yet again another sound question from me

B

brettzdamn

Ok i just received my zoom h4 and was conducting some tests with it. I noticed that when imported to my pc the sound on my zoom is alot lower then the sound my camera produces with the internal microphones. So when i was in adobe premiere looking at the audio clips i raised the dB and it made the audio track louder. Does any one know what dB stands for? Also does this effect the quality of the audio or just the volume? Thanks in advance for any one who can help me!
 
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It's either decibel, or DaBoom. Here's a wiki link with alot of science mumbo jumbo.

http://en.wikipedia.org/wiki/Decibel

In it's proper form, it's used as an expression of gain ratio. Less in not always bad, and more is not always good. In most uses in audio for film or video, it is used to describe the level of a signal. Since nearly all sound in film is a complex waveform (other than reference tone), comprised of what we want, and also what we don't want, the idea that simply using gain to get more of what you want and less of what you don't want typically fails in frustrating manner.
Where gain affects quality is when stepping up gain structure of a signal path, and the only reason for it's affect is that proper gain staging permits components and circuit to operate at their optimal level (which is different for different equipment) and thereby minimizing the self-noise induced by the circuit.
 
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brettzdamn said:
Does any one know what dB stands for?
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The decibel (dB) is a logarithmic unit that indicates the ratio of a physical quantity (usually power or intensity) relative to a specified or implied reference level. A ratio in decibels is ten times the logarithm to base 10 of the ratio of two power quantities.

http://en.wikipedia.org/wiki/Decibel


A little research on your own doesn't hurt, you know.

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Raising the dB level of an audio clip makes it louder and does not change any of its other properties (unless you try to increase the sound byte volume over 0dB, in which case you will induce digital distortion and/or digital clipping and/or aliasing). If the sound byte is noisy, when you raise the volume by 20dB (for example) the dialog and the noise both get louder.

The reason the volume is low with the Zoom H4 (and the H4n, the Tascam DR-100 and similar very inexpensive audio recorders) is that they are intentionally made that way; they are primarily marketed to musicians who as a matter of course work at much higher dB levels and routinely distort their recordings. The internal mics and mic pre-amp scheme are set up so that the unit can be placed in front of a band that wants to record a rehearsal, for instance. The drummer is going to pound as heard as he can, the bass player will play as loud as he can, the guitarist has no comprehension of the term "Turn it down!" and the singer will be screaming at the top of her lungs into a $150 PA system, all in someones living room. The way the unit is biased by the mic/pre-amp scheme plus the compressor/limiter means that they won't have to turn the unit down to capture an undistorted recording.

As an independent filmmaker you will be capturing dialog; 75% of the time will it be at normal speaking levels, 10% will be screaming and 15% will be whispering or soft speech. Only the screaming will come close to the dB levels the unit was designed to accommodate. The unit also has (in digital audio terms) a very high self-noise floor (hiss) that would go unnoticed by a musician, but becomes all too apparent to those capturing more subtle sounds.

Digital audio recorders like the Zoom H4n, the Tascam DR-100 and similar units are popular with the indie film crowd because they are cheap, not because they record production sound well.

As I mentioned, for $100 you got a nice deal. But as with all ultra-micro-budget acquisitions you are going to have to deal with the problems as well as the benefits. You can raise the dB level without affecting the quality of the sound either positively or negatively (unless you distort it as mentioned previously).

One more piece of info while we're at it... Always get the mic in as close to the source a possible.


The Inverse Square Law

In simple terms, this means that a sound twice as far away is only one-fourth as loud. A sound four times as far away is only one-sixteenth as loud. So a human voice that records with adequate volume two feet away is just one-sixteenth as effective at eight feet.
 
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Alright yeah thanks man. I love it that you know everything about audio =) Also even if down the road i get a nice shot gun mic to attach to it, will the sound be louder? also i only upped the dB from 0 to 6 and their is no noticeable difference in quality, atleast for me.
 
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It will depend upon the mic, but, yes, the sound will be quieter with the H4 compared to other units like the PMD-661, HD-P2 and R-44. But even some mics have lower output levels when compared to other mics; the NTG-2 is notorious for low output levels, and when combined with the H4n you get VERY low audio levels. (It's funny, the Rode NTG-1 and NTG-3 do not have the same problem).

