Audio Myths in the Production and Post-Production world.

The world of audio is surprisingly complex yet deceptively simple. When microphones work and cameras remain in sync It seems like anyone with a basic knowledge of production can run audio on set. However, it’s when things go wrong that it becomes painfully apparent how complicated audio can be. As an audio specialist, I regularly encounter myths involving the “cans and can nots” and “dos and don’ts” of audio. Below is a list of the most popular myths that seem to frequently come up in the production world. 

We can fix it in post.

Maybe, maybe not. This colloquial phrase is by far the most popular. Often said as a joke but all to often uttered in a state of desperation. The truth is complicated. The fact is that many audio problems can in fact be fixed in post. Noise reduction and audio restoration software is more affordable now than it’s ever been and certain companies have made giant leaps forward in developing algorithms that can detect and remove non-dialog sound without leaving artifacts.

However, it’s only the audio professional who actually knows which of these problems fall into the category of “fixable”. Moreover, while certain aural offenses CAN be fixed in post, there’s no guarantee at the time of production that they WILL be fixed. The production sound mixer almost never knows who will be editing the day’s content and whether or not there will even be an audio post specialist employed. It’s very common for video editors to miss very simple audio problems simply because they are tasked with the project’s visual half. By far, the most cost efficient solution is to always fix audio problems as they are happening prior to rolling a take. Then, if need be, consult with the production sound mixer as to whether or not the problem can be fixed (or at least reduced) in post.

It’s M.O.S., we don’t need audio here. 

This really depends on the type of project. In general you actually do need to record audio even for shots that you initially don’t intend to have production sound for. Narrative works are most commonly associated with projects that will take shots originally captured without audio and require diegetic (real to life) audio to be placed in at a later date. While it’s true that if the content isn’t dialog based it can then be recreated after the fact. However, having production sound for that “M.O.S.” shot, no matter how bad it may sound, can often be extremely valuable during post. Unless you plan to strip away every diegetic audio element from your shot, which is often done to great effect, you will need at the very least a guide track to build off of. Is the guide track absolutely necessary? No, Foley artists have been exercising their craft for decades without them. It’s mainly a matter of holistic time-management and cost efficiency on a project’s grand scale. If your sound mixer can grab a few footsteps here and there or a door opening or closing between the director vocally coordinating actors then that’s a few footsteps or doors that could possibly sound good enough to make the final cut. At least, it will help make syncing Foley easier.

We don’t have the budget for a boom op but we can give you a PA to hold the boom pole. 

Thanks but no thanks! Booming is an art form that takes years to get right. It may look like just holding a light weight pole above your head but the reality is that it is incredibly nuanced and requires both physical endurance as well as a keen understanding of blocking for actors, how actors project their voices, how they are interpreting the script, and when and when not to swing the pole to capture multiple lines on camera. The result of a PA or intern holding the boom pole is almost always an useable track of off-axis voice and low frequency rumbles due to improper handling. In the end, it will likely cost you more money then budgeting properly for a boom op.

We don’t need room tone

Yes you do! In fact, what you need even more than room tone are longer beats of silence directly before and directly after an actor or on camera talent finishes a scene or interview question. The tone of a room changes throughout the day. These changes are more notieable for exterior shoots but even inside a quiet room the recorded sound of an interior space’s ambient sound will alter throughout the day. This could be caused by anything from humidity to exterior sounds leaking in or changes to sound in adjacent rooms due to occupancy or appliances. That precious beat is better than the traditional 30 seconds of tone commonly captured at the end of a work day because it will sound more similar to its adjacent dialog. Thus, it is much more useful for mixing dialog in post. Also, giving a beat of silence after calling ‘action’ or delivering an interview question ensures that on screen talent don’t step on your words, which can be a nightmare for an editor to deal with.

You can use our gear. It’s as good as yours. 

This is almost certainly not true. While I would never consider myself a “gear snob” I am very reluctant to use a production company’s sound gear. The reasoning is simple. I can’t guarantee that it will work correctly. With digital audio equipment becoming cheaper then it’s ever been it’s common to find larger production companies with their own audio package. The problem is that there’s almost never anyone on staff that maintains this equipment specifically. Without an in-house audio expert it’s very easy to lose track of which cables were acting up, what firmware is the correct version to have on the recorder (it’s not always the latest one), and which wireless frequency blocks to use in various cities. As production sound mixers, our careers depend on maintaining perfectly working professional equipment that will work in any shooting environment. The reason you’ll see a sound mixer wheel in a large cart of equipment for a simple interview is because we need to be prepared for any unexpected request or scenario as well as supplying backups of every device we use.

