How to Remove Low-end Noise from Sound Effects for Video
The audio side of video is often not well recorded due to small production budgets and short time frames. Therefore, during post-production, producers can be assaulted by a series of previous sonic missteps. An annoying rumble or hum in the low end is a common problem in audio recorded for video.
Software plugins that remove noise from audio abound and some function very well. However, under a fast approaching deadline, one may not have the time to find, purchase, and learn the nuances of a new plugin. For these situations, simply turn to the default equalization and reverbs provided in your audio or video editing software.
Use standard package plugins and the following tips to eradicate nasty noise from the bottom end of your audio recordings:
First, use a Single Band EQ to try and cut out the offensive hum. This type of EQ will cut out all sound below or above a certain frequency. For example, since low rumbles generally occur around 60 Hz, you can use a Single Band EQ to cut out everything below 80 Hz which will remove the hum without adversely affecting the dialog.
Next, target a very small width of the offending sound spectrum by using a Parametric EQ and “notching,” which decreases a certain frequency and its octaves such as 80 Hz, 160 Hz, and 320 Hz. One preserves the surrounding audio by being able to target a small area of audio.
Third, use a Parametric EQ to boost the desired audio slightly. By doing so, it will be prominent over the noise and take the listeners attention away from the unwanted hum. For example, boost a bit at 5 Khz to raise the human voice over a low hum.
Finally, one can use reverb on the entire mix once the lower rumble has been cut out. This can reduce the “tin can” effect that might result from minimizing the lower end.
Following the above strategies may not completely erase all problems associated with bad audio, but they can improve the quality of the product when unwanted noise and dialog are competing for attention in the mix.
