Spot miking (also known as accent miking) helps us to emphasize certain instruments and sound sources in dense environments.
What Is Spot/Accent Miking? Spot/Accent miking is the act of close-miking certain sources in dense acoustic environments such as orchestras. Spot miking, when done effectively, will concentrate on a single sound source (ie: a solo instrument in the orchestra) and allow for greater flexibility and clarity in the audio mix.
Let’s discuss spot/accent miking in more detail to better understand why and how we use this technique.
What Is Spot/Accent Miking?
A spot/accent microphone refers to a microphone that is used to close-mic a specific sound source within a larger ensemble that would otherwise be captured by a more distant microphone array.
In other words, a stereo or surround sound miking technique may be used to capture the sound of a large ensemble of instruments while an accent mic is positioned near a quieter or particularly important instrument within the ensemble.
What exactly is close-miking, though?
What we typically mean by close-miking is a microphone-to-sound source distance of a few feet at maximum and less than an inch at minimum. There is no one way of close/spot-miking an instrument or sound source.
Close-miking aims to acoustically isolate the intended sound source as much as possible. This means having a high signal-to-noise ratio where the intended sound source makes up the “signal” and everything else makes up the “noise.” All of this, of course, while still capturing a realistic and clean audio representation of the sound source.
So the positioning of a close-mic relative to its intended sound source depends on many factors. Some of these factors include:
- Acoustic environment (reflections and reverberations).
- Frequency profile of the sound source (lower frequencies require greater distance to develop).
- Proximity to other sound sources (microphone bleed).
- Polar pattern of the microphone (directional mics may be placed further while still capturing the intended sound source).
- Proximity effect (the rise in bass response of pressure-gradient microphones as they are positioned closer to a sound source).
Note that in modern multitrack recording, we often close-mic many of the sounds sources and instruments. Each “close-miking” microphone in these situations could be considered a spot mic. However, the term “spot mic” generally refers to a mic used to augment a certain element in a larger ensemble rather than the mics used in close-miking techniques.
To use the example of the orchestra, if we were to close-mic each and every instrument, we wouldn’t necessarily call these mics “spot mics” (although we could). If we were, on the other hand, to use a Decca Tree stereo-miking technique to capture the full orchestra and close-mic only the oboe and trumpet (for example), these mics would certainly be considered spot mics.
To learn more about microphone positioning, check out my article Top 23 Tips For Better Microphone Placement.
Pros And Cons Of Spot-Miking
From the initial statements on spot-miking, we infer that the main reason for using spot mics is to accentuate important instruments within an ensemble that are paramount to the performance.
Another reason to use a spot-mic could be to accentuate an instrument that isn’t quite as loud as it needs to be. Sound reinforcement is important to supplement a mix but is not the main motive for utilizing spot-mics.
Of course, with any microphone technique, there are pros and cons. Let’s quickly list them out before diving into each pro and each con in greater detail.
The pros of spot-miking include:
- Creative control over the level of the spot-miked instrument.
- A relatively isolated capture of the spot-miked instrument.
The cons of spot-miking include:
- The room sound is effectively reduced.
- Increased transient response.
- Increased bass response.
- Incomplete development of the intended sound source.
- Small changes in mic or instrument position have a great effect on the microphone’s pickup of the instrument’s sound.
Let’s first look at the pros.
Spot-Miking Pro: Control Over Levels Of The Spot-Miked Sound Source
The beautiful thing about spot-miking is that once the microphone is set up, we have full adjustment of the mic’s level in the mix.
In fact, we can set up a spot-mic and, after listening to the mix with varying amounts of the spot-mic signal, decide that we don’t want the mic’s signal in the mix at all.
It’s nice to have options (within reason), and so spot-miking is great for that as well.
Usually, though, spot-mics come in handy when a particular instrument is taking a solo or is the centre of attention in other ways. At these moments, simply boosting the spot-mic signal a few decibels or even introducing the signal into the mix can help tremendously in accentuating that instrument in the mix.
When that section of the performance is done, simply bring the levels of the spot mic back down and the spot-miked instrument will blend nicely into the overall mix once again.
Spot-Miking Pro: Sound Source Isolation
Of course, in order to effectively boost the level of a single instrument in a mix, it’s important to have that instrument as isolated as possible.
Physical isolation of an instrument in a an ensemble or live stage performance is difficult indeed. This is especially true when the musicians (and their instruments) are close together.
Spot-miking, when done with directional mics (cardioid and cardioid-type mics), will do a decent job at isolating a particular sound source.
To learn more about cardioid and cardioid-type microphone polar patterns, check out my articles What Is A Cardioid Microphone? (Polar Pattern + Mic Examples) and The Complete Guide To Microphone Polar Patterns, respectively.
This is not because the mic will not pickup the sound of other instruments within the ensemble. It certainly will. However, when close-miking, the intended sound source will be much louder in the mic signal than the other sound sources, which gives the illusion of isolation through excellent signal-to-noise ratio.
The use of directional microphones further reduces the pickup of off-axis unintended sound sources and “focuses” the microphone pickup more on the intended sound source.
And now for the cons.
Spot-Miking Con: Poor Room Sound Capture
This is the flip-side of sound source isolation we discussed as being a pro.
Note that having very little room sound in a mic signal can also be pro, especially if the room doesn’t sound very good or if the instrument is positioned poorly in an acoustic space.