If the newest recorders capture at 32bit why aren’t you always recording at that bit depth?  

The answer is complicated and better explained by my colleague Max Futterman. Read his explanation HERE.  

Creating A Sound-Friendly Interview. A Guide For Emerging Directors And Producers

Not all interviews are created equal. Some sound great while others are riddled with distracting noises. The great sounding ones allow viewers to really absorb what the interviewee is saying. The bad ones create a sense of confusing unease that result in the viewer losing attention.

Below is a guide for the emerging director or producer in steps that should be taken to ensure you have the best sound for your interview.

Choosing a location:

By far, choosing a quiet location is the most important task standing before you. The production sound mixer can only record the best audio that’s available in the space that the interview takes place in. A general rule of thumb is that if you can hear a distracting sound with your own ears then it will most likely be intensified when recorded through sensitive microphones. Having a hum in the background won’t necessarily ruin your interview but it could possibly make your life more difficult when you reach the editing stage. Don’t ever think to yourself, “we’ll be able to fix it in post”….the truth is, you really don’t know that for sure.

Here’s a checklist of questions that you should ask yourself prior to confirming your interview location.

Will you “own” the space? Will you be able to turn off refrigerators and air conditioners? Will neighbors likely be mowing their lawns and if so, are you prepared to either pay them cash to take a break or at least plead with them to stop? Are you in an office building where HVAC systems are controlled for the whole floor instead of room by room? If so, have you coordinated with the location’s owner or manager ahead of time so that you can speak to a facilities worker while on set? Does the office building use white noise machines to create privacy as some law office building do? If so, can they be turned off? Say your interview is with a chef in or near a kitchen? Is the chef willing to temporarily turn off the coolers, ice machine, and grill hood? Are you near a busy road or highway? If so, does your interview take place during rush hour? Is your location in a flight path and if so, how consistent are the planes? Are you prepared to stop frequently for the planes and will these pauses disrupt the flow of your interview?

I think you get the idea. The main thing to ask yourself is whether or not the location can be controlled. If you can’t get 100% confirmation on this then it may be best to choose a different location.

Creating a non-distracting environment:

You will often find yourself interviewing someone who’s never been in front of a camera. They won’t know where to look, might not be able to sit still, and in general feel uncomfortable in the setting. This is especially true when the content and subject matter of the interview is personal and emotionally sensitive. How does this relate to sound then? Creating a quiet, non-distracting environment is just one way that you can help put your interviewee at ease. Putting up dark sound blankets can work to both absorb sound and block distracting views. It’s also important to ask that non-essential crew members leave the room or at least move away from the interviewee. Keeping crew members away from the subject’s line of sight will also help retain a person’s attention. A general rule of thumb is that the more sensitive the subject matter, the less people you want to have sitting around listening.

A basic interview in mid set up.

Problems that could affect editing:

From an editing perspective, one of the biggest interview faux pas is when the question and response step on each other during a single-person interview. A video edit will happen at a single frame. If the end of an interviewer’s question overlaps the beginning of the subject’s answer then the beginning of that edited frame will contain an unintelligible sound from off camera. Editors will often cut off the very beginning of a word in order to work around this, which causes choppy and poor sounding audio. This problem can be avoided by simply reminding the subject to wait about 1 second before answering. This can be useful not only for sound purposes but also to give the subject time to think about a response. I’ve seen directors use subtle hand gestures to cue someone when to respond that seem to work well. Ideally, your conversation will flow naturally without overlaps and you won’t need to think too hard about this aspect. Your sound mixer should inform you when there’s overlap and then it’s up to you to decide whether or not you’d like to keep moving forward or run the question again. Another tip, which is more editorial based and not audio specific, is to make sure the subject begins their response in a full sentence. If you ask “What is your favorite color?” and they respond “Blue”, all you’ll have is a single word out of context during the editing process. They need to respond by saying “My favorite color is blue.”.

All this of course assumes you’re working on a single-person interview. For “60 Minutes” style interviews you won’t need to worry about overlap as both people are on camera. The viewer can see and hear the question and the overlap won’t be out of place.

