Fixing hum problems with processing
Video: Fixing hum problems with processingWe're now going to take a look at some noise problems you might encounter when you're editing your dialogue tracks. Continuous tonal noise problems, like a refrigerator, or a machine based hum, are common but sometimes, the easiest type of noise to fix. In this movie, we're going to look at removing a hum from a scene using an equalizer plugin. On dialogue track three in this scene, Mr Dalton is sitting at his desk. There is no dialogue here, but we'd like to preserve the sounds of his movements.
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In this course, explore a powerful round-trip workflow between Logic Pro and Final Cut Pro that helps sound editors to quickly mix dialogue, sound effects, and music for film. Author Scott Hirsch frames the lessons in a way that appeals to filmmakers of all levels, as well as professional and amateur audio mixers. He starts with exporting your tracks from Final Cut Pro and taking advantage of the film and video templates in Logic Pro, which makes project setup a snap. Then discover how to consolidate and edit dialog, fix noise problems and background hum, and add special effects. Finally, explore how to use automation and EQ to enhance and match your final tracks to the picture.
- Setting up your project
- Exporting audio and video
- Editing dialogue
- Fixing hum and broadband noise issues with processing
- Synchronizing sound effects
- Automating volume
- Printing the final mix stems
Fixing hum problems with processing
We're now going to take a look at some noise problems you might encounter when you're editing your dialogue tracks. Continuous tonal noise problems, like a refrigerator, or a machine based hum, are common but sometimes, the easiest type of noise to fix. In this movie, we're going to look at removing a hum from a scene using an equalizer plugin. On dialogue track three in this scene, Mr Dalton is sitting at his desk. There is no dialogue here, but we'd like to preserve the sounds of his movements.
Unfortunately, there's a rather annoying hum that makes the scene kind of hard to watch. (SOUND) Luckily, we can use an equalizer to notch out the offending frequency and save the day. We'll use the Logic Channel EQ as a real time plugin. With track three selected, click in your Insert Column on the track in the Inspector on the left and locate the Channel EQ.
This is a real-time plugin, so we can move the controls and we'll hear instant results. First, we need to locate the audio frequency at which the hum is active. Click set locators to set a playback area around the regions. Next, let's go the second set of settings on the EQ and turn the gain up all the way. This is one of the four bell shaped or parametric bands on this multiband EQ.
Next change the q value to the highest until you get a nice narrow band. Now is the fun part, while playing the clip start sweeping the freqency setting until you hear the hum get louder. Let's try this. (SOUND) Now as you can hear, it got louder around 120 hertz.
We could even type in 120 in this field to be more precise. Great, now that we've found the offending hum we can simply pull the EQ gain down all the way to minus 24DB. One other thing we want to do in the channel EQ is to engage the high pass filter, that's the one on the far left here. This cuts out any low frequencies and allows all high frequencies to pass. If we set this control to around 75 hertz, that'll be good at removing any low frequencies we don't want in this scene in addition to the hum we've already removed at 120 hertz.
Let's take a listen after we've done this. Now as you can hear the hum has been removed and we were able to salvage this clip. But we're not done quite yet. Remember, this is a real time plugin and we don't want this to effect every clip on this track for the whole movie. So let's actually render the effect to this clip. With the regions still selected, right click on one of them and choose bounce in place.
The bounce regions in place dialogue will appear, now, we can name them Dolton EQ. We have to put it on a new track for now, and let us leave the original source regions muted. We will leave all the other settings, click OK to perform the bounds. There we go, we have a new track with the rendered regions in there. We can keep the old ones or we can just drag these regions up there and delete the track and don't forget to remove the EQ setting on the real-time EQ. Clicking here just to choose no plug-in.
Now you've got some rendered regions with our EQ that remove the hum. You can use this kind of eq processing to avoid any continuos hum like sound on clips you encounter in the future.
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