When I first began field recording, I captured any sound I could point my microphone at. It didn’t matter what it was. A shrieking kettle? Sure. Light switches? Done. Traffic from my balcony? I have dozens of tracks.
Beginning field recording is an exciting time. It introduces a way of thinking about the world that surrounds us once again, this time through sound. Recording these foundation sound effects around us is an important step on a field recordist’s journey. It introduces them to gear, how simple sounds interact with equipment, and something even more important: an appreciation for the nature of sound itself.
There is one drawback, however: these initial recordings may not be your best. It’s understandable, though. You’re still learning, after all. So, these tracks may have sloppy technique, jumble subjects together, or feature the recordist’s movement more than the target itself. Are these sound effects useless?
Not at all. Why? Well, they help new field recordists learn. And, with a bit of work, their value can be reclaimed. Software can rescue clips damaged from distorted peaks and from being smothered by a blanket of noise. Today’s post takes a look at software designed to do exactly that: Accusonus’ compelling ERA audio restoration suite.
Please note: I am very detailed. This article will take you about fifteen minutes to read. Click the button below to email the post to read later.
Rescuing Sound Effects
I captured thousands of foundation sound effects when I first began recording back in the days of DAT recorders, around 1997. For the most part, these have remained tucked away in a seldom-accessed folder on my sound library hard drive. From time to time I revisit them. As software options have grown and de-noising technology has advanced, I’ve found I’ve been able to reclaim some of them. Gems can be found fixing clips from one’s back catalog.
It’s not easy work. Getting decent results from legacy recordings captured during the “tape era” requires digging deep into software settings. Every imaginable option can be tweaked to reveal pristine recordings. Honestly, though, it’s a tedious task.
I recall trying to strip the noise from old kitchen drawer recordings. I’d scavenge for the smallest fraction of noise to create a de-noising template, then audition my repair efforts over and over, leaning in towards the screen to hear if changing my threshold settings from 8 to 12 improved anything. It’s a maddening grind. As you can imagine, I didn’t return to editing those sound effects often.
This has changed, though. Why? Well, recently I was approached by the people at Accusonus. They kindly offered I take their ERA Bundle 3 for a spin to help fix damaged field recordings, and asked if I would like to share my experience with readers. I was intrigued by the software’s approach to fixing noise. So, I agreed, with the provision that a post would be transparent and brutally honest.
No problem, they said, “that’s how we learn.”
Established in Greece in 2013 and now run jointly in America as well, Accusonus began by releasing music-focused software before moving onto dedicated noise repair plug-ins. ERA-D was revealed in 2015. Since then, their suite of tools has grown. The ERA family of software now includes:
- ERA De-Clipper.
- ERA Noise Remover.
- ERA Voice Leveler.
- ERA Reverb Remover.
- ERA De-Esser.
- ERA Plosive Remover.
The ERA Bundle 3 Pro ($399) includes all of the plug-ins, while the ERA Bundle 3 Standard ($149) omits ERA-D (detailed joint noise and reverb removal) for a price savings. Each of the modules can be purchased separately for $59, with the more sophisticated ERA-D ringing up at $299. Each is available as 64-bit AU, VST, and AAX for Mac, with VST and AAX formats available for 64-bit Windows machines. Two week demos are offered if you’d like to test before buying.
The Accusonus Approach
Accusonus’s ERA line differentiates itself from other noise-removal software with a novel approach: each of their ERA plug-ins is designed around a single, large knob. The concept? Just a twist of a knob is all that’s required to repair audio.
Now, other sound restoration plug-ins have tried a simple approach. Antares SoundSoap is one of them. Some of iZotope RX’s plug-ins are less convoluted than others. However, a simple de-noising interface is refreshing to those used to dragging rows of sliders or twisting banks of knobs. Many pros want results quickly and simply. For instance, video editors don’t want to dive deeply into settings that will take them away from their work. Any sound pro would love reclaim hours lost to tinkering with plug-in settings. No podcaster wants to waste time navigating a intimidating wall of intricate app options. So, the concept has appeal.
