One of the most powerful sound-shaping tools in Soundtrack Pro is Match EQ. This plug-in can be used to analyze an audio file, compare the tonal data with another audio file, and then generate a frequency spectrum so that the second file matches the frequency characteristics of the first. This is an ideal tool to make dialog tracks from different location or ADR sessions sonically match one another.
Match EQ uses a virtually unlimited number of filters (it uses as many as it needs in any particular instance) to accurately generate a tonal spectrum to achieve a match.
The Match EQ interface
The Match EQ GUI (graphical user interface) offers a detailed frequency spectrum display where you can monitor the spectral content of the audio being analyzed and processed.
The buttons below the spectrum display let you control the audio analysis and spectrum application. The Learn button under Template allows you to analyze an audio file (or clip) that you want other files to match. The Learn button under Current Material allows you to analyze a second audio file—one that you want to modify to match the first. The Match button under Current Material will compare both learned frequency spectra, generate an EQ curve, and apply it to the second audio file so that it matches the first.
Here's a look at two basic workflows where you might want to use Match EQ.
Using Match EQ in a Multitrack Project
Let's say that you're working on a simple voice-over project, as shown in the image below:
You have three dialog clips that feature the same voice talent. However, let's say that the middle clip shown is a retake that you recorded at a later time. Maybe this clip was recorded in a different room, or with a different microphone, or perhaps the narrator simply sounded different that day. For whatever reason, the middle clip sounds noticeably different than the first and third clips. Match EQ can correct this quite easily. Here's how.
- Insert Match EQ in the track; in the Media and Effects window, click the Effects tab.
- In the Category pane, select Soundtrack Pro and in the Effect pane, select Match EQ. (Tip: Instead of scrolling down the Effect list, just click on any listed effect and press the M key; Match EQ will immediately be highlighted.)
- Click the plus sign (+) button to insert the plug-in on the track.
- Click the Advanced button to open the Match EQ interface.
- To make the middle (second) clip sound like the others, you want Match EQ to learn the frequency spectrum of the original recording session (the first or third clip) and apply that spectrum to the middle clip to make it match. Set the playhead to just before the first clip.
- Play a bit of the clip to listen. Click the Learn button under Template to start analyzing it and then stop playback. The button and the dB (decibel) scale indicators on each side of the spectrum display turn red. The spectrum display shows the frequency content of the clip.
- Click the Learn button again to stop analyzing.
- To analyze the middle clip, set the playhead to just before the second clip in the track. Play a few seconds, then click the Learn button under Current Material to start analyzing it. The button and the dB scale indicators turn green. The spectrum display shows its frequency content.
- Match EQ now "knows" the frequency spectra of both recording sessions. To have it create an EQ curve that will correct the middle clip to match the others, click the Match button. The button and the dB scale indicators turn gold. The spectrum display shows a graphic representation of the EQ curve being applied.
- During playback, apply the EQ curve to the middle clip only—you'll need to bypass the curve while the first and third clips are playing by automating the "match" parameter. To do this, go to the Timeline in the Project window and choose Latch from the automation mode pop-up menu. This allows Soundtrack Pro to write automation during playback.
- In the Media and Effects window, click the Match EQ disclosure triangle to display the controls for its parameters.
- Note the Auto column, which contains checkboxes, on the right side of the window. These checkboxes allow you to enable automation for their respective parameters. Select the Auto checkbox next to Match to enable it.
- Set the Match parameter to "Off" for now (click the Off radio button), since we don't want to apply the Match curve to the first clip.
- Start playback and when the playhead reaches the gap between the first and second clip, click the Match parameter's On radio button in the Media and Effects window.
- When the second clip finishes playing, click the Match parameter's Off radio button again.
- Stop playback, then rewind.
- Choose Play from the automation pop-up menu and then play back the track. The EQ should engage just before the second clip starts to play and then disengage just after it's finished.
- If you click the Dialog Track's disclosure triangle, you can view the details for the track, which will look something like this:
Using Match EQ in an Audio File Project
In some workflows, you may prefer to apply Match EQ directly to an audio file, rather than automating it within a track. To do this:
- Open the clip that you wish to process as an Audio File Project by double-clicking the file.
- A dialog appears, asking whether you wish to edit the file destructively or non-destructively. Select the option you prefer, then click OK to open the Audio Wave Editor.
- Create an action layer using Match EQ by choosing Process > Effects > EQ and Filter > Match EQ.
- The Match EQ interface appears. In this example workflow, we want to "teach" Match EQ the frequency spectrum from another audio file by loading it. Control-click (or right-click) the Learn button under Template.
- From the shortcut menu, choose Generate Template Spectrum from Audio File.
- In the resulting dialog, navigate to and select the audio file to which you'd like to match the current file.
- Match EQ analyzes the selected file.
- To analyze your current audio file, click the Learn button under Current Material, then click the Play button at the bottom of the interface.
- After a few seconds, stop playback to stop the analysis.
- Click the Match button to have Match EQ generate an EQ curve that will match your current audio to your audio template.
- Click the Apply button to create an action layer that comprises the Match EQ effect.
For a detailed description of Match EQ and most of the other effects included with Soundtrack Pro, see the Logic Pro Plug-in Reference PDF file.