Navigating the sea of audio recording for interviews can seem daunting at first glance. Still, with an understanding of the fundamental principles, you can transform your production values from amateur to professional. This article will guide you through the various aspects of capturing excellent interview audio, from understanding microphones and their patterns, to audio setup, to post-production.
Microphone Basics and Polar Patterns
A microphone’s ‘polar pattern’ describes how it picks up sound from various directions. Here are the common patterns you should know:
- Omni: These microphones pick up sound from all directions equally.
- Cardioid: These microphones capture sound primarily from the front, with moderate side rejection and a small sensitivity bubble at the back.
- Super cardioid: These have a narrower front pick-up than the cardioid, with a higher side rejection and a moderate sensitivity bubble at the back.
- Hyper cardioid: These mics have an even narrower front pick-up pattern than the super cardioid, with larger side rejection and sensitivity bubble at the back.
- Shotgun: These have a super narrow front, smaller sensitivity bubbles on the sides, and the back. These are best for side rejection.
Other factors that affect a microphone’s performance include:
- Proximity Effect: The closer you get to the mic, the higher the bass response. Beyond 8-14 inches away from the source, the proximity effect is reduced.
- On Axis / Off Axis: This refers to how a microphone is directed towards a sound source. To capture all frequencies accurately, especially the higher ones, the microphone must be pointed directly at the source.
Microphone Types and Considerations
Shotgun microphones are long-barreled microphones with narrow acceptance patterns. The longer the barrel, the narrower the pattern. They are excellent at rejecting side noises due to their super-cardioid or hyper-cardioid nature. These mics have higher sensitivity, leading to a higher output. Be aware that very high sensitivity can distort loud signals.
When selecting a shotgun mic, look for ones with low self-noise, high sensitivity, and XLR connections. Mics powered by phantom power tend to have lower self-noise and better sensitivity compared to battery-powered ones.
Dynamic microphones are reliable and cost-effective with decent off-axis sound rejection. They do have a lower sensitivity compared to condenser mics, and proximity effect can be significant depending on the polar pattern.
Condenser microphones are known for their high sensitivity and accurate audio records, thanks to their lightweight diaphragms. However, they’re less resistant to shocks and temperature/humidity changes. ‘Pencil condensers’ are great for interviews due to their small size and super cardioid patterns.
Lavalier mics are small and perfect for hands-free operation. They can be clipped onto the subject’s clothing, ensuring a good signal-to-noise ratio because of their proximity to the source. However, hiding these mics can reduce the frequency response. Always make sure the positioning is comfortable and visually pleasing, while avoiding areas that might lead to noise interference.
While convenient, budget wireless systems can be less reliable than their wired counterparts. It’s usually best to stick with wired systems unless wireless ones are necessary.
Setting Up Your Mics and Recording Audio
Ideally, you want to use a dual system audio set-up, separate from your camera. Your audio recorder should feature XLR inputs, phantom power, clean preamps, and headphone monitoring. High-sensitivity mics or a mixer can help you pick up signals more cleanly.
For monitoring your audio, opt for closed, over-the-ear headphones or noise-isolation inner earphones with a flat frequency response.
When setting up mics, aim for an 8-inch distance from the mouth. If using wired lav mics, ensure you make a small loop at the attachment point to relieve stress from the mic if the cord gets pulled.
Post-Production: Making Your Interview Sound Great
After the recording, you’ll need to sync the audio files with your video. Programs like Adobe Premiere Pro have features that make syncing audio and video a breeze.
Once you’ve synced and linked your audio and video clips, right-click on the audio to adjust the audio gain. Normalizing your audio to -3dB can help maintain a consistent level.
In post-production, there are several methods to clean up your audio and handle room noise, including EQ adjustments, compression, and the use of expanders.
Finally, if you’re mixing your interview with background music, strive for balance. Listen to your mixes at both quiet and loud levels, and ensure the voice stands out clearly over the music, especially in the 2kHz to 3kHz range.
All in all, understanding your tools and adhering to these guidelines will undoubtedly enhance your audio recording skills for interviews. With some practice and patience, you’ll be on your way to delivering high-quality, professional interview recordings.