To lav or not to lav? The standard micing set up for an interview is to use both a boom (overhead) mic and a lavaliere mic. You’ll only use one or the other during your post mix. Your sound mixer will most likely pan the boom to the Left channel and the lav mic to the Right channel (or vice versa). You never want to leave it like this in post. You also never want to just pan both tracks to the center and leave both on. Amateur editors will make this mistake because they feel they’re getting a louder signal by having both channels on. In reality, they’re causing a terrible “phasey” sound as the waveforms of the two channels aren’t exactly aligned. They may not be completely out of phase but they’re almost never in phase either. That said, however, it’s ideal to have both present while recording. In general, the boom mic will almost always sound more natural and fuller, especially if you want to have the lav mic concealed under clothing. The lav mic may be the best choice when you’re in a noisier environment and the subject’s clothing hasn’t presented unwanted fabric noises. Also, if the subject shift’s positions dramatically or even stands up the lav mic will still be present. The camera may be able to follow the action where a boom mic on a stand is in a fixed position. For this reason, you’d favor the lav mic. If you’re doing several interviews with different people throughout the day you may notice that while the boom track sounds consistent regardless of who is being interviewed the lav mic varies in sound quality. This is mainly because different clothing fabric have different thicknesses, all of which play into how a concealed mic may sound. In general though, a professional production sound mixer will understand the best way to conceal the lav mic to optimize the sound regardless of clothing choice.

Beating on your chest. Another thing to look out for is when your interviewee is excessively tapping their chest to emphasize a point. This, of course, is a very natural action. However, if you are hoping to use the lav mic you’ll find that the audio file is going to have what sounds like a distorted drum on it every time there’s a tap. General rule of thumb is that if the subject matter isn’t sensitive or emotionally intense then it’s ok to remind the person not to do this. If they keep doing it then check in with your sound mixer to ensure that the boom track is clean and free of background noises. You’ll always get better results if you allow the person to be themselves. This just strengthens the notion that a quiet location is the key to everything.

Jewelry. Pretty simple really, if the person on camera is wearing jewelry that clangs, chimes, jingles, or makes any kind of noise it could possibly make your interview sound bad. Remember, if you can hear it with your own ears it will only be intensified through a mic.

The need for room tone:

What is room tone and why do you need it? Put simply, room tone is just a recording of the sound of the room during your interview. Its purpose is to provide your post team with audio content that is used to smooth out edit transitions. It can also be used to fill in small chunks of audio that need to be removed because of an unwanted noise in the background. Noise reduction software can use the room tone to create a noise profile that can be applied over the interview, which decreases the overall sound of the room without (ideally) negatively effecting the sound of the voice (when done correctly). Traditionally, room tone is gathered at the end of an interview for about 30 seconds. However, it is actually much more useful to grab shorter clips of room tone at the beginning, halfway point, and end of an interview. The sound of any given room changes over time, much like sunlight through a window will change your lighting set up over the span of a few hours.

When to allow background noise:

The show must go on, right? Sometimes things are beyond your control and you are forced to shoot in a non-ideal situation. You only have the subject for a short amount of time and can only shoot in his/her office….their staff is busy and refuses to quiet down, they won’t or don’t know how to turn off the HVAC….the office is cramped leaving little options for lighting and there’s a parked car outside whose alarm keeps going off in random yet frequent intervals. Yet, you have to get great sound for this interview. It’s the keystone of the story you’re telling…what do you do?

This frustrating scenario is a typical day for a production sound mixer. Apart from recording the highest quality audio that the location will allow, a lot of our job is to inform you of what noises to worry about and what noises to ignore while on set. It’s only the experienced production sound mixer that will really be able to gauge whether or not a particular background noise is a problem that can be “fixed in post.”

My work in both production and post-production audio provide great insight into how to communicate these variables to a director. Directors and field producers have enough to worry about and sound is often the last thing on your mind. That’s totally fine, that’s why you hire us. However, the information above is a great resource of items to consider prior to stepping on set for the big day.

Do's and Don'ts for Actors - A Sound Mixer's Perspective

If you’re new to acting then you may find yourself a little confused (or even possibly irritated) by how many “rules” there seem to be when interacting with sound mixers. There aren’t any actual rules per se. However, there are definitely some best practices that will ensure both your comfort levels throughout the day as well as great sound and the security of the sound mixer’s equipment. Here’s a few “dos” and “don’ts” for the emerging actor. 

First and foremost, the sound department’s role is one of customer service. We’re here to ensure that you sound great. From my perspective, the more comfortable you are on camera, the better you will sound.

DO: Wiring up an actor should be a clinical process. Your comfort and respect comes first. Your sound mixer should always first explain how they wish to wire you and then request consent. If you feel uncomfortable for any reason you have the right to request to be wired by wardrobe, HMU, or another crew member that you feel comfortable with. The sound mixer can walk them through the steps to ensure it’s done correctly. If your sound mixer scoffs at this then they are not a professional. The sound mixer’s only concern should be that 1) the microphone is placed in the position that sounds best,  2) that the transmitter pack is placed securely and comfortably, and 3) that the lav mic, wire, and transmitter are hidden well (when it’s applicable). 

