted.

I want loud (variable) wind, and I want the impression of a great deal of rain...torrential rain...your comment about 'being in the shower' probably captures it.

However, I would like close thunder (I think there are two spots where I thought close thunder would sound) to overpower everything else as it would in real life...a real crack etc as the lightening bolt fires... There is also distant thunder rolling along in the background...

Perhaps at the close thunder spots I need to reduce the volume of the wind and rain tracks to allow the thunder to dominate...will look at it...

Re the goal of what the project will be played on. Could be anything. Home TV, computer, projector/theatre setup...

[Don Palomaki]

Might be interesting to review storm scenes from movies to see how they did it; such as some in "Master and Commander: Far Side of the World."

Of course easier to do it in a theater with full surround sound and monster sized sub woofers. Flashes on screen timed to the thunder help.

[Greg Miller]

"Clipping" is when the level of the combined track exceeds 100% (which is equivalent to 0dB full scale or "0dBFS"). In the digital world nothing can actually exceed 100%. In practice, I (and many other folks) try to avoid any levels higher than -1dBFS ... EVER ... even on a final CD mix. (This avoids potential problems with overshoot in D>A converters and subsequent filter stages.) So if you see levels hitting 0dBFS that almost surely indicates there was some sort of problem.

A clipped waveform will have a flat top. This is easier to see with pure tones than with mixed "noisy" sounds like your track. Look at the attached .gif file. Here I started with a pure sine wave of 440Hz at -6dBFS. The first five cycles are unchanged. The next five cycles had the gain boosted by +7dB; you'll see that the waveform is no longer sinusoidal, it is clilpped or "flat-topped" at 0dBFS. The third five cycles had the gain boosted by +12dB; you'll see that the waveform is distorted further from the original sinusoidal shape.

Clipping produces distortion when played back. The worse the clipping, the worse the distortion. Play the attached audio file. I started with 5 seconds of pure 440Hz sine wave at a level of -6dBFS. That's followed by one second of silence, then another 5 seconds of tone, another second of silence, and a final 5 seconds of tone. All the tones were originally -6dBFS. But I raised the gain of the second tone by +7dB, so it is trying to reach a level of +1dB; however, it's impossible to have a level higher than zero, so this is slightly clipped. I raised the gain of the third tone by +12dB, so it is trying to reach a level of +6dB; however, it's impossible to have a level higher than zero, so this is more severely clipped. Listen to the difference in the character of the three tones. You will hear the increased distortion.

In the loud parts of your storm mix, your waveform frequently hits 0dBFS and is clearly flat-topped, so your levels exceeded 0dB when you were creating the mix. You should NEVER do that! When you remix this, keep an eye on levels. If you see anything hitting zero, stop and fix the problem.

You say you want the sound of a loud nearby thunderclap, but your tracks sound like a distant roll of thunder. The two are different sounds; a thunderclap has much shorter attack time and much more HF content, compared to the rather distant thunder you're using. You're not going to get the sharp, abrupt thunderclap using the sample that you have, unless you do a lot of processing. And frankly -- no offense intended -- (based on your comment that you don't even understand clipping) I don't think you have enough experience to do that easily.

It would be very hard to produce a track with thunder that sounds equally good on a small home TV speaker and also on a large theatre system with subs. There is much too much difference in the playback systems, in regard to frequency response and in regard to useable dynamic range. You might create a successful "universal" mix with dialog and music, and even with some less difficult FX tracks. But thunder, because of the extreme LF content and dynamics, is a very tough nut to crack.

I probably have some old movies here that have realistic storm scenes, but offhand I can't think of one, and don't really have time to look through all of them. Maybe someone else has more free time than I have.

Good luck. And start reading! I recommend the various books by Jay Rose; he explains things simply and clearly, and I've very rarely found a statement that I didn't agree with.

[Jon Fairhurst]

A good tool is multiband compression.

In general, low frequencies have large power (and high amplitude) and high frequencies have lower power and amplitude. With normal compression, when the signal has a high level, the volume is reduced. This ensures that the peaks don't clip, but it can create a "sucking sound" when things get loud. With multiband compression, you can reduce certain frequencies (typically the lows) when things get loud. The effect is that things can get louder and louder, but the sound gets a bit thinner. Overall, this sounds more attractive and much more powerful.

This could be perfect for thunder. As mentioned above, the initial crack mainly has highs while the echo has lows. Frankly, this could be due to multiband compression already applied upstream in a good sound effects file. In the real world, a nearby initial crack can rattle a house! Our recording and playback systems don't have quite as much power as a bolt of lightning.

Anyway, the more multiband compression you have, the "louder" you can make the effect.

I would also recommend zeroing out any other sounds that might exist during the crack. Nothing competes with a lightning strike. One can use a side chain in compression so that when one source gets loud, other sources get quiet. But why bother setting up and adjusting a side chain? This isn't a case for subtlety or a long, automated track. When it comes to a lighting strike, it zeroes out rock, paper, scissors, rain, wind, dialog, and everything else. :)

[Jim Andrada]

Of course you could use a sheet of plastic to make the thunder like they used to do in the "good old days"

(Google "thundersheet" if you're a "youngster")

[Jon Fairhurst]

And for wind, you can use a dull whistle into a microphone. As I recall, I used three layers in the following video. I cut the playback rate of one of the tracks in half and applied various EQ to get the effect.

The coolest thing about making your own wind effects is that you can give it personality. It can rise as you enter a scene, fall during a dramatic moment, etc. One can consider it to be an active character.

I have yet to try recording rain. I'm sure that the watering can on a hard surface would work, but it wouldn't work for drizzle, driving rain, or a typhoon.

One thing to keep in mind is that we don't want films to sound like reality. We want films to sound like we imagine reality to be. :)

The Last Outpost on Vimeo

[Greg Miller]

Originally Posted by Jim Andrada

Of course you could use a sheet of plastic to make the thunder like they used to do in the "good old days"

No, no ... that was the new old days. In the old old days (before plastic) they used a sheet of tin. Or thunder balls, rolled down a metal gutter backstage, also imparting some directionality to the thunder.