No matter what gear you get the quality of your sound will depend greatly upon your technique. As I constantly harp on in my posts, it's the cumulative little details that yield the quality results; details like matching the right mic to the right recorder, gain-staging, power usage (low batteries can greatly affect audio quality), and, most of all, boom technique.

So if you have a good mic into a solid audio recorder with optimum volume levels throughout your audio recording system, and your batteries are always fresh, and if you consistently aim the boomed mic overhead center/chest as close as you can to the actor delivering the line(s) you will have decent production sound. It's the boom technique that is hardest to learn and consistently practice, but all of the other details have immediate affect on the sound.

Just imagine how good your tracks would sound if you spent as much time setting up your sound as you do setting up the rest of the shot... And if you spent as much time on audio post as you do on editing...
 
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Alcove Audio said:
Just imagine how good your tracks would sound if you spent as much time setting up your sound as you do setting up the rest of the shot... And if you spent as much time on audio post as you do on editing...
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+1 ! Oh that has been something I have tried to tell people for soooo..looong. Get the sound right at the source firstly and the job gets so much easier. Then learn how to use compressors, limiters, EQ's etc "Properly" when editing and the audio will not be the poor cousin of the picture.
 
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rocksure said:
Get the sound right at the source firstly and the job gets so much easier.
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Getting that message out has been my mission for quite a few years now.

rocksure said:
Then learn how to use compressors, limiters, EQ's etc "Properly" when editing and the audio will not be the poor cousin of the picture.
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Here's a case of having too much of a good thing - "Properly" is the key word in this connection. It takes lots of experience and training (even if it is self-schooling) to learn to use these tools to best effect. But the biggest problem is the listening environment and the audio playback system. Your bedroom and computer speakers (even if they're good ones) create a lot of problems. You'll be using EQ to compensate for frequncies that are overly hyped (or underly represented) by your room and speakers. Compression can make things apparently louder, but can make them harder to blend into the mix.

Again, go for it, experiment and have fun. But keep in mind that eventually the proper audio tools costing tens of thousands are encased in a room worth hundreds of thousands.
 
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Alcove Audio said:
Getting that message out has been my mission for quite a few years now.



Here's a case of having too much of a good thing - "Properly" is the key word in this connection. It takes lots of experience and training (even if it is self-schooling) to learn to use these tools to best effect. But the biggest problem is the listening environment and the audio playback system. Your bedroom and computer speakers (even if they're good ones) create a lot of problems. You'll be using EQ to compensate for frequncies that are overly hyped (or underly represented) by your room and speakers. Compression can make things apparently louder, but can make them harder to blend into the mix.

Again, go for it, experiment and have fun. But keep in mind that eventually the proper audio tools costing tens of thousands are encased in a room worth hundreds of thousands.
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Yes true. Computer speakers in a poor room are never going to be good enough to really do justice to making informed decisions when working with sound. There is no substitute for proper studio monitors in a controlled environment.
A few years ago a wrote a brief tutorial on using compressors. Originally I wrote it to help a couple of guys I with a worked with in a TV studio and I was tired of fixing up their audio "mistakes". If anyone is interested I reposted it a couple of months back at http://soundrecordingtips.blogspot.com/
 
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Alcove Audio said:
The drummer is going to pound as heard as he can, the bass player will play as loud as he can, the guitarist has no comprehension of the term "Turn it down!" and the singer will be screaming at the top of her lungs into a $150 PA system, all in someones living room.
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Once you get the knob over 5 on the amp, you can turn it DOWN towards the higher numbers, because it starts pointing at the floor again, right? Or, my favorite, you've got a melodic bass player? All the guitarists should turn the bass knob on their amp way the hell up to bury him! This can work in reverse too, with a bass player walking all over the mids. And all rhythm players should play louder during solos of course...it's more intense!

As a related note, and I believe Alcove mentioned on another thread, make sure your dialogue is not all sitting at 0db. That gives you absolutely no room for foley and music. Intensity happens with dynamics (quiet sounds becoming loud and then quiet again). I've worked on too many films where the edit I've been given looks like it was run through a brickwall limiter (a constant roar around 0 to -6db). Louder is not always better (again, raises the noise floor too).
 