DON’T: Don’t try to take the transmitter and/or mic off yourself when your scene wraps. Transmitter antennas, the lav wire, and the mic connectors are very sensitive and prone to breaking when not handled correctly. You never want to tug hard at a wire under your clothing because it could be taped elsewhere on your body. Excessive or aggressive pulling on the wire could result in breakage that is expensive to repair. These repairs cost anywhere from $60-$400 dollars per microphone.

DO: Inform your sound mixer if you prefer to wire yourself up. In many cases, you can do 50% of the job yourself. Personally, I always ask for the assistance of the person I’m wiring up. It not only makes my job easier but it usually makes the person feel more comfortable because a stranger isn’t getting in their personal space. Sound mixers carry a variety of mounts, transmitter straps, and adhesives to work with any wardrobe choice. For instance, there are specific lav mic mounts that are made for bras. When using this type of mount, it’s easier to have the actor thread the wire up under the shirt and under the bra, then to hook the mount to the center of the bra between the two cups. The goal is to have a woman’s cleavage create a buffer between the microphone and the clothing fabric. When the actor does this herself, it’s not only more convenient for everyone, it’s less invasive. 

DON’T: If you are wiring yourself up, don’t decide where to mount the microphone without discussing it with your sound mixer. The sound mixer should give you very specific instructions of how and where they want the microphone to be mounted. These instructions consider a number of variables such as what types of fabric you are wearing, what type of microphone is being used, whether or not you are indoors or outdoors, etc. 

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An assortment of mounts and adhesives that are typically used when wiring up an actor.

DO: Do inform your sound mixer if you are allergic to certain types of adhesives. We usually work with hypoallergenic material but there could be a scenario where we need to use a specific adhesive that could potentially cause skin irritation. Informing us of an allergy will help determine an alternative method. Also, in some scenarios we may wrap the transmitter pack in an unlubricated condom (which we call a “transmitter sheath”) to prevent sweat or moisture from getting in the transmitter. This is then usually placed inside a fabric waist, thigh, or ankle strap. However, if you have a sensitivity to latex it’s best to inform your sound mixer and they can make sure that the latex does not come in contact with your skin.

DON’T: Don’t move or take off adhesives yourself while on set. We place tape and other adhesives in very specific places to ensure that the mic is mounted properly and that the lav wire has enough slack to avoid pulling during normal body movement. If you are feeling uncomfortable, inform your sound mixer and they can make an adjustment. 

DO: Inform your sound mixer when you need privacy (going to the bathroom, leaving set to have a private phone call or meeting with the director, etc). We can turn your channel off remotely and make sure that your privacy is maintained. If you’re not in front of the camera, we don’t want to be hearing you through our headphones! Also, it’s often very easy to remove the transmitter pack while leaving the microphone securely attached. This way, there’s no chance of an expensive transmitter getting dropped into a toilet.

DON’T: Don’t try to unplug or turn off the transmitter. If your signal unexpectedly drops out your sound mixer may interpret this as frequency interference and scramble to make needless and time consuming adjustments. Also, some transmitters have their on/off or mute functions disabled unless a series of buttons are hit simultaneously. This is done to prevent accidentally turning the transmitter off during operation. 

DO: After you are wired, your sound mixer will ask you to check your levels. We don’t care what you say, we only want to hear how loud you are and what your voice sounds like under the specific lav mounting scenario. The best practice is to give us the volume level at which you will be speaking on camera. We will often ask a very generic question that is unlikely to be asked on camera. For instance, my go-to mic level question is “what did you eat for breakfast this morning?”.

DON’T: Don’t forget to inform your sound mixer if you are planning on making large dynamic changes during your performance. Of course, sometimes these are unplanned and we can deal with those instances. However, if you are planning to make a giant leap (like from whispers to screams) and it’s not scripted, simply tell your sound mixer so that they can make an adjustment to the settings to prevent distortion or clipping of your signal. Afterall, you don’t want your performance to end up unusable because the audio was bad!

DO: Do remember that once wired, you have a hot mic that’s usually (but certainly not always) located somewhere near your sternum. If you tend to tap your chest while talking you’ll also be tapping on a microphone, causing a loud thud that will render the dialog under that thump as unusable. 

DON’T: Don’t let the fact that you’re wearing a mic inhibit you from delivering the performance you feel you need to deliver. Your performance comes first. Your sound mixer will let the director or AD know if your actions are causing audio problems and make the necessary adjustments.

