@caveport Thanks for the reminder. Unfortunately it's too late for me to update my post but I will add to the wiki tomorrow. Cheers.

@douglashorn First off, muchos gracias for taking the time to respond with thoughtful feedback. Your contribution is essential to the enhancement of this topic.

I completely agree with you regarding the importance of "listening". I would go further and argue that someone with zero experience as a sound(wo)man would benefit immensely from buying a cheap eye mask, the type you wear on a plane to sleep, and spending a day wearing it in different locations just to experience and appreciate their surroundings from a sonic perspective.

Riding levels is definitely part of the techniques a sound person needs to employ to perform their function optimally. The complication arises from knowing when an adjustment to the gain setting is justified versus allowing a drop or increase in level due to the natural dynamics of speech in three dimensional space. My feeling is that this is a decision made largely based on experience making it difficult to impart any advice to persons whom this thread is intended for, i.e. indie filmmakers with very little or no experience with sound. This complication is further compounded by the impractical implemementation of gain settings on many cheaper recorders, i.e. access through a menu and modification by pushing buttons rather than twisting a knob. I would love to hear from seasoned pros on the subject.

I want to make absolutely clear, in the event it wasn't in my previous posts, that I am NOT, in any way, shape or form, an authority on the topic of location or post-production sound mixing. I don't make a living from it and, compared to others actually working in the industry, have very limited practical experience. However, on top of the 20+ years of music recording/mixing experience I've accumulated combined with the multitude of shoots I've been on in the last 4 years I feel I've developed a certain "philosophy", in the pure sense of the word, that may have enough value to share with others given the dearth of information on this topic. This is a long-winded, yet important, preface to my next point which is that I cannot offer any advice on the placement of lavalier microphones as I really don't have enough experience with them to elaborate on the topic. However, I whole-heartedly encourage and urge those with relevant experience, such as yourself, to contribute to this thread so that we can expand and enrich its content. Again, I will be happy to modify the wiki with all positive contributions that add to the knowledge base.

Great stuff @spacewig ! You should put this together on its own blog page somewhere for filmmakers to read since this covers many perennial questions really, really well. (I'd love to have this as a guest post on my filmmaking blog if you don't have better options.)

A couple thoughts: When one is running sound, it is crucial to listen. Sounds simple, but I think that's where a lot of DIY filmmakers get in trouble by paying more attention to the levels meters than the actual sound. Listening to rehearsals and prior takes really helps in setting proper headroom (knowing whether a big outburst is coming up in a quiet scene, for example). At the same time, it's frustrating in post when the sound dynamics change significantly between different takes or angles of the same scene--which makes cutting these together a challenge--so maintaining consistency is equally important. Sometimes it's better to "ride the levels" or just record a second track at a lower level to cover the yelled portions.

Labeling/naming tracks and using the "Slate mic" functions of better recorders is such a nice treat for post. As is keeping a good log of tracks to give to the editor (this is often done in conjunction with the script supervisor). These are the organizational grace notes that make an enormous difference on large projects like feature films and series.

There's also a lot of experience involved in selecting and placing lavs and wireless packs so they don't rustle or appear visibly. I'd love to hear your advice on that.

1, 2, 3, 4, 5... SUPER Comandante Espacioooo!!! +)

@spacewig Thank you for all the effort

10) OK people, this is THE most critical component to ensuring smooth, flowing dialogue transitions in your film. In a perfect movie, dialogue doesn’t explain WHAT your characters are doing but WHY they’re doing it. That makes the dialogue mix crucial to the story. And anything that takes your audience out of the story, like a fumbled/mumbled word, set noise, rumbling stomach, sneeze, sniff, etc. needs to be corrected. Roomtone is the sonic glue that allows you to slice/dice/fix/nix dialogue issues transparently. If you have not recorded roomtone during your shoot you will be forced to create it from whatever snippets of silence you can find in your dialogue tracks. This can be a very long and extremely aggravating procedure; and you will need to do it since roomtone is absolutely essential to post-production dialogue editing. You cannot simply go back to the location and record ambient sound as the sonic character of the set will most probably have changed significantly by then making any such recordings useless.

