[Jay] OK, now it’s time to talk about microphones. We’ll discuss what a microphone is,
how it works, and we’ll take a look at a couple different types of microphones
that can be used for recording birds in the field.
Microphones convert real-world sound into an electrical signal that can be captured by a recorder.
Incoming sound pressure waves vibrate a thin,
electrically charged membrane, called a diaphragm, inside the microphone.
The movement of the diaphragm creates an electrical signal that travels through
the microphone cable to the recorder, where it’s converted to a digital sound file.
Microphones can either be omnidirectional, which means they capture sounds from all directions,
or directional, meaning they emphasize sounds coming in from a certain direction.
Smartphones and small recorders typically have small, built-in omnidirectional microphones.
You can record bird songs with these kinds of microphones,
but you’ll also pick up a lot of unwanted background noise.
With good technique, they can produce reasonable results,
but don’t help you hone in on a target like a directional microphone.
There are two types of directional microphones for recording birds:
the shotgun microphone and the parabolic reflector, or parabola.
Shotgun microphones consist of a hollow tube surrounded
by a series of slits, with a diaphragm at the back.
As sound waves travel towards the microphone, ones from directly in front easily pass through
the barrel to the diaphragm, where they are converted into an electrical signal.
Sounds coming from the sides travel through the slits,
which slow them down, causing some noise cancellation.
This means that sounds from directly in front of the microphone will be louder than
the sounds coming in from other directions, providing more focus on a target bird.
Shotguns are smaller and less cumbersome than parabolas, and often less expensive.
They’re also easier to aim, especially while recording moving targets.
Okay, now let’s talk about parabolas.
These microphone setups take more practice to use but can result in beautifully clean recordings.
The microphone in a parabola is actually omnidirectional by itself.
It’s the parabolic curve of the dish that provides the directionality.
Sound pressure waves traveling straight into the dish reflect towards the microphone at the center.
This means more of your target sound can be collected by the dish
and focused at the microphone, resulting in an amplified signal.
In contrast, sounds from other directions reflect out of the dish
and are not focused at the microphone.
The amplification and resulting directionality the dish provides make your subject stand out
from the background, much more than it would with a shotgun, (bird chirps)
giving you the opportunity to make a very clear recording of an individual bird.
But there are downsides.
Parabolas are bulkier, and can be more challenging to aim.
The difference between being on target and even slightly off target can be quite noticeable.
(birds singing, alternating louder and softer)
In addition to the microphone itself, there are a few accessories that you really need for recording birds.
The fluffy exterior of this shotgun is a windscreen.
It traps a layer of air around the microphone to protect it from gusts of wind,
while still allowing sound waves to pass through easily.
Even a light breeze can create a lot of noise when it hits a microphone, (wind noise)
so it’s important to use a faux fur or foam windscreen when recording outside.
The microphone inside a parabola usually has some type of protection around it as well,
typically a layer of fabric or foam.
Another key piece is the shockmount, the handle you use to hold a shotgun microphone.
It helps reduce handling noise that might get created from holding the microphone directly.
Handling noise is one of the most common forms of unwanted noise,
and with a good shockmount, you’ll make much cleaner recordings.
Finally, all microphones need a power source.
Many microphones can take a battery in the microphone itself.
And some recorders can supply power through the cable, a feature known as phantom power,
which conveniently removes the need for an additional battery.
Your microphone is your window into the world of sound, so consider your goals for recording
and choose an option that best fits your style and the type of recordings you want to make.
If you’re only looking to provide documentation of the birds you find, a smartphone may be
sufficient, but if you plan to record frequently, or are interested in documenting natural history
and bird behavior, it’s probably worth investing in a shotgun microphone, or even a parabola.