Deep Listening: A Production Sound Mixer’s Practice

In her groundbreaking work from 2005, Deep Listening, A Composer’s Sound Practice, Pauline Oliveros defines Deep Listening as “a practice that is intended to heighten and expand consciousness of sound in as many dimensions of awareness and attentional dynamics as humanly possible.” Her book outlines this practice as a form of sonic meditation to aid composers and sound artists in their work. Throughout its 100 pages are detailed exercises to help differentiate between focal attention vs. global attention and hearing vs. listening. However, this experiential meditative state of aural awareness is not limited to the trained composer. In fact, it’s something that we as production sound mixers employ on a daily basis.

Composer Pauline Oliveros 1932 - 2016 http://paulineoliveros.us

Production sound mixing for television and film is often viewed as a technical craft. The main responsibility of this job is to facilitate a director’s vision through recording and mixing the audio from on-screen sources. There are two key components to this role: record desired sound as clearly as possible, and eliminate undesirable sounds as thoroughly as possible. While filmmaking is generally regarded as a collaborative process, the contributions from a production sound mixer must be objective, easily discernible, and exist in a state of both present and future context. The present context concentrates on “does this sound good now?” while the future context worries about “will this sound good later during the editing stage?”. One would rationalize that the present context of a recorded sound dictates its future. However, the post-production process of editing audio for video or film into a finished work is done non-linearly from its original recorded context and thus subject to a number of complications unless careful considerations are made during the initial recording.  Here, Deep Listening is used as a tool to determine which aural variables need special consideration rather than as a meditative exercise to condition a holistic artistic practice.

There’s no such thing as a typical day at work in tv and film production. On any given day, I could be standing in a creek in the woods, in the basement of a homeless shelter, in the kitchen of a 5-star restaurant, or on a red carpet with famous actors. For the purposes of this argument though, let’s use an example of a sit-down interview at a home inside a city center. I will arrive about 15 minutes early to find parking, unload my equipment, and be standing at the door of our shooting location before the actual call time. My intention is two-fold. First, being punctual is simply essential to maintaining professionalism. Secondly, I want to have as much time as possible to understand the sonic landscape of the space in which I am to record sound. My goal is to create the quietest environment possible amidst the chaos around me. For any production sound mixer this is second nature. We turn off air conditioners, loud refrigerators, computers that have loud fans, fish tanks that have air circulators, and we will even convince a producer to pay off the landscaper next door so that we have a few hours without a leaf blower. Anything that makes noise must be dealt with to create a present context where the only recorded sound is the interviewee’s voice. If there is too much background noise the recording’s future context could be marred by tonal inconsistencies that are too noticeable in its new anachronistic edited state. An obvious yet frequent example is when a scene will feature the audio of a car passing by in one shot but no car in the following shot. While your brain processes a linear line of dialog you will subconsciously also notice something amiss. Our goal is to do our job so well that nobody notices we’ve done anything at all. Such is the nature of working with aural modalities in a visually dominated field. We are often overlooked and misunderstood. In fact, this reality is a caveat foreshadowing how difficult it is to do our job as film sets are anything but quiet leading up to when cameras actually role. How can you hear subtle hums and buzzes in a room’s tone when you’re surrounded by multiple people talking and various crew members doing their respective jobs. How can deep listening offset the normal and reasonable conditions of our work environment?  Audio specialists like production sound mixers don’t just hear sound, they are trained to listen to both a specific sound and the space around that sound simultaneously. We do this by constantly balancing between focal and global attention.

Keeping attention while on a film set

To keep focal attention is to simply focus in on a particular noise maker. As Oliveros suggests, it’s like zooming in and focusing a lens. For the subject of an interview the primary focal attention is on the overall volume, dynamic range, and tonal characteristics of the voice. The subject matter and content of what is being said is of no real importance in many cases. In fact, it’s often better to not focus too intently on the subject matter as it can distract you from listening to the audio quality of the recorded voice.  Secondary attention is then shifted to immediate distractions of the voice such as fabric noise rustling on a hidden microphone, jangling jewelry, a clock ticking in the background, etc. These immediate distractions are often easy to identify and reduce or remove. The more difficult aural elements are the ones that require global attention, developed over time through Deep Listening. Global attention, as Oliveros puts it, is “diffuse and continually expanding to take in the whole of space/time continuum of sound.” For the production sound mixer at work, global attention keeps us keenly aware of minute and incredibly subtle changes in background noises that could ultimately impede the editing process. When outside, this often manifests in listening to broad tonal shifts like the undulating tide of insects like cicadas and crickets or changes in the faint roar of distant traffic. When inside, like with our interview example, this global attention is often awarded to household mechanisms that can’t be turned off or even the mechanical fans from video production cameras. It’s not uncommon for our own tools to work against us sometimes.

