- Is a Microphone Array different from a Microphone?
- What is a Microphone Array used for?
- How many transducers can be found in a Microphone array?
A Microphone Array is a term used to describe a scenario where any number of microphones/transducers operate in tandem. They endure use in many fields, including Telephonics, Robotic navigation, surround sound, and hearing aids.
However, in this article, we will focus more on applications related to everyday Music Production, including techniques such as Binaural Recording techniques and Hi-Fi original recordings.
How Do Microphone Arrays Work?
A microphone array generally comprises a group of omnidirectional microphones, directional microphones, or a combination of both types of transducers. A common Microphone Array will generally utilize two working Microphones however the largest Microphone Arrays in the world contain thousands of transducers.
The function of a Microphone Array remains the same as a normal Microphone. It is simply the increased number and physical spread of the devices that make it different.
By employing the use of multiple Mics over a physical space, it is easy to imagine how this arrangement can yield stereo, quadraphonic, and, further, surround sound-enhanced recordings not obtainable with mono sources.
Blending these sources together can yield fantastic results for the listener if done properly. As a result, Microphone Arrays have become a standard in many facets of the audio industry.
Matching Microphones: Considerations
Now that you have a basic understanding of what a microphone array is, it is important to know what factors need to be considered when selecting the Microphones you wish to match within the composition of your array.
The first thing to consider is the phase relationship between the microphones. In basic terms, phase alignment is essential for all the Microphones to commence recording the sound source simultaneously. If there is a time delay between microphones, this will lead to unpleasant artifacts in the recording, such as phase cancellation, dead spots, comb filtering, and a lack of depth within the recorded audio.
There are various methods to ensure that multiple microphones are in phase. However, we will not have the time to go into depth on these in the scope of this short article. For the sake of conclusiveness, I will mention that correlation meters, delays, mic placement, and devices such as the Little Labs Phase alignment tool are all methods of checking and ensuring that your microphones are in phase.
Another factor to consider when matching microphones for a Mic Array is directionality and polar patterns. Using microphones with a different directionality will also result in undesirable recording quality and a lack of balance within what the Mic Array captures.
Omnidirectional and uni directional Microphones are commonly used in Microphone Arrays and are a suitable choice for most applications. Regardless of which you choose to incorporate into your microphone array, it is essential that all microphones in your Mic Array share the same directionality.
Sensitivity is the final thing to consider when selecting Microphones for a Mic Array. All transducers used within the array must be of a similar gain level. Failure to ensure this will result in some microphones in the array being louder than others, leading to an imbalance and undesirable sound captured within the recording.
Gain can be controlled via numerous sources but is most easily set by the gain trim pots on our mixing console, audio interface, or another device. Some microphones also feature pad switches that can reduce the gain by a predetermined decibel level, often displayed on the mic chassis or within the instruction manual.
Microphone Array Use In Music Productions
Mic arrays pose great value in various applications for musical productions. Engineers have long utilized mic arrays to capture orchestral ensembles as this method of recording will provide a substantial stereo field and capture the room’s essence during the recording process.
On the other end of the spectrum, mic arrays have also developed a considerable following amongst engineers who capture live concert performances such as Rock, Hip Hop, and Jazz performances. If an engineer is to blend the sound of the mic array with the sound of the close mics on each instrument, they can achieve an imposing sound stage. However, it is important to be mindful of phase when combining these various sources together.
Microphone Arrays have become commonplace within modern-day society, finding uses within Medical, Domestic, and even Military fields however, one cannot underestimate the importance they have garnered within music production and audio engineering circles. Employing a microphone array within your own studio might just be required to bring new life to your productions.