Sound Perspectives 101
Sound. It’s the most elusive element that seems to plague filmmakers so very often. We commonly hear filmmakers saying things like, “sound is 2/3 film” or “sound will make or break a production.” The list goes on. Yes, we have been able to get that “picture” quality to a “pseudo” Hollywood look, but sound is difficult. Or is it?
Sound is generally an afterthought for most filmmakers. Most people assume that sound is something you get audio engineers, sound designers, editors or mixers to look after.
In part, this is because film doesn’t have the capacity to record sound and audiotape can’t capture images. 35mm & 16mm film doesn’t capture audio, but the impact of digital camcorders changed all that.
Today, filmmaking is literally becoming more affordable, scaled down, budget conscious and more accessible. Hence what follows are several people’s attempt to do everything themselves without adequate training, knowledge or information.
Until recently, film and sound were separate “departments.” Now with the advent of independent filmmaking, these two elements are now equally important.
Over two years ago, in a video titled Advanced Sound for DSLRs, Steve Weiss of Zacuto asked a very legitimate question, “Why is sound always the bastard child to video people?” What ensued was a very informative and educational 13 minute supplement. Here, I will attempt to provide a simple yet comprehensive guide to sound recording for picture.
In the next series of articles, I will attempt to dispel any fallacies or misconceptions regarding sound recording for film, simplify some basic fundamentals, which is paramount to getting great sound for all your projects, large or small, and most importantly, make it an easy, fun and enjoyable process.
Various topics will include:
1) Microphone fundamentals: selection, placement, application and audio comparisons.
2) Recording devices and mediums. Equipment selection. AB test.
3) Capturing sound on location and studio controlled environments.
4) Processing and editing sound in post, including ADR, foley, sync, etc.
5) What is that “Hollywood” sound?
With plenty more to come…..
As a tertiary educator, I often get the following questions, just to name a few:
1) What is the best equipment to use for general location recording?
2) What is the best software for sound editing?
3) What types of mics are best for different scenarios?
I will also cover filmmaking fundamentals such as the importance of basic cinematography, camera types, formats, shot composition, headroom, lighting techniques and dynamic range. Audio also has many other important questions that precede the ones above.
While I don’t expect aspiring filmmakers to open an entirely “new can of worms,” understanding audio fundamentals first will improve your productions immensely without going to audio school. Therefore, the following questions should include:
1) What is sound and how does it travel and behave?
2) What are acoustics and how do they affect recording in pre and post?
3) What is signal flow, headroom, and dynamic range?
4) Audio structure in both the digital and analog domain
5) 3 Basic building blocks of sound manipulation and processing
6) Proximity effect (i.e., microphones, speakers)
7) Sample rates and bit depths
The list goes on, however, I will make references to the fundamentals in the applications.
OK. Let’s start with observations in digital fundamentals. In the audio industry, there was a time when analog tape was the coveted means of professional audio capture in sound recording. To some extent, it still is, though subjective. However, this method is expensive and cumbersome. Enter hard disk based formats and solid-state drives, we can now record, edit and mix sound without breaking the bank balance.
Much like film stock compares to audiotape, today picture can be recorded to a digital storage medium. So now audio can be recorded to very small, portable and affordable devices. A 16mm Bolex camera and a Nagra reel-to-reel audio tape recorder may have epitomized the concept of portability in the 1960’s, but now the HDSLR and the Zoom H4N have revolutionized filmmaking in the 21st century.
Is it hard to comprehend audio in theory? Not if you look at the similarities between digital filmmaking and digital audio. In this first article, I want to bring your attention to these terms. In later articles, we will go into more detail.
Where the term “blown out” is utilized in analog photography, clipping in digital photography occurs when incorrect exposure causes image highlights to lose detail and ultimately be rendered useless.
Clipping in digital audio is similar when levels are set too high during the input stage. Digital distortion occurs and renders the audio unusable because sonic fidelity and detail are lost.
Clipping in audio can also occur at the pre-amp stage, mic stage and analog to conversion stage. Hence it’s not just a simple adjustment of exposure when comparing to image capture. We will look at these problems in later articles.
In film, this generally refers to the horizontal resolution of an image, its size and its ability to contain as much information as possible. Hence relative pixel dimension comparisons and common digital cinema formats include 720p, 1080p, 2k and 4k.
Resolution in digital audio similarly refers to the ability of capturing audio at higher resolutions (sample rates) 44.1k, 48k, 96k and 192k, being the most common. This aspect is commonly misunderstood in digital video editing as well as an area where most mistakes occur when synching audio with visual. Further explanation will be given in an article devoted to this topic.
Compression is used in digital cinema to manage large amounts of data. Due to limitations in human visual perception, compression is utilized to remove redundant information from a signal. Where prosumer cameras use higher compression ratios, high-end cameras generally use lower ones or none at all.
Compression in audio and video are similar in terms of data management. Both utilize Lossy & Lossless compression, which again removes redundant information in our ability to hear lower or higher frequencies.
Using inferior compressed audio formats such as mp3, meant for consumer use, usually results in less than desirable results.
Compression in audio is also used to normalize audio to make fluctuating levels in speech or signals sound more coherent and consistent.
In film, dynamic range refers to the darkest point within which a camera can capture to the lightest. Where darker images might sometimes contain more “noise,” highlights can also clip.
In audio, dynamic range refers to a similar principle of recording audio within an optimum latitude range that goes from inaudibility to distortion. Recording a sound too low and playing back at an audible level will introduce extraneous noise, raising the noise floor and therefore increasing the signal to noise ratio.
When recording a sound too loud in analogue, tape saturation occurs and compression kicks in which gives the audio’s dynamic range a bit more latitude. However, in digital audio, clipping occurs and you end up with digital distortion.
Conclusion for now:
I won’t carry on with the endless comparisons. One can clearly see the similarities between audio and visual theory.
I would like to leave you with a thought though. While we spend good money on cameras, what do we really expect when we only spend a fraction of that cost on very little equipment coupled with limited knowledge on sound?
When I was embarking on completing my masters of audio design at university, we were required to conduct research on hardware components versus audio software generated algorithms. In the audio world, we call this ABX testing and much to my amazement, the results were negligible and miniscule. As I have always stipulated, you pay for what you get. So again, while people are willing to part with a few thousand dollars on a camera, why would they only spend a couple of hundred bucks on a small consumer type field recorder? That being said, it all comes down to the individual behind the instrument. With proper information and knowledge, you’ll be able to determine what constitutes great sound, irrespective of price. Rest assured, the folks at Zacuto are committed to education. Stay tuned for more articles on sound.