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JoshL said:
As a related note, and I believe Alcove mentioned on another thread, make sure your dialogue is not all sitting at 0db. That gives you absolutely no room for foley and music. Intensity happens with dynamics (quiet sounds becoming loud and then quiet again). I've worked on too many films where the edit I've been given looks like it was run through a brickwall limiter (a constant roar around 0 to -6db). Louder is not always better (again, raises the noise floor too).
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I think you either misread or misremembered what I posted. There has to be dynamic room above the dialog for score, gunshots, explosions and other loud sounds. Having the dialog top out at about at -12dB is dialnorm for most broadcast situations (as referenced on the LM-100), and, as I had mentioned, it's a good referential starting point for those new to audio mixing. I don't know anyone who has their dialog averaging 0dB. Georgia over at Nutmeg Post maintains that dialog should average around -20dB, my friend Questar over at Real Recording says -12dB is the way to go. Others I communicate with each have a different preference within that range. These are all very experienced, very respected folks with many years of audio post mixing behind them. They all agree, however, that this is only a starting point, and that your ears tell you what is correct, not a meter.

As as far as dynamics go I hate 99% of the music recordings I hear because they are overly compressed. I don't know where you're getting those squashed mixes, but whoever is doing it ought to be shot. With the exception if a limiter on the DX stem I very rarely use dynamics processing in my mixes. I will use a compressor on individual sound clips that I need to pop out or to tame an unruly sequence. My biggest "fault" is that my mixes tend to be overly dynamic, if anything; a large percentage of my clients seem to want a narrower dynamic range, so that is what I give them. And in the end, it's the clients wishes that pays the bills.
 
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so alcove To make it louder without messing with the dB what if i put it into a program like audacity and use the effect amplify? is that going to mess with the quality or give me white noise or anything?
 
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You're getting caught up on a conversation that is WAY over your head at this point.

Concentrate on getting solid clean dialog during production. When you get into audio post if you have to raise the dB level of audio clips, do so. Just balance out the dialog and eliminate noise as best you can, then blend in Foley, sound FX and the music. As you gain more experience and spend some time experimenting you'll start catching on to more advanced topics (dynamics processing, EQ, etc.).


Try this book; it applies primarily to music, but the concepts are similar.

http://www.amazon.com/Recording-Eng...867X/ref=sr_1_5?ie=UTF8&qid=1309452459&sr=8-5

The reason I recommend it is that most sound-for-picture books assume that you already know basic audio engineering. You can also try:

http://www.amazon.com/Sound-Effects...=sr_1_1?s=books&ie=UTF8&qid=1309452590&sr=1-1

Ric is a cool guy, and the book covers a lot of the basics.
 
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brettzdamn said:
so alcove To make it louder without messing with the dB what if i put it into a program like audacity and use the effect amplify? is that going to mess with the quality or give me white noise or anything?
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As Alcove said, "raising the dB level of an audio clip makes it louder" - you can't make something louder without affecting the dB measurement (not that that's a problem). As he also explained, it won't affect any other properties "unless you try to increase the sound byte volume over 0dB, in which case you will induce digital distortion and/or digital clipping and/or aliasing".

What increasing the volume in post will do is make everything louder - including the noise. Any background noise, power supply hum, self noise from the microphone that was once quiet will increase in volume along with the "signal", which is the stuff you want to hear.
 
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chilipie said:
As Alcove said, "raising the dB level of an audio clip makes it louder" - you can't make something louder without affecting the dB measurement (not that that's a problem). As he also explained, it won't affect any other properties "unless you try to increase the sound byte volume over 0dB, in which case you will induce digital distortion and/or digital clipping and/or aliasing".

What increasing the volume in post will do is make everything louder - including the noise. Any background noise, power supply hum, self noise from the microphone that was once quiet will increase in volume along with the "signal", which is the stuff you want to hear.
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ohh alright my only problem is in adobe premeire the audio can only go up to +6 dB should i raise and lower it in a different program?
 
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Alcove Audio said:
I think you either misread or misremembered what I posted. There has to be dynamic room above the dialog for score, gunshots, explosions and other loud sounds.
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Yes, which is what I said. Do NOT make everything as loud as possible just because you can. We're on the same page here ;)

And, yeah, I've been close to wanting to shoot bad sound mixers. My current least favorite is a short that for some reason they put a constant cricket chirp loop over (it takes place outside). Sure, my feelings were hurt when it buried the subtle moments of my score, but there were moments it buried the DIALOGUE (which was not maxed out, unlike some of this guy's other shorts). Hell, I think half the time I knew the score was there because I knew what it was supposed to sound like.
 
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