What is the easiest way of acquiring roomtone? Easy. If you are the director, make sure for each shot that you WAIT AT LEAST 3 SECONDS BEFORE CALLING ACTION after your gear has started recording. Five seconds is even better, eight fantastic. Ensure that everyone (actors, crew, producers, investors) involved in the production on the set knows from the outset that for the few seconds prior to action after the camera starts rolling everyone has to be dead silent, i.e. no whispering, moving, sniffing, scratching, etc. For example, when you’re ready to do your first take shout “Silence on the set”; once everyone is quiet tell the soundman to “roll sound” then the camera operator to “roll camera” (they should each confirm by replying “rolling”) then count a few seconds in your head, visually queue the slate person to call the shot and once he/she’s out of the frame call “action”. You’ll regret not having made this simple but time-saving effort during post.

8) This is where a lavalier mic comes in handy. They allow you to mic the talent and capture dialogue where the use of a boom is difficult or impossible. There are a few downsides to using a low-budget lav setup, however, which relegates them, at least in low-budget narrative filmmaking (or where you want to recreate reality as closely as possible), to worst-case-scenario status. Lavalier microphones have an omni pickup pattern which means they capture sounds coming from all directions; they don’t exhibit the same frequency response curve as a shotgun/cardioid mic and because of their proximity to the mouth sound very dry and clinical which makes them a challenge, but not impossible, to match in post; they have to be wired to a separate recorder (more gear/batteries + syncing in post) unless you use a wireless transmitter which also implies more gear/batteries - plus transmitters also have their own issues notwithstanding the fact that they don’t have as wide a frequency response as a hard wired setup unless you’re using very high end gear = $$$. Within a low-budget filmmaking context lavs are best used to complement a shotgun (for intelligibility) or when you have absolutely no choice.

6) Inverse Distance Law (1/r) is the physical principle used to describe the propagation of sound pressure level (SPL) from a sound source as it relates to the distance from that source at which the SPL is measured. In a nutshell: It states that if source A has an SPL (measured in db) of X from Z ft/m away, it will have an SPL of X/2 (½) from 2Z ft/m away, X/3 (⅓) from 3Z ft/m away, X/4 (¼) from 4Z ft/m away… etc. In other words, the SPL drops by half (6db) per doubling of our distance to the reference SPL measurement.

What’s important here is not how loud the source is (the actor speaking his/her lines), but how much gain you have to apply to the signal (coming from the microphone capturing the dialogue) to get an average reading of -20db. Let’s go back to John and Jane for a practical example:

You are recording an over-the-shoulder shot of Jane speaking with John. The shot is framed tightly enough to allow you to hover your boom approximately one foot away from her head without the boom dipping into the shot. You adjust the preamp gain so that your meters are reading at least -20db when Jane is speaking. Perfect. Now the director’s moved to a two-shot which is wider but because of the camera angle you cannot get your boom any closer than 4 feet from the actors without it getting into the shot. The inverse distance law above tells us that Jane’s voice will now be 12db quieter, i.e. the average level of her voice on the meters will be -32db. Your two immediate options are to either record at -32db then raise the levels in post which, as discussed above, means that you’ll also be raising your recorder’s noise floor by 12 db; or you can simply increase the gain 12db on your preamp which will bring the levels back up to -20db. While this might sound like the no-brainer solution to your sound level drop, there is a catch.

More noise. But this time from 2 different sources: the rest of your recording kit and your location’s ambient sound. Your mic, like your recorder, also has self-noise that is increased in direct proportion to the amount of gain you apply to the mic’s signal. Same with your preamp (though most modern opamps have inverse noise/gain characteristics, but I digress). So, on top of the recorder’s SNR you also have to contend with the noise inherent to the mic AND the preamp. A remedy is having a mic and preamp with the lowest noise-floor possible (this comes at a cost) and choosing a mic with a hot output (produces a stronger signal than other mics for an equivalent sound pressure level) allowing you to apply less gain.

Ambient sound, also known as roomtone. People exist and interact in environments that are teeming with ambient sound. While you might do your best to minimize blatant BG noise from contaminating your set, unless you are recording in an anechoic chamber there will always be ambient sound present and surrounding all environments you record in. The difference between ambient sound and BG noise, in this context, is that BG noise is usually directional and comes from a source over which someone has some kind of control. Ambient sound is simply there and cannot be altered by human intervention. i.e. rain, thunder, ocean, highway traffic, parade, city din, etc. Its not evil, its just there. Everywhere. Why should you care? Because the ambient sound of a given location exists at a level that is usually the same no matter where you place your microphone. This means that when you raise the gain by 12db for Jane’s vocal to average -20db on the meter, not only have you increased the noise but you’ve also just raised the ambient sound in the recording by an equivalent amount relative to the dialogue, i.e. the roomtone in the two-shot of Jane will be 3 times louder than it was in the over-the-shoulder shot. You can, and should, choose a location exhibiting the lowest ambient sound, but you will still get this disparity when your subjects are at different distances from the mic.

