How to Record Fireworks Sound Effects
Next week we are releasing a new firecrackers and fireworks sound effects library. Today’s article will have a first look at the sound effects to give a preview of the what you can expect in next week’s release.
Want to learn how to record your own fireworks sounds? The post will also describe how our field recordists planned, recorded, mastered, and curated the sound effects.
Why Record a Fireworks Sound Effects Library?
The original fireworks sound effects were recorded a few years ago before the pandemic. At that time, I had returned to Canada after travelling abroad for 2 years. I would be there for a few months before travelling again. I wanted to record all I could before I got back on a plane.
In Canada, it’s not possible to buy or use fireworks except during specific celebratory days. As luck would have it, Canada Day was one of those days, and was only a few weeks away.
There are many “fireworks display” sound libraries available. Also known as pyrotechnic shows or fireworks shows, these libraries feature field recordings of many fireworks going off over 20-30 minutes to celebrate holidays like the 4th of July, Bastille Day, Guy Fawkes Night, and others. Those fireworks sound effects are great, but they typically lock you into using the sounds only how they were recorded: dozens of blasts and bursts all happening at once.
The plan for the Fireworks and Firecrackers Sound Effects library was to do something different. The idea? To record isolated sound effects: pops, bursts, shrieks, crackles, and sparkles captured “cleanly” and not mixed with any other sounds. This would allow the fireworks sounds to be used in a wider variety of projects and to be pitched and warped for sound design. In short, the plan was to create a flexible sound library many people could use either for pyrotechnic effects, or to supplement sound design for gunshots, or other blasts and booms.
Recording Fireworks Sounds
There are two especially tricky aspects to recording fireworks sounds:
Fireworks Recording Challenges
1. Loud Fireworks Sounds
The first is that firework sound effects are loud. I have a sound effects decibel level chart over on Creative Field Recording. It lists fireworks at 150 decibels. That’s the same as a jet engine. Of course, fireworks are typically only that loud for very short periods. And, naturally, not every firecracker is that loud. However, in general, it presented a challenge that needed to be dealt with: the sound threatened to be too loud for the equipment, and risk being damaged during recording.
Most common portable recorders can handle only 120 decibels. Even few pro microphones can accommodate loud sounds (for instance, a Sennheiser MKH 8040 can only handle 142 dB). Today, 32-bit recording can help deal with this. However, at the time of recording, 32-bit recorders were not widespread.
Here are some examples of the loud fireworks we recorded (watch your ears!):
So accommodate for this, we applied pads and line cuts on the microphones and recorders. We also added distance and perspective to the microphones to diminish the perception of the loudness. The end result? The microphones capture the full dynamic of the fireworks of screams building from whimpers to wails, and sizzling fuse burns to machine-gun sounding rapid-fire bursts.
2. Fireworks Movement
The second challenge is that fireworks move. The easiest ones sputter and crackle on the ground. However, some fireworks sound effects pop loudly at ground level and then scream into the air to burst with an aerial spray of sparks.
To accommodate for both of these perspectives, we used an array of microphones. Some focused on the action on the ground. Others were placed at a distance to capture the spacious airborne blasts, shrieks, and fizzles. A mix of mock-ORTF and XY microphones captured a focused depiction of the nearby action, while the richness of a distant Neumann RSM-191 and DPA AB microphone array gathered the spaciousness of the aerial effects.
Technique for Recording Firecrackers
The first step to recording the fireworks sound effects was focusing on safety. Fire extinguishers, sand, and water were all ready. We used extended barbecue lighters to ignite the pyrotechnics from a safe distance. The recording area was free of anything overhead (such as hydro wires or trees), but more importantly, also free of any other objects that would be affected by falling debris. After each take the used cartridges and tubes were safely doused or smothered in sand.
We planned to record the fireworks on the two days before Canada Day. Why? Well, naturally there would be far more fireworks on the actual holiday. We needed clean, isolated fireworks sounds. So the only option was for a trial two nights before, and then a follow-up session the next night.
We organized the order of the fireworks to record the sounds based on style. We started with the ground-based, close-range cakes, cones, and firecrackers with the microphones nearby. As we proceeded to the mortars, Roman candles, and tubes, we rearranged the microphones to capture the space and distance of the aerial effects, moving farther back as the pyrotechnics became louder and more powerful. It was far easier, faster, and more consistent to record the same type of fireworks in sequence than to keep repositioning the microphones back and forth and adjusting recording levels each time.
We spent about $400 USD on the props. It’s not always clear how the fireworks would perform, or the sound they would make. Some were just a shower of noise, and not very interesting. For the second night we returned and bought more of the best fireworks – those with powerful blasts, hollow thumping launches, and characteristic airborne wails.
Mastering Firecracker Sounds
What’s the best way to edit fireworks sound effects?
The bursts and explosions were so loud that they overpowered everything else. So, editing focused on preserving the long, spacious “tails” after the initial blast. We were quite lucky to have a relatively quiet night for both evenings. There were no insects, few dusk birds, and very little nearby activity. During the editing stage, we removed some distant fireworks, and used a bit of iZotope RX’s spectral repair to get rid of overlapping dog barks, debris scattering, and so on. Most of the clips were clean as recorded, thankfully.
All fireworks sound effects were edited in tandem having the same length. This was done so sound designers could switch between close, medium close, and distant perspectives easily.
As a bonus, we processed the raw tracks into two additional flavours:
- a “pitched low” mix with deeper, heavier versions of the tracks to use as “sweeteners” for gunshots, explosions, and more.
- a “punchy mix” with the effects processed through a compressor (primarily Softube’s Chandler Limited Germanium Compressor) which transformed the raw effects into “over-the-top” beefy, powerful versions.
Fireworks Sound Library Curation
With the recording and editing complete, our team turned to describing and curating the sounds. What’s the best way to describe fireworks sound effects?
We started by organizing them by type: cakes, fountains, noisemakers, tubes, mortars and more – each of which have a distinctive sonic character to them. Online research and fireworks definitions helped sort the different types of fireworks and name them properly.
We supplemented that text with their product name to add a bit of flavour so that the clips would jump out in a sound list: “Mad Dog”, “Sidewinder”, “Screaming Banshee”, and other colourful names. For the last aspect we described the performance of the fireworks: “Launch, Burst to Wail”, “Launch, Burst to Sizzle, Aerial Explosion”, and so on. This “technical” name was paired with a human-friendly readable name.
The result? 508 sounds (1 raw set with 2 processed versions) in just over 5 gigabytes of carefully recorded, edited, and curated fireworks sounds.
Here’s a preview to the sound library:
Thanks for joining us for this sound library preview. Stay tuned! We will release the full library of fireworks sound effects next week. Join our free email newsletter to be notified when the collection is available.
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Field Recording 2022/03/29
Tags: firecrackers, fireworks, how to record