This week I saw a viral post on Facebook regarding survivorship bias (a subset of selection bias) regarding planes in WW2. Survivorship bias is the logical error caused by concentrating on the people or things that made it past some selection process and overlooking those that did not, typically because of their lack of visibility. This can lead to false conclusions.
During the war researchers from the Center for Naval Analyses looked at the damage done to aircraft that had returned from missions and they recommended that extra armour should be added to the parts of the aircraft that showed the most damage.
Mathematician Abraham Wald noted that this logic was flawed as these planes still made it back to base. The areas where there was no damage to the returning aircraft would be the areas in which the plane is unlikely to survive and therefore these parts should be re-enforced.
It might seem a bit off-topic but this example lead me to think about when logical errors creep into music production. The first thing that came to mind is microphone choice.
The most obvious logic for choosing a microphone is to ask:
"What sort of frequencies does this instrument produce?"
Then you would only audition microphones that meet that criteria. For example, cymbals produce high frequencies so my overhead microphones need to be condenser mics.
However, in most cases the best process is to listen to the instrument in the live space and ask:
"Does this source need any help to sound better than it currently does?"
In this case, you might find that the cymbals on the drums are already too bright and using a condenser microphone might exacerbate the issue. In fact, I am a big fan of ribbon mics (especially Coles 4038) on overheads because it often makes the drums sound bigger and less fatiguing.
It is a recording mantra of mine that "fixing problems as early in the chain as you will lead to more natural results" but there are plenty of occasions where changing the room, player or instrument just isn't an option. In these cases, maybe try a mic that has the opposite characteristics to the source.
This is the reason that a lot of engineers like ribbons on brass, it naturally softens the brash and edgy top-end and allows them to sit in the mix more.
Sometimes, you will want to enhance an area that is important to the sound and mic choice can do that. Jazz and big band engineering legend Al Schmitt said:
"I don't use any EQ when I record, I use the mics for EQ"
This is, of course, an over-exaggeration for most modern genres but the point is valid. Try to utilize the properties of elements earlier in the chain rather than reaching straight for EQ.
Let me give you an example of this, that you probably use all the time without knowing it. A lot of people assume that dynamics are used on the shells of a drum kit only because they are less sensitive and can withstand higher SPLs. Whilst this does play a big part of it, I would argue that there are two aspects of a typical dynamic mic that are naturally suited to drum shells:
1) Transient response, a byproduct of less sensitive microphones ist that they typically respond less accurately to transients. From a scientific perspective, this is a bad thing. Operationally though, this can be a good thing because the natural "rounding off" of the transient can give you more headroom without too much distortion.
2) Dynamic mics often exhibit an upper midrange frequency boost and this is great at making the sound of the stick hitting the drum more pronounced and therefore make the drum sound more aggressive.
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