A film set is seemingly the last place one would expect a crew member to practice a form of meditation. Yet, for the production sound mixer, it is, in a sense, a daily occurance. Given average circumstances for healthy individuals we all may be able to hear the sounds around us from a physiological standpoint, waveforms that enter our ears and travel into our auditory cortex to await processing. However, actual listening, which as Oliveros points out, is influenced by cultural history and life experience. Through the practice of patiently and deeply listening to our environments we can quickly identify a multitude of sonic variables that would otherwise be unnoticeable until a future context like the editing state. For this reason, employing practices from pioneers like Pauline Oliveros are vital to our profession.

The Art Of Being Silent

Silence, the great abyss. The infinite chasm of stillness that becomes deafening through patience… - An ancient Carbo proverb.

Let’s take a trip to a special place. A place where physics and consciousness intertwine to create a blissful state of aural euphoria. It’s a place we may never get to but our efforts toward this reticent destination paves the way for a strong foundation towards our common goal. That common goal is good sound on set.

As the acoustic ecologist Gordon Hempton once said, “Silence is not the absence of something but the presence of everything.” If you’ve ever tried to remain silent for 30 seconds for room tone you’ll likely relate to Hempton’s words. Silence can be incredibly hard for some individuals. Often, those that think they’re being silent are merely being quiet, or at least attempting to be. Yes, there’s a distinction between the two. The differences of which can have a major impact on how difficult of a job you’ll be giving to your dialog editor. What may seem like the faintest whisper to your colleague can end up ruining a great piece of dialog or alter what would have been an otherwise smooth edit. Sound is money people! It helps to imagine that our microphones are giant ears that listen, record, and save every single audible moment for posterity.

The human ear is a wonderful organ. It’s a complex machine of bones and hair cells that converts vibrations of air molecules into electrical signals that are sent to the brain, processed in the auditory cortex, and finally transformed from nerve impulses into intelligible symbols learned throughout life in order to navigate our way in the world. Our ears have an incredibly large dynamic range. The distance between the softest sound we can perceive and the loudest we can hear before damage is around 140db. Without getting into the math behind it, the decibel is a convenient way to abbreviate the measurement for changes in air pressure. The more scientific method for measuring sound would be to use Pascal, which involves a lot more numbers. For perspective, consider the average decibel level of common everyday sounds. (see chart below)

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Image courtesy of the American Academy of Audiology

The threshold for hearing in a young, healthy human is 0db (or 0.00002 Pa if you prefer Pascal). Breathing at a normal rate registers about 10 decibels, which is 10x greater than what is colloquially known as an absence of sound. On set, with some notable exceptions, we spend most of our time dealing with the “moderate” and “loud” volume areas in the graph. This is where the dialog between actors will be. This decibel zone is where us production sound mixers are transforming your art into digital 1’s and 0’s. Following the decibel’s logarithmic scale we find that the volume of our much coveted dialog sits at a whopping 1 million times greater than 0db.

Ever wonder where sounds you previously thought were silent stack up on the decibel level?

A vibrating cellphone sitting on a table about 3 feet from away will register about 51db. Shifting your weight while seated in a fabric chair (no metal or wood creaks) hits about 37db. Walking on a creaky wooden floor can be anywhere from 48db to 60db or higher depending on how a person walks.

This is all relative of course. The average “room tone” of an ideal location for a production shoot, practically speaking, is about 20db-30db in volume. That’s a room without HVAC bellowing from the ceiling of a corporate office building and no traffic outside seeping in though the windows. Ever been in a seemingly quiet room and your production sound mixer complains about a noisy hard drive fan that needs to be turned off or moved? Well, that’s because that hard drive fan can be as loud as 35-45db just in it’s resting state. The goal when choosing a shooting location is to find a space where the ambient sound level is drastically lower than the average level of a person speaking in a normal context. This creates what is referred to as a good SNR (signal-to-noise-ratio). When we have a good SNR we are able to edit the recorded spoken word with greater ease. There still may be some lingering broadband residual noise in the room but if it’s sufficiently lower than a normal speaking voice then it can be dealt with. If it’s necessary to use noise reduction software to remove some residual hum or ambient tone then the audio will benefit from our large dynamic range (aka large SNR) between the dialog and the noise floor. Noise reduction software makes educated, algorithmic guesses at what is desired sound and what is undesired sound. While it’s impractical for a room full of production professional to attempt to be literally silent, we should all strive to create the lowest possible noise floor.

In contrast to a normal setting, the ambience level of sound in Microsoft’s anechoic chamber, a room specifically designed to absorb all sound, was measured at a world record-breaking -20.6 decibels. It’s an almost unfathomable concept. A world without perceivable sound, yet there in the numbers lie proof that air molecules are vibrating. In fact, according to Richard Gray, that resting ambience level is “close to the limit of what should be possible to achieve without creating a vacuum – the noise produced by air molecules colliding with each other at room temperature is estimated to be about -24 decibels.” It’s been said that people who stay in Microsoft’s room for too long become disturbed and even sick as they begin to hear things like their own blood flowing through their bodies.

