Simplicity and consistency is key to choosing the right surround sound capture for sporting events. It is important to choose a solution that is easy to deploy, simple to use and delivers consistent, phase-coherent sound, says Pieter Schillebeeckx With more and more consumers watching TV in HD and proudly setting up 5.1 surround sound systems […]
Simplicity and consistency is key to choosing the right surround sound capture for sporting events. It is important to choose a solution that is easy to deploy, simple to use and delivers consistent, phase-coherent sound, says Pieter Schillebeeckx
With more and more consumers watching TV in HD and proudly setting up 5.1 surround sound systems in the home, HD and 5.1 have become synonymous. In sports production, broadcasters are tasked with creating a realistic, phase coherent surround audio track to capture the excitement of a crowded stadium or the thundering beat of a world-class horse race. While there are several different ways to produce surround sound, the need for stereo downmix compatibility of any 5.1 in the broadcast chain can challenge even the best audio engineers. Furthermore, while many systems have been developed to capture a surround environment in a controlled setting such as a high-end concert hall, having the ability to translate this experience in an arena or stadium is tricky as setup times are short and ease of use and repeatability essential.
In its simplest form, audio for sporting events can be broken down into the following audio components: ambient sound to capture the feel and excitement of the venue and the crowd, effects microphones to enhance specific effects such as ball-kicks and the referees whistle, and commentary. While there are alternative methods to recording ambience, such as a dedicated stereo pair or a surround array, these approaches can be fraught with phase and imaging dangers. These methods do not fully take into account the needs of the broadcast chain where any 5.1 needs to be stereo downmix compatible both for SD with stereo delivery and for automated downmixing in the home. In addition, when events are captured week in and week out in the same location, or when the production group travels from venue to venue following a particular team, traditional surround approaches suffer from inconsistency and require a very skilled audio engineer to achieve high quality downmix compatible results.
There are many dedicated surround sound design techniques in use today produced by an equal number of manufacturers. These approaches include:
Decca Tree, a three-point, omnidirectional microphone array in a widely spaced equilateral triangle
Double MS, a three microphone MS setup with shared side mic signals for front and rear
Fukada Tree, a five-microphone version of the Decca Tree
The four microphone Hamasaki Square and IRT Cross systems
Some systems employ microphone elements from different manufacturers that are attached to specialised rods connected in different geometric shapes to realise the above list of surround options, while others are proprietary microphone/processing systems. One such system is in the shape of a horseshoe, another mimics a human head and yet another has four microphone elements in a dual figure eight configuration.
Many of these approaches require a lot of time and configuration to achieve the right sound and are not, therefore, particularly friendly with regards to a simple, repeatable deployment for a live sporting event. They can also entail extensive matrix processing to deliver the correct signal, while others deliver dedicated signals to an audio console which rely on the audio engineer to arrive at the best mix. While a lot of technology exists to record a pure surround sound field, translating that effort into the realities of television upmix and downmix workflows is an entirely different story. One system might deliver a great surround experience, but fall apart when collapsed down into stereo or mono, especially with sonic elements that should be in the center position moving to the left or right of a stereo mix. When this type of bad translation begins to get noticed at home, that is when the flood of phone calls reach the broadcaster.
The proprietary systems specifically designed to handle live events are the better choice for sports broadcasting. For example, there now exists technology based on a single mic design philosophy where all the elements necessary to produce a stereo or multi-channel surround signal can be attained through four precision-aligned, high-quality microphone elements. The core is made up of four audio elements that represent the front/back information (depth); the left/right information (width); the up/down information (height) and the central point from which the other three elements are referenced. As these four signals are completely phase coherent, resulting surround recordings can be collapsed to stereo or mono without the phase cancellation and high frequency differences encountered when summing together signals from multiple spaced microphones. By manipulating these signals in the related control and processor units, an engineer can choose how the microphone should be oriented and which elements to use for their surround ambience to address particular production needs, and all this from the comfort of the audio mixing position, without the need to physically move the microphone.
Using a world-class horse race as an example, a four element microphone could be placed above and in front of the starting gates facing in the direction of the horses. Because the microphone picks up 360-degrees and the engineer can rotate where the front of the microphone is facing, the mic can be directed toward the Grand Stand from the OB truck for the pre and post race programming. When the race is about to commence and the horses are in the starting gate, the microphone can be re-oriented to face the starting gate. In this way, the engineering personnel need only deploy a single microphone to capture the ambience for different event sections, with the action or close-up effects microphones and commentary seamlessly adding to the excitement of the event. Many of the alternative surround capture solutions require a technician to physically move the microphone system to achieve the same results.
Why not make life easier when it comes to surround capture? Choose a solution that is easy to deploy, simple to use and one that delivers consistent, phase coherent sound for any sporting/live event production.
Pieter Schillebeeckx is Product Manager for SoundField at TSL Professional Products Ltd.
