Important Aspects of Recording
When recording sound, there are multiple precautions and measures that must be put in place to achieve high quality audio, as well as many things to be aware of. These include:
- Room Tone, Atmosphere and Reverb
- Headroom and distortion
- Directionality and mic placement
In this post I will discuss the issues of each of these and how I have tackled them.
Room Tone, Atmosphere and Reverb
Room tone is the sound that can be heard always from outside and is typically unobtrusive to a recording. Atmosphere is the presence of sound within a room or the location that the sound is being recorded in that may contribute to a certain effect or background to a recording.
The use of room tone is to avoid harsh differences between silences and sound playing over a clip. Therefore, for my “WALL-E” project I did decide to record some room tone in order to blend the different sound clips seamlessly together and disguise any changes from silence to sound. I feel as though this has allowed my project to be a lot cleaner, polished and more professional.
On the contrary to this, the dialogue recording interview task was one singular long sound recording with no breaks and silences in between, so this was not necessary.
In regards to atmosphere noise in my recordings, I wanted this to be eliminated completely so that I could have completely clean audio clips with no background noise to work with in post-production. This meant that certain equipment was used throughout the recording process, as well as aiming to record in particular environments to avoid these issues.
For the sound dubbing task, I did avoid any outside environments where necessary. This eliminated the possibility of wind sounds as well as distant cars being featured on the recordings. Recording most of the sounds inside allowed the environment to be much more isolated, allowing me to capture the sounds more clearly with less to no background noise. Secondly, I did use a boom pole with the shot gun mic, usually balanced on the foot instead of the floor to act as a barrier to any low frequency rumbles coming through the ground from a nearby road. The elimination of these frequencies is important as they may effect the fidelity and quality of a recording if not removed.
Reverberation refers to when sound waves are reflected off different surfaces in the environment of recording. These consist of early and late reflections, both which are affected by how many parallel boundaries there are in a room, as well as any use of acoustic panelling or materials in the room that may absorb different frequencies.
For the interview, we did use a set up within a studio space that also contained some acoustic panelling on the walls and large carpeted areas. The use of this environment meant that reverberation was reduced as the acoustic panels created a more even distribution of sound waves. Also the density of the carpet was responsible for absorbing certain frequencies and therefore created a cleaner and clearer sound within the recording.
Headroom and Distortion
When measuring the amplitude of sound in digital form, it is often measured in dBFS (decibels relative to a full scale) where 0 on the dBFS scale would be equal to an amplitude of 1. Therefore, anything that is measured above 0dbFS is likely to become distorted, meaning the sound quality lacks and fidelity is lost (fidelity referring to whether the sound is true to its original source).
To tackle this issue, a technique called “headroom” is used when recording sound. This is done by ensuring that the gain is at such a level that the sound does not peak anywhere above -6dBFS. This allows literal headroom above the maximum peaking point in case of any small mistakes in recording and also allows some room for post-editing such as filters and many more of which may affect the level afterwards.
Therefore, in both my overdubbing project and dialogue recording I ensured that the levels when recording stayed around the -12dBFS mark, also not allowing them to exceed -6dBFS in order to prevent distortion. This made my recordings much cleaner as there is no compromise to the quality, and also meant there is less of a need for editing large amounts of volume in the post-production phase as all of the clips are of a similar volume.
Directionality
When recording sounds in different environments, it is important to take into account the directionality of different microphones. This means which areas around it a microphone will pick up sound from, which is called a polar pattern. For example, a common polar pattern seen in a variety of microphones is the cardioid polar pattern. This creates a shape around the microphone similar to a heart, showing that sound will be picked up mainly from the front region as well as slightly around the sides.
The microphone I chose to use for both of my projects is the Sennheiser ME66 shot gun microphone. This has a hypercardioid microphone, which is the most directional kind of polar pattern. Almost all of the sound captured is from the front area of the microphone, with a small amount coming from just behind. Due to this, I took extra care when positioning the microphone during recording in order to capture the most consistent and clear sound.
For example, when recording the chair scraping across a kitchen floor for the sound dubbing assignment, I followed the chair with the microphone whilst maintaining the same distance throughout and avoided deviating from the original position. This allowed me to capture consistent audio that did not contain massive fluctuations of volume as the microphone was the same distance from the sound source throughout the entire recording.
In the interview recording, we positioned the microphones directly at the nose and mouth area and reduced our movement whilst filming in order to capture the voices clearly and prevent any fluctuations in volume. We also ensured to keep the microphones out of shot on the camera whilst being positioned correctly towards the people in the interview.
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