This might all seem overwhelmingly confusing but the practical bottom line is this: Get your mic as close to the person speaking as humanly possible WITHOUT getting the mic in the shot. What if its a wide shot and there’s absolutely no way to get the mic closer than 5 m/yrd from the actors using a 15 m/yrd boom?

4) Prior to principal photography ALWAYS scout the locations you’ll be filming at to determine what background (BG) noise issues you’ll be facing. Fridges, ventilators, generators, clocks, computers, phones, neighbours, pets, kids, trains, planes, motorized vehicles, lawn mowers, construction, neighbourhood bars/clubs, the ceramic tile company running machinery 9 to 5 down the street, etc. need to be identified in advance as they all have the potential of being picked up by your boom/lav and ruining your takes. Is it impossible to shoot with this noise present? No, you can always attempt noise reduction (NR) and/or spectral repair (SR) during post-production or you can replace unusable dialogue with ADR sessions but this adds a major bottleneck to your workflow. Will your actors be available for ADR? Are they capable of reproducing the same emotion(s) and tone(s) of the takes you’ve decided were keepers? Be warned: ADR is nowhere near as easy as managing BG noises of your locations and even choosing locations in advance that have the least probability of suffering from these issues. Assuming BG noise sources are within your control, simply making sure you can turn off/unplug offending devices during your shoot will make post that much less of a pain. As for NR/SR, keep in mind that these processes degrade the quality of your audio, usually to a degree proportional to the amount of correction to be made. Less processing = greater fidelity.

2) Your recordings never have to exceed a 48KHz sample rate at a bit depth of 24 bits. Anyone who tries to convince you of the contrary is full of shit. As a matter of fact, you won’t hear the difference between that and a recording captured at 16/44 i.e. CD quality. If someone you know insists that 24/48 is substandard and they can hear the difference between that and audio recorded at 24/96 or 24/192 have them listen to file "Tone 1" below. If they can’t hear anything play file "Tone 2" for them. If they still can't hear anything and complain that the files are silent (and they’re not, just look at your meters while they’re playing) have them listen to file "Tone 3", which is as loud as files 1 & 2, then change the subject because you’ve just invalidated their pretentious claim.

I am not trying to start a flame war nor will I entertain any discussion regarding this hot-button topic. I merely want to prevent my fellow filmmakers from being conned into buying pricier gear offering settings they will never need, or of recording tracks using sample rates that will create unnecessarily large files and will likely incur a CPU overhead penalty when it comes times to mix. The clear advantage of 24 bit over 16 bit is that you have ten times the amount of values to represent the signal you've recorded which means rounding error artifacts (quantization noise) created when processing the files (noise reduction, spectral repair, reverb, EQ, deverb, etc) will remain firmly buried in the noise floor. In other words, they’ll be inaudible. As for the advantages of 48 over 44.1KHz, the file sizes are the same so might as well take the extra, though mostly negligible, smoothing of the audio signal this gives you. To summarize: Audio captured at a bit depth and sample rate greater than 24/48 will NOT sound better.

1. Gear: Mic, cable(s), preamp/recorder, batteries, memory card, boom pole, shock mount, earphones, slate
2. 24/48
3. Make sure your gear works
4. Scout locations
5. -20db
6. Inverse Distance Law
7. Sound perspective
8. Lavalier microphones
9. Slate
10. Roomtone

Small update: I'll soon be finished item 1, location sound, and apologize its taken so long but that topic alone is a massive undertaking as far as covering key PRACTICAL concepts. It feels like I'm writing a book sometimes but I don't want to make propositions without supporting them, even if only superficially. Stay tuned.

@DrDave I suspect your audio expertise will find many opportunities to expose itself in this thread ;)

Well, not sure what you mean, and it is quite possible I am mistaken. However, here is the license for Audacity "Audacity is free software. You may use it for any personal, commercial or educational purpose, including installing it on as many different computers as you wish." Note that the license includes the phrase personal, commercial or educational. Most Eula's do not. For this reason, I recommend using Audacity or similar products for your workflow. Or, at the very least, including it as a hassle free option in a workflow description.