from training.npr.org: https://training.npr.org/audio/mixing-diy/
How to mix: 8 steps to master the art of mixing audio stories
Podcast mixing — in fact, mixing audio stories of any kind — can be tedious. It’s the part of the production process where you create balance, consistency, and clarity with all of the audio elements in your story. But for many, it’s the least understood and most overlooked part.
This step-by-step guide outlines a straightforward way to mix podcasts and audio stories. As you explore the process, you can play along:
Download these example audio files to try out the methods in your own audio production software. To use these files, import them into your audio editor and align each file to the top of the session (0:00). The audio is already organized for you.
For a more detailed look at mixing, as well as a list of the tools you’ll need, check out The producer’s handbook to mixing audio stories. And if you’re new to this, check out these posts:
- Brush up on audio terminology: ‘Butt cut what?’ A glossary of production terms
- Learn to recognize bad audio: The ear training guide for audio producers
- Improve audio use: Put your audio to the test: Know when to use it or lose it
Eight steps to the perfect mix:
Follow this order every time for an efficient workflow.
Step 1: Organize
The first step in mixing is to organize your mixing session. The goal is to create a project that looks organized, is properly labeled and has similar audio grouped on individual tracks.
1. Arrange your tracks in this order:
- Host/reporter audio
- Actualities and guest audio
- Ambience and room tone
- Master track
This is a common layout in audio storytelling, whether it’s a 20-minute longform podcast or a 45-second news spot. Using the same layout for every project makes it easier to navigate and collaborate with others. As we’ll see later on, it will also make it easier to set levels, EQ and compression.
2. Organize the audio clips:
Skim through your clips and ensure that each track includes only clips that are alike. Each clip on an actuality track should be from the same person and interview, each clip on an ambience track should be from the same scene, and so on. If it’s a different voice or scene, it gets its own track.
You may have to make more than the five original tracks to accommodate all your clips. Name them appropriately and avoid generic titles like “Track 1” or “Audio 1”. Instead, use descriptive names like “Larry,” “Jerry ISDN” or “AMBI market.”
3. Cascade the tracks:
Once you have named the tracks and grouped together similar clips, organize them visually so that they cascade diagonally from top-to-bottom, left-to-right. If the “Sara phoner” actuality is heard in the story before “Tracie ISDN,” then the “Sara phoner” track should be above the “Tracie ISDN” track. Cascading clips like this will make the project much easier to navigate and mix.
When the organization is done, it will look like this:
Or, for a larger session, like this:
A little time invested in this step at the beginning of the project will make the rest of the process go quicker.
Step 2: Rough in levels
Take a moment to adjust the level of your tracks so that every voice track is roughly at the same level. We are about to assess whether any voices need fixing with equalization (commonly called EQ) and compression. To do that, all of the voices need to be at a similar level, because our brains generally perceive louder sounds as “better.”
If your organization has a standard level it uses for mixes, use that as your target. If you don’t know what it is, stop now and go find out! Many production organizations have a standard target that everyone uses for mixing, and that helps things sound consistent from one piece to another. Most productions use loudness meters when mixing for broadcast or podcast.
Don’t try to get things perfect at this point, and spend only a minute or two on this step. It’s ok for transitions and fades to be rough.
From here, we are going to deal with tracks one-by-one, in isolation. You can use the solo button to do this.
A brief note about solo and mute buttons: They achieve similar outcomes and have very different purposes. Solo is intended to temporarily isolate the selected track and quiet all of the other tracks with one button press. Mute is intended to quiet only the selected track. Use the solo button for its intended purpose, not like an “on” button — it can interrupt routing and change the way your audio editor behaves.
Step 3: Determine if you need to EQ
Now we’re going to check whether any of the tracks has a tonal issue that can be improved with equalization. If you’d like to know more about EQ, check out The producer’s handbook to mixing audio stories.
1. Solo one track and listen
Solo the first track and play it back. Do you hear any unnatural tonal issues like rumble, hollowness, harshness, or sibilance? Are any frequencies jumping out at you?
2. Find and fix the tonal problem
If so, insert an EQ plug-in on the track and follow the steps outlined in The producer’s handbook to mixing audio stories to find and reduce the problem frequencies. It’s a good idea to preemptively use a high-pass filter to clean up useless low-end rumble. You may also need to hunt for and reduce a tonal problem.
3. Repeat for each track
A note about ambience: Often we record ambience that matches up with voices recorded in the same location, both need to match in tone. So if you adjusted the tone of a voice track with EQ, apply the same change to the accompanying ambience track. Additionally, if there is an environmental issue like rumble or hum in the voice track, it’s likely audible in the ambience recording. You can fix it with the same EQ settings.
Remember: A plug-in will process every clip of audio on a track. This is why you organize similar clips from the very beginning.
When you are happy with the results, keep the track soloed and move on to the compression step.