However, I’ll write this down as a con when talking about spot-miking because it may cause the spot-miked instrument to sound a bit uncanny if the mic signal is boosted too much.
In audio mix, we deal with dimensions. The “width” of a mix depends on the stereo image and panning of the microphones. The “depth” of a mix depends on space and reflections in the mic signals.
When spot-miking to supplement a full ensemble’s microphone array, the spot-miked instrument will naturally sound up-close while the mic-array capture will sound further away.
This is not necessarily a bad thing, but can begin to sound uncanny if the spot-mic signal is too present in the mix.
Spot-Miking Con: Increased Transient Response
To continue on the theme of uncanniness, close distance miking increases the transient response the mic has to its intended sound source(s). Spot-miking a particular instrument, therefore, will cause that instrument’s transients to stand out more in the mix.
The distance between the microphone array and the ensemble allows the individual transients of each instrument to blend together and reduces the sharpness of the transients before they reach the microphones.
A close mic, however, will capture these sharp transients from the intended sound source.
This isn’t always a bad thing. An increased transient response could allow more percussive instruments to stand out more without having the spot-mic too present in the mix.
However, it can be a bad thing if the spot-miked instrument sounds overly percussive and doesn’t fit in the same acoustic realm as the other instruments.
A simple solution to this problem is to distance the mic back a bit or point a directional mic slightly away from the instrument. Do this sparingly to avoid impairing the isolation of the sound source.
Spot-Miking Con: Increased Bass Response
Oh our good friend the proximity effect.
As discussed, directional microphones are advised when spot-miking. Unfortunately (or not), directional microphones exhibit what is known as the proximity effect.
The proximity effect basically states that as a microphone moves closer to a sound source, its bass response to that sound source increases.
To learn everything you need to know about microphone proximity effect, check out my article In-Depth Guide To Microphone Proximity Effect.
So if we decide to spot-mic a sound source at a close distance, it’s imperative to listen to the low-end response in the mic signal.
This isn’t always a bad thing but low-end signals can easily muddy a mix and eat away at headroom within the mix.
High-pass filters are often our best friends when it comes to close-miking sources with directional mics.
For more information on microphones and high-pass filters, check out my article What Is A Microphone High-Pass Filter And Why Use One?
Spot-Miking Con: Incomplete Development Of The Sound Source
Sound is made of frequencies between 20 Hz and 20,000 Hz. These frequencies have corresponding sound wave lengths between 17 meters and 17 millimetres.
Even a relatively low bass sound frequency of 80 Hz, we’re dealing with a wavelength of 0.43 meters.
It’s also the case that sound tends to propagate through a medium in an omnidirectional fashion. That is to say, all directions simultaneously (though the bodies of instruments and musicians often dampen the sound from travelling in certain directions).
All this is to say that sound takes some amount of distance to fully develop.
To test this, try listening to a friend speak (or play an instrument) with your ear at their mouth (or very close to the sound producing element of their instrument). Now back up and listen to them talk at a practical distance.
Not only is their voice quieter, but it’s also fuller in some way. The sound waves from their vocal cords have had a chance to develop in the medium between the vocal cords to your ears.
The same goes for close-miking instruments. Positioning a microphone too close to an instruments will effectively cause it to capture an “incomplete” sound of the instrument.
This is particularly true with larger instruments than produce sound from different resonant bodies, strings, holes, etc.
Spot-Miking Con: Potentially Inconsistent Sound Capture
Finally, spot-miking can yield a potentially inconsistent sound capture. This is particularly true of small insturments and the musicians that play them if the musicians have a tendency to move while performing.
Because we’re positioning the microphone so close to a source, any change in distance will be relatively large compared to an equal change in distance of the main microphone array.
For example, if a microphone is positioned 10 cm from an insturment and that instrument moves 5 cm, that’s a 50% change in distance. This seemingly small change can drastically affect the transient and bass response of the mic along with the isolation of the instrument and the signal and signal-to-noise ratio of the instrument in the mic signal.
However, if the main microphone array is 5 meters away (500 cm), moving the mics 5 cm will change the distance by 1% and have practically no effect on the microphone capture.
One simple way to avoid this is to attach the spot-mic directly to the smaller instruments that require spot miking. This way the musician shouldn’t have to worry about moving around. The mic will always be at the same relative position to the instrument.
I commonly recommend the Shure Beta 98H (link to check the price on Amazon) as a clip-on spot-mic for instruments.
To learn more about my microphone recommendations, check out My New Microphone’s Recommended Microphones And Accessories.
What is XY mic placement? XY is a coincident pair stereo miking technique the utilizes two cardioid microphones (typically pencil mics). It has their capsule placed as close together as possible (generally one on top of the other) and angles the mics 90° – 135° from one another, pointing them both along the horizontal plane.
The XY miking technique is featured in the following My New Microphone articles:
• Top 8 Best Stereo Miking Techniques (With Recommended Mics).
• What Is A Coincident Pair Of Microphones? (With 2 Techniques).
What is ambient miking? Ambient miking refers to the technique of placing microphones at such a distance that the room sound (reflections and reverberation) is more prominent than the direct sound of the sound sources. Ambient miking is commonly used to capture audience noise or the natural reverberation of an acoustic space.