Microphone placement is essential for capturing high-quality audio. What do I imply by microphone placement? Fairly merely, it means the place you resolve to position the microphone. The purpose in microphone placement and just about all audio recording is a excessive signal-to-noise ratio.
Sign to Noise
Let’s break that down. The sign is the factor you wish to document, and the noise is what you do not wish to document.
To illustrate for a second that the sign is an individual talking—so you’ve a microphone and the topic you will document. What’s the noise? The noise is every part that is not the voice you are making an attempt to document.
These noise sources can come from all kinds of locations. You may have environmental noise: issues like HVAC (cooling and heating), computer systems and different gear on set, or issues like basic speaking and visitors. There’s an ever-growing record of issues that might be thought of environmental noise. On high of that, there’s additionally noise that is generated by sign processing within the recording course of. Some microphones will generate a little bit of noise. Preamps will generate noise. The analog-to-digital converter generates noise. All of these you do not need.
On the digital facet, that noise usually feels like white noise or hissing, and relying on how loud that’s, it may be problematic. With environmental noise, a little bit bit could also be OK, but it surely’s nonetheless not the factor you are making an attempt to document. So the concept is that you’ve got the factor you are making an attempt to document and the factor you do not, and what you wish to do is get a better ratio of what you wish to document (the voice) and a decrease ratio of noise. So how do you do this?
Getting a Good Ratio
To get a superb signal-to-noise ratio, you may wish to have your microphone near the sound supply. Microphones aren’t magic—they’ll at all times work in keeping with the ideas of physics. The nearer you get the microphone to the sound supply, the extra of that sound supply will probably be picked up from that microphone.
Let’s describe a scenario right here. Let’s fake that we take a microphone and we place it 3 ft from our sound supply. Now, you are going to hear your particular person talking, and also you’re additionally going to listen to the surroundings that they are in. Regardless of the place they’re, you will get a little bit of reverberation.
In an effort to get a usable sign out of that microphone, you are going to have to show up the preamplifier. You may have to extend the acquire, if you’ll, to get the voice at an appropriate degree. Once you do this, nevertheless, the noise may also be amplified. It’s because the microphone would not know what it is listening for.
So what is the answer? You may wish to transfer the microphone nearer. Once you transfer the mic nearer, the ambient noise stays usually the identical, however as a result of the microphone is nearer to the sound supply, the sign turns into comparatively stronger. So what you may have to do to take care of a correct degree is take your preamp and switch it all the way down to get the voice at an acceptable degree as a result of if it was the identical degree at three ft away and you progress it fairly near the sound supply, will probably be method too loud and we’ll get into clipping.
The impact now could be that the voice is similar because it was when the microphone was three ft away, however as a result of we have turned it down, the ambient noise within the area has additionally been turned down due to its relative place to the microphone. You’ve got successfully given your self a excessive signal-to-noise ratio. That is the purpose for recording—it is what you wish to hear. The additional away that mic is, the extra ambient noise you may get, and you may additionally improve the reverberation. Now, which may be what you need, however for now we do not, so get the microphone near the sound supply.
Microphone Pickup Patterns (Polar Patten): Omnidirectional and Unidirectional Microphones
One other issue that performs into mic placement in getting that top signal-to-noise ratio is the microphone’s pickup sample, also called a polar sample. All microphones have a polar sample, and that signifies how delicate a mic is to the sounds coming from totally different instructions.
So lets say for a second that you simply’re in a darkish room, and there is a single lightbulb hanging from a wire within the centre of the room. The sunshine will radiate in all instructions from the sunshine supply. That is equal to a microphone with an omnidirectional pickup sample, a mic that’s delicate in all instructions.
If we add numerous shades to form the sunshine, we are able to begin to make our mild supply extra directional. If we equate that to microphones, we’re moving into unidirectional microphones. That is when the microphone is delicate primarily in a single course. These two forms of microphones are actually all you could contemplate. There’s one other sort of microphone, the bidirectional mic, which data in two instructions, but it surely is not relevant or related to such a video manufacturing.
Microphone Shapes: Cardioid, Tremendous-Cardioid, Hyper-Cardioid, and Shotgun Polar Patterns
Within the realm of unidirectional microphones, you’ve a bunch of various shapes that decide how delicate the microphone is to frequencies in that one basic course.
A cardioid sample is so named as a result of it resembles an enormous coronary heart, and it’s most delicate immediately in entrance of it whereas rejecting sounds immediately behind it. If we take that cardioid sample and make it narrower, it is known as a super-cardioid, and if we make it even narrower, it is a hyper-cardioid. As they get narrower, they begin accepting a little bit of sound from the rear. I ought to say that these shapes for unidirectional polar patterns are generalizations. You probably have two totally different cardioid microphones, the sample might differ.
If we proceed to slim this form, we’ll find yourself with a shotgun sample. This sample has a slim acceptance from each the entrance and the again of the microphone, and it does a improbable job of rejecting sounds from the edges.
Proximity Impact
Figuring out in regards to the polar sample of a microphone is necessary as a result of there’s an impact that may occur with unidirectional microphones known as the proximity impact. The proximity impact in audio is a rise within the bass response or low-frequency response when the sound supply is near the microphone.
That is good to know as a result of in case you’re utilizing unidirectional microphones and the space is various a superb deal, it will trigger the recordings to be a bit uneven, and that may be problematic. This does not occur with omnidirectional microphones; they do not present any proximity impact. Whatever the distance, the mic ought to have the identical sound high quality tonally. With a unidirectional microphone, nevertheless, it turns into rather more bass-heavy because it’s moved nearer to the sound supply.
That is It!
Figuring out about signal-to-noise ratio helps you perceive that you could get the microphone near the sound supply. Figuring out about polar patterns helps us perceive methods to orient the microphone in order that it picks up the sound you need it to select up.
Now that you’ve got an understanding of mic placement, signal-to-noise ratio, and polar patterns, you are prepared for the subsequent tutorial. You are going to learn to get the audio from the microphone into your digicam.