It’s normal to wonder, though: is it possible to reduce reverb, strip noise, or restore peaks with what is essentially a single parameter? After all, every damaged file differs. Noise may invade some frequencies more than others. Clipped audio may squash a peak to a greater degree than the the ones beside it. And what about removing reverb? It’s difficult to separate a sound effect’s natural ring-off from the reverb in the space around it.
So, is it possible to get good results from the ERA bundle’s single-knob approach? Let’s learn.
Three Restoration Plug-Ins
You’ll notice many of the ERA plug-ins are designed to salvage bad dialogue. Most of us here are field recording or sound design fans. So, I’ll focus on looking at three plug-ins that help repair sound effects:
- ERA Noise Remover.
- ERA Reverb Remover.
- ERA De-Clipper.
Let’s see how each of the plug-ins perform. For every one I’ll introduce the plug-in, describe the restoration problem, and explain how each plug-in intends to fix it. Afterwards, I’ll share the original sound paired with various processing results so we can learn how it sounds when we push the software lightly or aggressively.
A quick note before we begin: we’re adapting these plug-ins for field recording use. Most of the time, noise restoration software is designed to work on music and dialogue. Sound effects are quite different, of course. Let’s bear this in mind while reviewing the results.
ERA Noise Remover
Designed to reduce hum and hiss, the ERA Noise Remover plug-in targets fluorescent light buzz, preamp hiss, HVAC noise, and more. Its main dial controls the processing intensity percentage.
Some tweaking is possible: buttons at the base of the plug-in specify which frequencies will be targeted. The plug-in has typical output, A/B selection, and on/off options.
What to Listen For
Getting good results when de-noising isn’t easy. The reason is that noise is broadband. It soaks every frequency with hiss. That means removing the noise may take some of the good audio, too. In an ideal world, the noise will be removed and the principle audio will remain. That rarely happens.
De-noising can also introduce problems. Strong settings may remove noise but leave robotic- or slurred-sounding artifacts behind. In general, noise removal works best with consistent sounds. Recordings with loud transients are more difficult. The noise will appear to diminish more slowly after sharp hits, and seem to “pump.”
Let’s see how the ERA Noise Remover works.
Noisy Sound FX
For my de-noising tests I decided to revisit my older field recordings. Digging through my archive, I found a mix of clips that needed cleaning: wind chimes, clink tracks, cars, winds, and more. Noisy clips are some of the hardest tracks to repair. A cross-section of short clips and longer ambiences would reveal just how the Accusonus software performs.
Removing noise is challenging. The ERA plug-in certainly makes it simpler. Using the Noise Remover, an editor doesn’t need to hunt and peck in the spaces between sounds to find a noise template to remove hiss. Instead, the plug-in just removes hiss on its own. This is a major improvement I enjoyed.
What about the sounds themselves? For this plug-ins and the ones that followed, I chose a selection of arbitrary settings of 20, 40, 60, and 80 percent to see the intensity of the effect.
The first was a bartender clink track I recorded to DAT many years ago. If noise removal software will have a weakness, it will be by removing too much high end, making the clips sound unnaturally muted. So, the clink track had a good range of bright sounds to test.
In the original you can hear the room hiss and some HVAC. At all settings the noise is removed pretty cleanly without any artifacts or displeasing pumping. The 60 percent setting pushes it a bit far, and I wouldn’t recommend choosing that, but it’s interesting to hear.
Even more challenging? Wind chimes. To be honest, I didn’t expect much from this file. The combination of strong noise and high-end tones would be hard for any noise removal app.
And indeed it was, you can hear how the brightness is sacrificed, and the repair hugs a bit too tightly to the sound. That’s not really a slight towards Accusonus, the plug-in wasn’t designed for sound effects like this, but it is important to note.
Another specific sound effect revealed an interesting quirk about the plug-in. You can hear in this DVD drawer opening that the noise reduction gently fades away after the principle sound effect ends. I assume this is done to work more fluidly with dialogue noise removal. After speaking with Accusonus, they told me this “adaptation time” will be tweaked in the next version.
Looking at the spectrograph shows more info about how the plug-in works. It seems to apply a frequency cut as well as broadband de-noising.
The final clip was most successful. At 20 and 40 percent settings, the plug-in did a great job of removing noise from a key being slid into a car ignition.