Back to our real world scenario for a brief exercise. We’re in a location for a production shoot, say an office building for an interview. I have turned off the HVAC and we’re far from a busy road. We’re shooting after normal business hours so the staff has left. The room is quiet but not uncomfortably silent. I have placed a supercardioid microphone above the interviewee’s head just out of frame. It has an internal self-noise of 12db, just a tiny bit above normal breathing. This noise won’t be heard in the room, only transmitted through the microphone into my recorder. It’s essentially inaudible relative to the much louder resting ambience of the room, which is sitting about 20x louder. Then, our subject speaks. Gloriously lush tone recreating every nuance of timbre pours through my headphones. Everything is going as planned. Yet several interview questions in something happens. A faint noise that no one deems audible is picked up, amplified through my signal flow and immortalized in digital binary code. A noise 100,000 times greater than what we call silence. It’s a director turning the pages of her notes, clocking in a deceptively loud 50db SPL. A sound so quietly loud that it will be heard simultaneously over AND under the dialog, despite the human voice being much louder. Under, as it’s obviously quieter. Yet over, as its unique timbre and frequency characteristics are different enough from the human voice that they stand out significantly when juxtaposed or overlapped.

The loudness of any given noise is relative. Relative to the individual and their own hearing but more fundamentally relative to its frequency and where the perceived pitch falls within our spectrum of hearing, which is 20Hz - 20kHz in a young, healthy person. Not all frequencies are created equally though (to our ears at least). For instance, our ears are more sensitive to “mid-range” sounds, falling between 1kHz-8kHz. This is an evolutionary trait often thought of as “fight or flight” sounds such as babies crying, twigs breaking, various animal sounds, etc. Lower pitch sounds require much more energy at our ear drums in order to be perceived as having an equal loudness to their mid-range counterpart. In fact, Equal Loudness is a scientific term to explain this contour in our hearing sensitivity. The graph to the right is an example of a Fletcher-Munson curve, which is one of many equal loudness contours to explain this phenomenon. The take away for this is that if you absolutely must make a sound on set, make it a very low frequency sound.

Now, back to our “offending” paper turning sound over the spoken word. This of course is a normal occurrence that is easily remedied with a simple polite explanation. No harm, no foul. However, it’s entirely possible that the paper turning has essentially ruined the audio for that particular take….and that may just be the take that you want for the final cut. What then?

So far, we’ve dealt with how loud a sound is perceived in the real world. What we’re really concerned with is how loud any given sound is after it’s recorded. Production sound mixers carry an arsenal of tools that help baffle offended noises (sound blankets) and reject the recording of sounds off camera (highly directional microphones). However, it’s often times impossible to not record a sound that is happening simultaneously to what you’re really after. Can it be “fixed in post”? Perhaps. Let’s take a look at some visual examples of the paper turning in question. Below is a spectrogram of an interviewee responding to a question. The director of this interview was 4.5 feet from the subject sitting just left of camera. The microphone for this interview was a Sennheiser MKH-50 Supercardioid boom mic placed roughly 9 inches from the subject’s mouth. A typical situation for a fairly tight picture frame. To the right of this image is the isolated sound of pages being turned.

The spectrogram graphs amplitude intensity from blue (quiet), black (literal silence) to orange. As you can see, the voice is significantly louder than the paper. However, it’s obvious that the page turns are noticeably audible, as indicated by the orange color on the spectrogram. The important take away here is to notice where on the frequency spectrum the offending noise lies. Notice how it overlaps with where the voice is?See that faint horizontal line running throughout the clip at around 19kHz? hat’s likely the buzz of a light or something coming through the AC electric. While it’s inaudible due to both it’s amplitude and it’s place near the end of the range of human hearing, it should still be removed. Luckily, a sound like that is easily eliminated.

There’s no part of the human voice that will be in this range in any kind of practical way. The next image shows the paper superimposed over the voice. Can you tell which is which from looking? I can’t. While it’s possible to remove specific transients of the offending noise, it’s virtually impossible to remove every bit of it. You could set EQ notches to remove the noise, which is in the upper mid-range. However, then you’d be left with a voice that sounds like it’s underneath a pile of blankets and coming from another room. Thus, unusable. You can set all the noise reduction plugins to their maximum intensity but then you’ll be left with a voice that’s riddled with digital artifacts and sounding like it’s underwater and recorded with a potato. It would seem like the only option then is to not make any noises!

