The Advantages of Recording with Proximity
One of the most underutilized tools for clean recordings is the simple use of proximity, or bringing the microphone closer to the desired sound source. It’s common to see content online and on broadcast television microphones several feet away from the person speaking. Try recording sound from greater than 12″ (.3 m) away in an apartment, office space, outdoors, or performance venue and the results will range dramatically from mediocre to poor. There are several main culprits that interfere with any recording, and they can be vastly reduced just by just moving closer to the mic.
Let’s say that you’re recording a solo voiceover. If you record in a home or office, there’s a strong likelihood of something in your environment making unwanted noise. The noise may stem from a computer fan, a fluorescent light, cars passing by outside, or a ticking clock. It’s only when you place a microphone in the room and turn up the gain that all of the ambient sounds in the environment become apparent. No microphone or software can fully correct for this, so there’s no cure for background noise once the audio has been recorded.
Moving closer to the microphone doesn’t eliminate background noise, but changes the relative balance between the undesired sounds in the ambient environment and the desired sound. Recording from a distance is like using an oversized net that picks up the desired sound but captures a myriad of unwanted sounds along with it.
Keeping with the earlier example of the voiceover, moving closer to the mic makes the recorded voice comparatively much louder than the ambient environment. The greater the separation between the desired sound and undesired sound, the greater the isolation and cleaner the recording. Using this method, anyone can create a clean, professional sounding voiceover in almost any environment.
Acoustical Reflections / Reverberation
Another downside to recording from a distance is the introduction of acoustical reflections, or room reverberation entering the microphone. As sound waves are generated from any sound source, the sound radiates outward in 360 degrees until it hits an object in its path. All objects absorb sound at certain frequencies while reflecting sound at others. The shape of a room can amplify some frequencies more than others, creating unbalanced reverberation with amplitude spikes some frequencies and nulls in others. Where room reverberation might sound natural to the human ear, it often sounds muddy or honky on a microphone. Worse yet, reverberation can interfere with vocal clarity and intelligibility.
Recording more closely to the microphone changes the ratio of direct sound entering the microphone relative to the acoustical reflections. There’s nothing better than an acoustically treated studio, but moving closer to the microphone in an easy way to reduce room acoustics in any environment. If you desire reverberant sound, try adding a reverb effect it in a DAW in postproduction where you’ll have a wider range of effects and a greater degree of control. See our post for optimizing sound for reverb for more information.
Bass and The Proximity Effect
With the exception of a few specialty microphones, directional microphones are more sensitive to bass when placed closer to the sound source. Some recording engineers dislike this, but the proximity effect adds a rich, full sound the recording that can be changed later if needed. You can easily attenuate low-end using an equalizer (EQ) in a mixer, DAW, or video editing application. It’s better to record up close with a full, bass-heavy sound rather risk recording an overly thin sound with less ability to correct it in postproduction.
When to Avoid Isolation
Microphones don’t always sound best within eight inches of the sound source, and there are times when moving it further away improves the overall sound quality. We only recommend recording at a distance when recording in a controlled, studio environment, or when recording an instrument with a large reverberant surface area. When it comes to music recording, instruments like pianos, guitars, and even violins have large surface areas that resonate and contribute to the sound of the instrument. Place a microphone too close to a guitar, for example, and you’ll end up with an unrealistic, localized sound of the instrument. A guitar sound hole might sound boomy up close, but 3′ (1m) away might sound more balanced with the sound of attack of the strings and resonance from the guitar body. Unlike most home or project studios, professional studios and sound stages are typically built with heavy, acoustical insulation to isolate it outside noises. Likewise, most studios walls are lined with acoustical absorption material, like fiberglass panels, that minimize or contour room reverberation. It can be advantageous to record from a distance in true studio environments.
Recording from a distance also becomes necessary when you cannot physically move the microphone closer to the source, such as when recording on camera talent without a lavaliere. In these cases, use dedicated shotgun microphones, like the Audio-Technica AT875 or Sennheiser MKH-416, and place the microphone as close to the edge of the camera frame as possible. The 2012 film, Les Miserables became famous for capturing all of its music from the on-screen performances, as opposed to the more common Hollywood technique of recording and synching vocals in postproduction. The audio engineers coordinated closely with the director and camera crew to stay as close to the performers as possible without placing the microphone inside of the camera frame. Doing so helped to isolate the vocals from extraneous noise and provide the cleanest audio feed from the performers.
Microphone placement should be done strategically, using the best position to suit the needs of the situation. For almost every instance of recording in a non-studio environment, the closer the better. There are no easier or more effective ways to reduce unwanted sounds, reduce acoustical reflections, or to add a full-sounding, tones to an audio recording.
It’s worth experimenting with recording from different distances to determine its degree of effectiveness. With a portable recorder or DAW, try recording your voice from a distance of three feet (one meter) with an average recording level of -20dBFS. Afterward, place your lips within five inches of the microphone, and decrease the gain and record with an average level of -20dBFS. Listen back and compare the differences, paying attention to the amount of ambient noise and room reverberation in the recordings. The test with the microphone closer should contain a more “present” and bass-heavy recording, albeit with much less environmental noise. Experiment with projecting more loudly through the microphone to create even more separation from the background environment.
Photo credit: Eryk Thompson