Note that the short sound wouldn’t have allowed for finding a noise profile manually, as done in competing apps. That wasn’t needed with the Noise Remover. A major benefit.
ERA Reverb Remover
The ERA Reverb Remover plug-in was created to help isolate dialogue and make spacious musical performances feel more present. Field recording fans will find it helpful, too. How?
Discovered your sound effects have too many reflections? Perhaps you smashed rocks in a quarry and the reverb has more character than the stones themselves. Maybe you want to reduce the reverb on that stairwell door you captured. While not specifically designed for sound fx, the Reverb Remover plug-in can help.
The plug-in’s controls are similar to the Noise Remover plug-in: the main knob controls the processing percentage, buttons target frequencies, and supplementary options round out enabling the plug-in, A/B selection, and output. There is also an “auto” slider which automatically attenuates the output, if you prefer.
What to Listen For
Without care, it’s possible de-reverb plug-ins will strip the actual sound along with the echo. Conservative settings may leave too much of the reverb in the recording, making the sound have a roomy feel shortly after the crest but dropping off immediately after. And, of course, pushing software too aggressively will damage the recording by adding artifacts.
Stripping Reverb from Sound Clips
A few years ago I recorded some very loud sounds. The first session captured fighter jets performing at an air show. A bit earlier that summer I recorded howitzers firing a military salute. I was happy with the recordings, however, I wanted to experiment with one part of their character.
As fighter jets screamed across the sky, the ripping sound echoed off the tall condos at the Toronto waterfront. In the same way, the howitzers were gathered in Queen’s Park and their blasts echoed off sandstone buildings surrounding the area. While the natural echo of these recordings were pleasant, it did limit how they could be used. Perhaps a sound designer would use a jet fly by to build a powerful logo whoosh. Maybe the howitzer blasts would be used on an empty battlefield instead of amongst skyscrapers. In either case, the reflections I recorded would sound out of place. Let’s see if we can create an alternative version less “live” than the original. I also decided to fix a mix of echoey doors.
I was eager to try the Reverb Remover on the fighter jets and howitzers.
I found that 40 percent didn’t have a convincing difference to the howitzer’s urban echo. At 60 percent, the drop off was quite sharp, and at 80 the difference was distracting.
The fighter jet had a long approach and departure. I had wondered if the Reverb Remover would have any effect on removing the building reflections.
No such luck. At 40 percent I didn’t perceive a significant difference, and at 60 percent it damaged the file. Clearly not the best choice of sound for the software.
I had much better luck with reverberant doors: a clothes dryer door, a metal door, and a clothes washer door.
The increase in processing removed the echoes fairly smoothly; a 40 percent setting removed a bit and still sounded fine, while 60 and 80 percent settings removed it completely without sounding unpleasant (the metal door at 80 percent being an exception).
Examining the spectrogram was interesting. The software appears to keep the high end over 8 kHz, and works by removing reverb on everything lower than that.
No matter how carefully a recordist sets their levels, it’s always possible for surprising, loud sounds to distort. Production mixers are most familiar with this: a sudden shout may peak in an otherwise typical conversation. This problem isn’t isolated to recordings on set, though. A traffic recording may become distorted as a fast truck passes. The clatter of boxcars may be blasted by the sound of a trailing locomotive. Particularly loud sounds such as fighter jets will overwhelm recordings even when levels are set low.
The ERA De-Clipper (currently in beta) was designed to assist. Instead of a single knob, the plug-in has four buttons. Choose the Type 1 button for typical problems, and Type 2 for more challenging issues. Select high (more processing power required) or standard quality. A clipping indicator at the upper right reveals when problems occur. There’s also a “Protection Indicator” to the left, which is a clever way of discovering if your work is still too hot for your editing app – if so, just reduce the output slider. The plug-in has the same A/B and on/off toggle switches as others, too.
What to Listen For
When repairing clipped audio it’s important to listen for pumping. De-clipping may reduce the peak, but the audio before or after may be too loud or soft, creating a distracting sense of attenuation. Also, when de-clipping is pushed too far it may actually introduce crackling, so we will need to be mindful of that, too.