This thought exercise is really just meant to aid in a mental framework where one considers every movement as an action that causes sound. Sound that may not be desirable in a recording. Although it’s impossible for a room full of production professionals to be truly silent while working, I still advocate that people approach this line of work with a degree of empathy. Not empathy towards how your sound mixer feels. Not empathy in any personalized sense that requires an emotional investment. I’m speaking about a degree of empathy towards the shared common goal of the work. Work that requires a commitment towards silence, however far from that goal we reach so that we can all reach that glorious land of aural euphoria. There’s probably some kind of zen-like proverb in here somewhere about the mindful intent being the act itself.

Why all this information? What use will this information provide? Put simply, I hope to give you a new perspective on how loud you are. Now shut up and let me record!

If a crew member makes a noise and there’s isn’t anyone around to hear it, will my microphones still pick it up?

Yes, yes they will.

- Gordon Hempton

- BBC article for Microsoft’s anechoic chamber

Why location sound mixers don’t have demo reels.

Every so often a potential new client will ask me to provide a demo reel. For those that don’t know, a demo reel is simply a collection of clips from previous productions one has recorded and mixed sound for.  It seems only logical that someone would want to hear evidence of my work prior to hiring me. Why then is it often viewed as a red flag within the sound mixer community?

In short, location sound recordists/mixers do not use demo reels because they do not properly portray the actual work that we do on set. In fact, using demo reels may actually mislead the viewer. Production work is a collaborative process and the audio of a finished piece has gone through several stages from pre-production to production to post-production prior to you viewing it. In many instances, each stage has had different sound professionals involved. When you watch a finished piece you are hearing production sound after it has been edited, ran through an assortment of plugins, and layered within a bed of sound design and music. Often times, the finished piece will actually sound much better than the production audio recorded on set. Through the post process, every lip smack and off camera thump is removed. Background noises are lowered or eliminated completely and dialog levels are consistent throughout despite how dynamic the speaker actually was in real life. When done properly, there is a cohesive flow to the diegetic tone that unconsciously holds the viewer’s attention while shots and visual perspective changes.  Why then wouldn’t we want to include this content on our reels?

Simply put, it’s inaccurate, technically untruthful, and leaves out so many other important aspects of our job. Moreover, we may not have access or even be legally allowed to share the content from a lot of our work.

I have several reels of my post production work. Most are demos of specific processes. They can be seen/heard HERE. With my post reels I’ve attempted to isolate methods, concepts, and unique styles that I was personally 100% responsible for. This can’t be done for production sound work. The notable exception of course is when the person recording sound on set was also the person responsible for the post production.

Below is a list of reasons why a professional sound mixer won’t have a demo reel.

• Many jobs require a Non-Disclosure Agreement stating that contents of the recorded audio with not be made public. A lot of the corporate work I do, for example,  are videos for internal communication.

• It’s difficult to get clips of work done on various shows because of copyright issues, and logistics of how involved you were on a shoot. Perhaps you only day-played on a local ‘bio-pack’ for a long running show. While your audio may sound incredible you are just a person who worked for a few days on something that has been around for years and you haven’t been able to establish the relationships necessary to get access to the finished content. Sometimes you can find a clip on Youtube a year or two later but you have no control over the quality of how that clip was uploaded.

• If you do find a show you worked on, it may be edited in such a way that your audio is interspersed with the work from another sound mixer that may not be as good. Do you then include that content with a disclaimer? This would only cause more confusion.

• It’s possible that all of your audio was replaced with ADR not because of quality but because of an editorial choice from a director based on an actor’s performance. More likely, ADR may have been required because the shoot required loud generators to be running while over your otherwise perfect audio.  

• Finally and most importantly, production sound reels don’t take into account all the other variables of our work. A reel can’t showcase learned skills like quick troubleshooting, professionalism when micing talent, respectfully negotiating with store owners or location managers to turn off noisey appliances or HVAC systems, and most importantly, keeping cool under pressure.

A more accurate way to gauge a sound mixer’s experience is to simply request a list of credits and get personal referrals from industry colleagues you trust. Roughly 80% of my work comes from either personal referrals or recurring clients. As I mentioned earlier, it’s completely logical to request proof of someone’s ability to do a job. However, with location sound mixers, you’ll never find that proof in a demo reel.

Full disclosure, while I don’t have a sound reel for production work I do actually keep a running playlist on Youtube of random clips from shows I’ve worked on, which I update once a year. I’ll only provide this playlist if asked and only after a disclaimer at why it’s misleading. My rationale is that while reels don’t make sense, we are in fact in a customer service industry and I want to do anything in my power to attract new clients.