Tutorial: 9 Tips to Improve Editing and Mastering Sound Effects

Field recording good audio is only one of three steps to creating a great sound effect. The full process includes:

recording a sound effect with microphones
mastering the sound fx in editing software
describing and categorizing the completed sound

At Airborne Sound we demand excellence in each of these steps. Today I’ll write about the second step, mastering.

Mastering music is much different than working with sound effects. It requires different skills. I won’t discuss that today. We’ll focus on sound effects.

What is mastering sound effects?

Mastering sound effects, broadly speaking, has two approaches:

cleaning up problems introduced while recording
enhancing or changing an existing sound (this may blur the line with sound design)

Mastering sound effects is a nuanced skill. The approach to mastering a sound effect depends on the sound itself. A mastering technician will apply different skills to fighter jet sound fx than to patio crowds clips. A filter or plug in may work with one sound but be inappropriate with another. It’s similar to the idea that you don’t use a wrench to hammer a nail. The proper mastering technique depends on the sound itself.

Broadly speaking, however, common tasks when mastering include:

editing, trimming and applying fades to a sound effect
modifying the level or loudness of a sound
removing audio imperfections or sounds that distract
applying filters and equilization to remove unwanted parts of a sound, or highlight some aspects over others
enhancing the sound with processing and plug-ins to give the it new characteristics

As you can see, mastering sound effects is a complex task.

At Airborne Sound we have created guidelines for our team to ensure each sound clip is mastered with the highest quality.

Here are our tips to improve mastering sound effects.

Check your work
This is the number one skill that separates pros from the amateurs in any profession. Check your work before you deliver.

Wait a day before you listen to your mastered work again. You will have fresh ears. Play back the audio and you’ll spot editing errors quickly, such as:
- bad edits (hiccups or bad crossfades)
- dead air at the head or tail of sounds
- bad fades (sound does not ramp up or fade out smoothly)
- bad loops

Remove the recordist
Remove any presence of the recordist from the track. Common errors: breathing, clothing moves, slight foot shifts.

Smart fades
Fades allow a sound effect to begin and end smoothly. The problem is that the audio in the fade itself is unusuable.

Airborne once reviewed a sound submission of a crowd clip that had a 30 second fade out. This was, unfortunately, useless. Why? Everything after the first second cannot be used it is only partially audible. The following 29 seconds were wasted.

Each sound will require its own appropriate fade length. A good starting place is a 1/2 second fade in, and 3/4 second fade out. Use your ears and create a fade that feels natural.

Also, choose a good point to begin the fade: not in the middle of a yell or a bell toll, for example. Begin the fade where the sound effect takes a breath.

Volume
Sounds that are -15 dbFS or lower should be normalized before they are used; they’re just too quiet to be useful in most situations.

Save the editor work. No one wants to receive a quiet sound that they will need to normalize before they can use it.

Use your judgement to choose the right gain range. Some suggestions:
- standard specifics: no lower than -10 dbFS
- close crowds, traffic or bird atmospheres: -7 to -10 dbFS
- quiet ambiences such as wind or room tones: -12 to -15 dbFS
The exact level can be a matter of preference. However, the important point is that very quiet sounds are not useful. Increase the volume to an appropriate level.

And for that matter, there’s no need to blast every sound you cut. Not every sound works well at maximum level. A soft breeze shouldn’t be as loud as a gunshot.

Note: if there is too much noise floor after you’ve raised the level, erase the file.

Remove performances
Remove all music from your recordings. Broadcast music (TV, radio, shopping mall PA) or buskers and street performers, whether close or distant, are copyrighted. Using a sound effect with music in it could get you sued. Don’t tempt the RIAA.

Avoid this and you’ll also respect the original artists who created the performance.

Also questionable: video games, Windows or Mac OS X sounds, cell phone ring tones. All are copyrighted.

Remove image shift
Sometimes the recordist turns the microphone, or it wobbles. The result is that the sound seems to waver.

This is difficult to detect unless you are listening sharply. It must be removed so that the sound’s perspective will be consistent.

Watch your multimeter

A multimeter is a tool that shows information about the sound effect. Most multimeters will include:
- a spectrum analyzer
- stereo image analyzer
- level meter
The stereo image analyzer will help you spot problems with phase and image width. The spectrum analyzer can display exactly which frequency is causing that persistent whine. The level meter will show sound levels with far more accuracy than a default audio editor will allow.

A multimeter will help you edit smarter and quicker.

Metric Halo’s Spectrafoo and RND’s Inspector XL are examples of multimeters.

Beware denoising

It’s rare when a sound effect is recorded perfectly. Often problems such as clicks, pops, hum, rumbles and hiss can be introduced.

Software like iZotope RX is excellent for removing these things. Waves Z-Noise is also good.

Be aware that learning to use these tools correctly takes time and trial and error.

Don’t rush with these tools. If they are used carelessly they can cripple your sound effect even more.

Improper use of a declicker may leave thumps behind. Pushing a denoiser too far will result in artifacts that sound chirpy and watery, or like “singing robots.”

Be conscious of this. Plug ins are not a cure-all for a bad recording.

Which leads us to the final tip…

When in doubt…
…throw it out. Not sure if a sound is worthwhile, or valuable? Heavily edited? Erase it.

Poor or even mediocre sound files will not help your projects, or make your library more valuable. Great sounds make you want to cut. Poor sounds will bore you, and your clients.

At Airborne Sound we keep only exciting, vibrant and high-qualty sound effects. Keep only these sounds in your collection to inspire your recording, editing and sound design.

Delete everything else. Your library and your projects will be better for it.