This month Pole Position Production is very proud to release the latest in our military battleground recordings: The Warfare Library 3 – Heavy Bombardment. It is the follow up to our previous collections Warfare 1 and Warfare 2.

While we’re quite happy to share these rare sounds of rocket sound effects, howitzers, and naval guns in the collection, we’re also proud of how the library came to be. So, in today’s post we’ll describe how the field recording session began, what happened on location, and how the Pole team gathered the recordings into the sound library we’ve just released.

Let’s learn more.

Recording at a Military Test Site

While the Warfare 3 recordings happened relatively recently, the genesis of the recording session began long before that.

Pole co-owner Bernard Lõhr grew up near Karlskoga, Sweden. Located about 250 km west of Stockholm, Karlskoga is well known as the home of arms manufacturer Bofors, a contractor for the Swedish military. For over 350 years, Bofors has made artillery equipment at the Karlskoga factory. Today it is home to Europe’s largest firing test site – a massive 50 square km munitions testing range sealed off from the public. Manufacturers from across Europe and the rest of the world rent the space to test their weapons.

Bernard had asked Bofors Test Center if Pole could record on their testing range. Initially Bofors had declined. It was only later when a suitable Bofors customer appeared that Pole was invited to record. After a successful first shoot, the Pole team were invited to return to Bofors testing range again and again.

An Opportunity – Recording Rocket Sound Effects

Pole’s first recordings at the Bofors testing range are available in The Warfare Library 2 and includes a session with a howitzer. The next time Bofors called, they were testing something new – equipment that would make incredibly rare recordings: naval guns, rocket launches and even more detailed recordings of cannons and howitzers (including incoming shells).

Before the shoot Pole learned that there would in most cases be no explosives in the missiles, and that the team would have full access to the entire firing range. This provided Pole with an opportunity – not only to record firing of rockets, cannons, and howitzers – but to place microphones within the firing range to capture the sound of shells incoming to the site of impact. Under such conditions, it would be possible to record the sound of the shells passing by overhead, flying through the air, and whistling to hit the ground with a spray of debris.

Equipment Planning

The Pole team set up microphones around the firing site. Each of them was tracked to a 32-bit recorder to capture the maximum dynamic possible – these weapons were loud! No pads were used. A mix of multi-channel, mono, and stereo microphones were used including Sennheiser 8000-series microphones, a pair of Schoeps, a Neumann RSM 191, PZMs, and others.

Arranging the microphones in the firing range was more challenging. With the exception of the rockets, the Bofors team had only a rough idea where the shells would land – after all, a bit of wind could change a shell’s trajectory. So, the Pole team needed to cover as many places as possible.

During the time needed to set up the weapons, a Bofors employee drove a member of the Pole team to various locations in the firing range to set up three different recording kits. At times these would be far from the firing site – such as with the Haubits 155 mm artillery, 30 kilometers away. Positioning was challenging – the microphones needed to cover a large area because the team didn’t know where the shells would land. So, microphones were aimed both towards the firing site and away from it to accommodate both under- and over-shooting.

The recorders were sync’d with timecode to the kits at the firing site to ensure easy synchronization in the edit suite, later. They were powered by high-capacity batteries that ran continuously and were changed at lunch.

Shattering the Sound of Stillness

At the first projectile session, Pole co-owner Max Lachmann set up behind an armored wall at the firing range’s impact site, while co-owner Bernard Löhr and Sweet Justice’s Ben Minto recorded at the firing site itself. The impact site was a full 30 kilometres away from the firing site – Max found himself at a tranquil location behind a headland near the sea at sunrise as birds sang and mist rose from an icy lake. He placed a Holophone, Sanken CSS-5, and some Sennheiser MKH 8060 shotgun microphones on the other side of the lake pointing in the direction of the trajectory, as well as submerging a pair of hydrophones within the lake itself.

As the session began, the firing crew announced the first shot over the radio. However, due to the distance, the sound itself was delayed, with the sound of the shot arriving after 10 seconds. Then, without warning nearly 25 seconds later, the lakeside stillness was suddenly shattered as the projectile exploded with an ear-splitting blast and scattered shrapnel in all directions, skipping across the lake. The crew fired again and again at the same location with thundering impacts – followed by a whistling approach and the artillery blast as the earlier sounds caught up over the distance.

"It was spectacular,” Max said – the blasts ripped through the calm countryside and echoed across the open firing range, slowly diminishing into stillness before erupting again.

Haubits 155 mm Howitzer Sounds

At a later session, the Haubits 155 mm howitzer was similarly incredibly loud – the gun was so powerful that each time it fired the air pressure from the shockwave moved a nearby bunker’s heavy metal swinging door.

At the firing site, the Pole team set up microphones around the gun and ran cables through a hole in a wall to record from inside the bunker.

The team were very lucky to record during early spring and late fall; no birds or insects interfered with the recordings. The Bofors crew very patiently and kindly remained quiet until the bombardment was finished. The result? Long, clean tails:

The microphones at the impact site captured incredible movement detail from incoming shells. They were tremendously loud – the shells were rigged to explode while in the air causing tremendous sonic effects and debris raining down to the ground. The Bofors team in this case had a pretty good idea of where the projectiles would explode, so the Pole team, joined by Philip Eriksson, Audio Director of Hazelight, were able to place the recorders and mics around a somewhat specific location. They could then see the fireworks from inside a safe bunker out in the woods, some kilometers away from the explosions and debris.

Bofors 57 mm Naval Automatic Gun L/70 Sounds

This Bofors 57 mm Naval Automatic Gun L/70 was controlled remotely from inside the bunker. It was completely automated, which provided the chance for the Pole team to mount microphones inside the gun to record mechanism noises when it reloaded:

Unlike the howitzers, it shot 1 km away at a huge pile of dirt. It sounded like a massive pistol:

Rocket Sound Effects

The Bofors team also fired 2-3m long 122 mm Czech rockets. The rockets shot straight up in the air with a blaze of fire then took off at the speed of sound.

The Pole team pointed some microphones in the direction of the missile to capture the ignition, and others pointing in its path of travel to follow it through the air. Here’s how it sounds:

With the rockets, the Bofors team were a bit unsure where they would land. So, the Pole team had three locations with microphones (including a Neumann RSM 191, Sennheiser MKH 8040s, and Ehrlund M1s) pointing towards and away from the firing position in an effort to capture the incoming movement of the rocket. If the missile overshot, the second microphone would capture the pass overhead. Here’s an incoming take of the rocket sound effects:

Editing Howitzer, Cannon, and Rocket Sounds

Editing any sound effect can be complicated by the presence of planes, traffic, and wind. However, the Warfare 3 recordings were so clean that it made the work simple – it was an unusually easy library to master.

To ensure that the long tails were clean and problem free, co-owner and editor Mats Lungdren used a limiter when auditioning to bring up the tails. This allowed him to put a magnifying glass on the sounds to scrutinize every second of the tail and spot the flaws he wanted to remove. The goal was to keep as much of the long tails before cutting. This resulted in exceptionally long, clean tails.

At times staff footsteps had to be trimmed or removed with iZotope RX’s spectral repair or spot gain reduction. Birds and clicks were removed with spectral repair as well.

The Warfare Library 3 – Heavy Bombardment