Distorted Sound Clips
I’ve always been a fan of car racing. A few years ago I found a countryside racing strip and recorded dragsters tearing down the track. Many different racing classes performed that day, each with their own engine specs and power. It was difficult to know which class was racing next. So, levels set for the quieter vehicles where often followed by the roaring Top Fuel speedsters. The result? A few initial louder car passes distorted before levels were adjusted. Could they be fixed? I experimented on those, as well as a handful of other short clipped tracks from my sound library archive.
The de-clipper is designed to deal with short clips of music or dialogue. I threw some challenging recordings at the plug-in to see how it would perform.
The first was a thunder burst with background rain. It was recorded on an old Zoom H4. The crack was extremely distorted. Both standard and high settings reclaimed the blast. To my ears, the high setting sounds more fluid, and the standard seems a bit more coarse.
The next was a horn honk. It appeared to fix this simply and well.
I tried the dragsters next. The first pass was extremely distorted and sounds like mush. The difference between the standard and high processing seemed similar, with the high having a smoother and softer feel.
The next dragster file was a burnout. You’ll notice the image shifting a bit. This is because the cars fishtail in place while warming up their tires. Keep this in mind when listening to the results. The high setting appeared to do more accurate work fixing the waveform. In general both were a lot better. One interesting thing, both of the repaired files dropped a few decibels at about four seconds after a tire chirp. I’m not sure what why De-Clipper did this. Perhaps because it is a sustained sound, while the plug-in was designed for shorter clips?
The final test file was a CF-18 fighter jet passing by. Now, fighter jets naturally sound crackly. However, if you look at the waveform, you can see the pass by is damaged. Let’s see if we can repair it.
The standard setting lowered the level, however the waveform remained severed. The high setting repaired it. While it indeed reclaimed the of the distortion, it appeared to compress the sound around the peak. The effect was that instead of the peak swelling higher as you would expect, it simply remained at the same level. The effect was slight, and it did sound pleasing just the same, though.
Using the ERA Bundle for Sound FX Work
So, how did the ERA plug-ins perform?
I found the Noise Remover plug-in got good results with little work – provided you choose the right sound files. Complex sounds or those with high end with long, ringing tails may appear muffled or reveal noise attenuation, and are best avoided. That’s fine, though. They’re clearly not the target for the plug-in. Perhaps the biggest benefit is the plug-in’s simplicity. I’ve spent months of my life hunting for noise profiles. Given the proper sound effect, the plug-in can sidestep this onerous task and produce clean, smooth audio.
Following the same theme, the Reverb Remover performed best when used on short, sharp, and clear sound fx. It excelled on reverberant doors, and I especially liked how a span of settings removed reverb to an equally pleasing degree. Want just a bit of echo removed but still retain a hint of room? No problem. Want that booming door slam completely dry? The Reverb Remover can do that, too.
The De-Clipper worked best on similar files. Simple sounds like the horn honk were repaired effortlessly. More complex sounds such as the fighter jet worked well with a few tweaks.
The upshot? While working in the field, recordists need to adapt to their surroundings: weather, traffic, crowds, and more. In the same way, often field recordists have to use tools designed for other professions: videographers, podcasters, video editors, and others. The ERA bundle excels when removing noise from dialogue and music. Used on the proper material, its “one-knob” approach finds a place with field recordists and designers, too. It’s able salvage tracks which cannot be recorded again simply and effortlessly so pros can escape the edit suite sooner and return to the outdoors.
Overall, I was impressed with the ERA restoration plug-ins. What was particularly notable was that the software rarely produced artifacts. Instead, the worst that happened was that it squeezed a sound too much. That’s a natural expectation of turning settings up to “11”, and fits with the Accusonus approach: just turn one knob back and results will improve. It’s a simple and elegant way to approach audio restoration, where results are not determined by panels of switches and toggles, but by your craft and your ear.
- View the Accusonus plug-ins.
- Browse the plug-in manuals.
- Read an Accusonus guide for repairing audio.
Accusonus ERA Bundle Giveaway
Accusonus is kindly giving away a free copy of the ERA bundle. I’ll share more details about this next week. Sign up for the free newsletter to learn more, or watch for the post on Twitter or Facebook.