Formula E broadcasters achieve great audio with Bubblebee Industries

The sound recordists responsible for delivering 2020’s ABB FIA Formula E coverage to the BBC made good use of Bubblebee Industries technology to help circumnavigate the impact of Covid 19.

Like so many sports,?Formula E?faced challenges because of the pandemic. Normally the fully electric, single-seater cars race around major city centres in front of thousands of spectators but due to the pandemic that was deemed unsafe. After months of deliberation, a solution was found – namely to complete the season by holding six races over nine days, behind closed doors, at Berlin’s iconic Tempelhof airport. Live TV coverage was provided by host broadcasters Aurora Media Worldwide and North One TV, known as Formula E TV, who supply the international and English host broadcast feed to channels such as the BBC, Eurosport and Mediaset.

Paul Halstead, Formula E’s Sound Supervisor, heads a dedicated crew of sound engineers, many of whom have extensive live broadcast experience and have been involved in Formula E since its first season six years ago.

“We work as a team but we have very distinct roles,” Paul Halstead explains. “Scott Morton?looks after ENG crews and is involved with the live presentation element, while I handle mic allocation around the track and mixing the international feed, along with any additional race support presentation.”

For the Berlin races, Scott and Paul had to contend with the German Government’s social distancing rules, which meant making changes to how the audio was captured. Handheld microphones shared between interviewers and drivers were obviously out, so they switched to boom microphones and used Bubblebee Industries’?Spacer Bubble?to get the right balance between wind protection and audio transparency.

“Switching to boom mics was a major safety protocol and we used them for more than 80% of our ENG and live presentation audio,” Scott Morton explains. “In this new landscape, presenters can’t get close enough to the drivers to share a handheld mic, and our sound engineers are not allowed to touch the talent so we can’t easily fit lavaliers. Our solution was to give presenters their own stick mic and use a boom mic to capture the interviewee’s responses.”

Scott adds that the?Spacer Bubble system?proved a real winner during the event because it can be easily adapted to suit the weather and ambient noise levels. The slip-on modular windshield solution for shotgun microphones is specifically designed for changing conditions and features a noise-free mesh base with coarse foam inside and a specially designed rubber mount that can be left on the boom or camera mic. The foam and mesh are ideal for indoor recording, while the included Long-haired fur Spacer Cover and Short-haired Spacer Cover (available to buy separately) are available for outdoor recording and can be quickly fitted to provide wind protection in all kinds of weather.

“The modular nature of the Spacer Bubble system was perfect for us because we could get variations in the shielding,” Scott Morton says. “Other systems are full-on fur or nothing. We like the flexibility this system gives us because it means we are able to adapt to changing weather conditions much more quickly. We used them with various R?de and Sennheiser shotgun microphones and got excellent results. As so much of the audio for the Berlin event was captured on boom mics, Bubblebee Spacers were very much in evidence – especially as we didn’t worry too much about booms being in shot because there was so little we could do about it.”

But what's the difference between the Long and Short-Haired fur covers? Here's the long and the short of it...

The Science Behind Wind & Sound: What’s the difference?

Sound is energy that causes air molecules to vibrate at a frequency. Wind is the energy of air molecules moving from point to A to point B at velocity.

Sound energy can travel through both air molecules which are stationary and moving air molecules (wind).

Think of it as a river or lake; if you throw a pebble into a lake, it will create ripples around a stationary point. If you throw a pebble into a moving river, it will still create ripples that will travel, included in the flow of the river.

Illustration: How air molecules move in sound or wind

The human ear interprets vibrations that travel through air particles as changes in air pressure. A microphone’s diaphragm does the same thing - interprets changes in air pressure as the molecules vibrate back and forth. Wind also causes a change in pressure, causing unwanted sound in a recording as a result and stronger winds can even cause the mic diaphragm to overload.

A note on ‘wind noise’: moving air molecules make no sound inherently. The sound we perceive wind to make is always the result of these moving molecules hitting a surface of some sort, causing friction, or sound caused by the movement of these surface objects. A classic illustration of this would be the sound of air moving through trees, causing the branches and leaves to move, shake and collide.

Illustration: Wind creates increased air pressure and friction noise when meeting a surface

Omnidirectional or Directional Microphones:

Omni-directional mics measure the overall air pressure around the mic capsule. The diaphragm and backplate contain a sealed off unit of air and therefore measure the differences between pressure inside vs outside, regardless of which direction it’s pointed in. Generally, the construction of Omnidirectional mics means the diaphragm is a more robust material than that of their directional counterparts. Omni mics can handle higher direct wind speeds before overloading the capsule.

Directional microphones use a more sensitive diaphragm material to achieve ‘directionality’ they measure the differences in pressure in front of, or behind the diaphragm. This phase offset of the sound energy results in smaller increments of difference and the diaphragm material is usually more?flexible to pick these differences up effectively. Due to the softer diaphragm of a directional microphone, their capsules can be particularly susceptible to wind and overload quicker than Omni mics.

Illustration: differences in the construction of omnidirectional and directional microphone capsules

The goal of our wind-protective gear is to create a safe, still space around the microphone capsule to allow it to function as closely to how it would in a still, windless environment.

Fur and Wind Protection:

In nature, animals living in the wild have coats of fur to help protect them against the elements like wind to keep them warm (there's a reason highland cattle have so much of it, being native to the windy Scottish Highlands and the Outer Hebrides!) Fur allows the wind to slow down before reaching the skin and thereby holding a pocket of warmer air next to the skin and protecting the animal from windchill.

The highland cattle (we really do think they’re cool!) have a fur coat that consists of a variety of different lengths, some strands of which reach up to 33cm (13”) in length. While our imitation fur doesn’t quite boast the same extremes, the principle behind it is similar when protecting your microphone!

We’ve taken our cues from the animal kingdom and created a dense multi-pile, super-soft faux fur. This allows wind to slow down gradually as it collides with the windshield’s fur piles, from the outside inwards.

Illustration: Multi-pile fur in the dispersion of wind energy

This forgoes a lot of the ambient noise which can be caused by larger flatter surfaces as the wind hits them – also the reason our strands of fur are so fine. The open mesh base of The Windkiller and Spacer Bubble uses a very porous acoustic foam to then create a neutral space around the mic. All this is to allow it to function as closely to its original specs as possible.

Why Are There Two Different Lengths of Fur?

Simply put, the longer the hair, the better protection against the wind!

However, covering up a microphone in any capacity is always going to have an effect on the way that the microphone captures the audio frequencies around it. There will always be a compromise. The?design and construction of?our wind-protection solutions?allow you to find the perfect balance to ensure your recordings are protected from harmful wind noise while retaining as much natural transparency as possible.

Because the velocity of wind outdoors isn’t a constant level, we developed a short-haired version of our fur. This allows your mic to retain even more of its original frequency response, whilst protecting against lower-mid level winds. The visual aspect of the short-haired fur is also perfect for use with on-camera mics, to ensure any potentially longer strands of fur stay well out of the shot.

If you’d like to see and hear the differences between our wind-protection solutions,?head to our YouTube channel?to watch us test them out in a variety of different and windy locations.

Have a windy day!