Step 4: Determine if you need compression
If you’d like to know more detail about using a compressor, check out The producer’s handbook to mixing audio stories.
1. Assess the presence of the voice
Ask yourself these questions:
- Does the person speak in an even and consistent way?
- Does the speaker sound strong and present?
- If you turn the listening level down halfway, can you still hear and understand every word?
If you answered “yes” to all the above, you can probably get by without compression.
But if the speaker emphasizes certain syllables and words in ways that make them sound inconsistent or “jumpy” in level, you might need it. Consider using compression if a voice doesn’t sound strong or if it is layered over music.
2. Add a compressor if you need it
Insert a compression plug-in on the track and follow the method to configure it outlined in The producer’s handbook to mixing audio stories.
3. Repeat for each track
A note about ambience: You don’t usually need to apply compression to ambience. However, compression can impact the level of voices. If you used compression on a voice track, you may need to adjust the level of the accompanying ambience to match.
Step 5: Check edits and fades
1. Listen to each edit
2. Check for fades on each clip
Make sure the tops and tails (beginnings and ends) of each clip have fades, even if they are very short. It’s best practice to place fades at the top and tail of every clip to avoid abrupt entrances. You might not hear an issue now, but it could pop up later in a different listening environment.
This process is easier if you know some of the keyboard shortcuts for your audio editor. Learn the shortcut to jump to the next edit on the track as well as the shortcut to move the playhead back a few seconds. With those two shortcuts, you’ll be able to jump from edit-to-edit, back up a couple of seconds and audition the edit relatively quickly. If you don’t know those shortcuts, stop right now and go learn them!
Step 6: Fine-tune levels
Fine-tuning levels is called “balancing.” Each audio clip needs to match the clip preceding it — not too loud, not too soft. Ambience and music should be audible, but not compete.
To create this balance, you have to have a foundation. We’ll use the host/reporter track for that purpose.
In Step 1, you organized the tracks in this order:
- Host/reporter tracks
- Actualities and guest audio
- Ambience and room tone
- Master track
This is the order in which you should balance.
Instead of trying to mix all of the tracks at the same time, use the host/reporter track to create a foundation with which to balance all of the other tracks. Your goal is to balance the clips on the host/reporter track to each other and get them close to the mixing target. Then you’ll create the rest of the mix by comparing the balance of the other clips and tracks to the host/reporter track (we’ll call it the “host track” from here).
To sum it up: Mix each track from the top down.
1. Balance each clip on the first track to the target level
To start this step, mute all the tracks except for the host track. Listen through the first clip of audio. Does it regularly hit the target on your meter and sound consistent to your ear? You quickly roughed in levels in one of the first steps, so the level should be close — but it might need adjusting.
If a sentence or a phrase seems out of balance, apply the level automation tools in your audio editor to that portion. Try to make changes in sentences or phrases.
Once the host track consistently hits the mixing target on your meter and each clip sounds balanced to the clip that precedes it, you are ready to move on to the next track.
2. Balance clips on the next track to the first track
Turn off the mute so you now hear the first actuality/guest track and the host track together. Listen to the last few seconds of the host clip going in to the first actuality clip. Do the two sound balanced? Make the appropriate change to bring the actuality in line with the host track. Now listen through the rest of the clip and determine if a change is necessary. Finally, check the transition out of the clip into the host track to ensure it is balanced.
Repeat this process for all of your guest tracks, un-muting and adjusting one new track at a time.Once you’ve balanced each clip to the host track, do another pass and listen to all of the transitions. Use this opportunity to double-check balances and make note of transitions and edits that will need to be masked with ambience.
Step 7: Balance ambience and music
This is a tricky step! The ambience and music should not compete with the voice tracks, nor should they be so low that it’s not audible when listening in a car or noisy environment.
To judge the level of ambience and music, use the “rock and roll” mixing trick. Also, listen to your mix on headphones and speakers — the balance is going to sound a bit different on each. A compromise between the two options will work well in most situations.
This is also a good time to check the fades on ambience and music.
Note: Often, the waveform of music clips looks quite different from voices. Music production involves lots of compression that makes the waveform look small. It will likely sound louder than it looks.
Step 8: Listen to the mix
Listen to the entire mix, top to tail, on headphones. Listen for anything unnatural, and pay close attention to transitions and balances of voice over ambience or music.
That’s it! You created a well-balanced mix in an organized and efficient way. The first couple times you do it this way, it might take a long time. But don’t worry. It will get easier the more you do it.
You can print out a 1-page checklist below:
Rob Byers is the director of broadcast and media operations at Minnesota Public Radio | American Public Media. His audio engineering there contributed to a Peabody Award and Pulitzer Prize. As part of the NPR Training team, Rob worked with public media producers across the country. He has written other production guides, including The Ear Training Guide for Audio Producers and The Audio Producer’s Guide to Loudness. He mixes the Radiotopia podcast Criminal.