The different kinds of treatment structures
Much like the professional recording environment, for the at-home recording artist, three specific structures have been identified as the most effective, easy to construct, and cost-effective to implement.
Gobo:
A gobo (which stands for, “go-between”) is a free-standing, sound absorbent barrier commonly used in professional recording environments to reduce the amount of low-frequency information captured from a source.
Isolation booth:
Isolations booths are physical enclosures intended to remove or lessen the sonic character of an untreated space so that the recorded signal contains a minimal amount of any undesired noise.
Reflection guard:
Much like an isolation booth, the intention of a reflection guard is to mitigate the amount of room noise capture in an audio signal, while maintaining some of the inherent character of a recording space.
What treatments work best for specific instrument types
While each of these acoustic treatments can be used in a variety of different ways, there are certain structures that work best depending on the source attempting to be captured.
Acoustic Instruments
Recommended treatment:
- Isolation Booth (primary) – We found that in completely isolating these types of instruments the recording yielded the clearest results, allowing for the best possible post-production.
- Standing Gobo (alternate) – While not as effective as isolation booth, a standing gobo can offer a significant reduction in room noise, as well as a very noticeable improvement to controlling low-end frequencies
Amplified Instruments
Recommended treatment:
- Isolation Booth (primary) – For louder sources, such as an amplified guitar, completely controlling the environment is critical to achieving the best overall sound. Ideally, a walk-in closet or similar enclosed space is most effective, however, a constructed isolation booth will also work.
- Standing Gobo (alternate) – Excellent for mitigating room noise and reflection when recording amplified strings. Room sound is preserved while reducing white noise and undesired signals. Additionally, combining a gobo with a constructed isolation booth yields positive results when a physically isolated space is not available.
Bass or other Low-frequency Instruments
Recommended treatment:
- Standing Gobo (primary) – For low-frequency instruments we found that a standing gobo allows for control of the low-end while not “burying” the upper-mid range of these instruments character, yielding a clear and accurate representation.
- IMPORTANT NOTE – Beware, complete isolation of these instruments is not desired. It will remove too much of the low-end information, making the sound feel choked and muffled.
Drum and Percussion Instruments
Recommended treatment:
- Drum Gobo (primary) – In recording acoustic drums, the main goal is to isolate the direct mics (i.e. kick and snare) while allowing the overhead microphones to capture the stereo image of the complete drum set while reducing any desired drum resonance that can bleed into the overhead microphones.
- IMPORTANT NOTE – Kick and tom isolation from the overhead microphones is key to achieving a clear drum image. Additionally, having the side wall blankets positioned as high as possible without resting on the cymbals themselves is recommended.
Individual Vocals
Recommended treatment:
- Isolation Booth (primary) – In vocal production, completely isolating the source and microphone is the highest priority. White noise and room reflections bleeding into the vocal track add difficulty to post-production effects. The purpose of the isolation booth is to give the mixing engineer the most amount of control over these two factors.
- Reflection guard (alternate) – Similarly to the isolation booth, the reflection guard aids in reducing white noise and room reflections. While not as effective as an isolation booth, a reflection guard is an excellent alternative if the sonic character of the recording space is already desirable and requires minimal treatment.
Understanding these basic treatment guidelines is helpful. However, it is important to note that all rooms have an individual acoustic signature and some experimentation is encouraged on behalf of the performing artist to find what will work best in their specific environment.