Microphone Pickup Patterns

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microphone, pick-up patterns.

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Choosing

and using the right mic for
the job is an important step in any video

project and understanding of microphones'
directional characteristics

is one determining factor.

In this segment we talk about
a microphone's directional response

and sensitivity.

How to interpret a polar response chart.

And we listen to examples of various mics
to hear how directional response

works in practice.

Knowing how to determine
the directional characteristics of a mic

and understanding how this affects
the sound your mic picks up

can help you make an informed
choice for your next project.

All microphones aren't created equal.

And one key characteristic of every mic
is its directional response,

sometimes referred to as a polar
or pickup pattern.

A microphone's directional response
determines how it responds

to sounds coming into the mic
from different directions.

A polar response
chart is a standardized way

of displaying a microphone's
directional characteristics.

To determine a mix polar pattern.

Manufacturers
play various frequencies aimed directly

at the mic in an anechoic chamber
and then rotate the mic

360 degrees to measure the sensitivity
of a mic at those frequencies.

The sensitivity of the mic refers
to how much sound output

it gives compared to the amount of sound
input it receives.

Mics with higher sensitivity
to a specific frequency will reproduce it

with a strong output signal,
while mics with a lower sensitivity

to a frequency, will reproduce the sound
at a much lower output level.

Microphones often respond
quite differently to various frequencies,

and a polar response
chart is a great way to see this.

Beginning in the center
ring moving outward, each step

typically represents
five DB of sensitivity.

The innermost ring represents
low sensitivity,

while the outermost ring represents
high sensitivity.

The straight lines on the diagram
represent the direction of incoming sound.

Zero degrees represents
sound heading straight into the diaphragm

of a given mic.

90 degrees and 270 degrees represent sound
coming into the side of the mic

and 180 degrees represents sound
coming into the back of the mic diaphragm.

It's important

to understand that while this is displayed
as a two dimensional graph,

it actually represents
a three dimensional pickup pattern.

There are two broad categories
that most mics fall into.

Omni-directional and directional.

Omni-directional
mics are designed to be equally sensitive

to sound, regardless of which direction
sound comes from.

Of course, in reality,

they don't pick up all frequencies
equally from all directions.

Omni-directional mics are great
for picking up groups of people

or an overall room sound, but
can't be aimed for selective sound pickup.

This is the polar pattern for the DPA
EMK 4071,

which is an omni-directional, lavalier
microphone.

You can see that while the response does
vary a bit depending on the frequency,

it is still very sensitive
to sound coming from all directions.

Let's see this mic in action.

In this setup,

we're starting with the mic diaphragm
facing directly toward our speaker.

Now let's turn
the microphone. 360 degrees.

You can hear that there

was little to no falloff
as the mic direction changed.

Unlike omni-directional mics, directional
mics are designed

to be more sensitive
to sound coming from specific directions.

The most common patterns
that fall under this category

are bi-directional cardioid,

hyper-cardioid, super-cardioid and lobar.

Let's take a look at each one.

A bi-directional pickup
pattern is sometimes referred to

as a figure-eight pattern.

These mics are designed to pick up
audio from the front and back of the mic

while rejecting sound from the sides.

This is the pattern for the Shure KSM 353.

You can see that the mic picks up sound

equally from the front
and back of the diaphragm.

These mics are most commonly used
to record musical instruments.

The Cardioid pickup pattern got its name
from its heart shaped appearance.

It's designed to pick up sound

from the front of the diaphragm
and reject sound from the back.

This is the polar pattern
for the Shure SM7A.

You can see that the cardioid pattern
picks up mostly from the front of the mic

while rejecting
most of the sound from the back and sides.

Notice that this is a bit more sensitive
to some lower frequencies from the back.

Let's take a listen.

Just as

the polar pattern indicated,
you heard a significant output

falloff as we turned toward the side
and back of the mic.

A hyper-cardioid pickup pattern is a more
directional version of the cardioid.

The main difference is that it
rejects more audio from the side,

but also picks up
a little more directly in the rear.

These mics are sometimes referred to
as mini shotguns.

This is the polar pattern for the Audio
Technica 4053B.

If we compare its polar
pattern to the SM7A,

you can see that the sensitivity
from the back side in this area is reduced

while the area directly behind
the mic is more sensitive.

mics with super cardioid patterns
are similar to hyper-cardioid, but

have even more picked up from the front
and less pick up from the back.

Some super-cardioid mics
use interference tubes that use

phase cancelation
to eliminate more sound from the sides.

These are often referred to as shotgun
or line and gradient mics.

Because of their narrow pickup,

they require even more accurate
positioning to pick up the desired sound.

They can also be further away
from the source and still capture

good sound, making them extremely useful
for use in many video projects.

This is the polar pattern of the Rode
NTG-2 Shotgun Mic.

You can see that
the side rejection is significant, but

the sensitivity from the back
is also more pronounced.

The difference between the SM7A
cardioid pattern is very pronounced.

Let's take a listen.

It's clear that this
mic has a very narrow pickup in the front,

as well as slightly
increased sensitivity from the back.

When you want the extreme and microphone
directionality, you've got the lobar

pickup pattern.

This pattern is only achievable in shotgun
microphones.

These mics have long interference tubes
to cancel out the sound from the sides.

This is the polar pattern for the DPA
MMC 4017.

Notice how widely the pickup ranges,
depending on the frequency.

Let's take a listen.

It's easy to understand why

it takes a skilled audio operator
to capture great sound with this mic.

Getting great sound is a crucial component
of high quality video

production, and choosing the right mic for
the job can be a tough one.

Understanding how a pickup pattern affects
a mic's ability to capture

sound in different situations can help
you make the right decision

for your next
project. Thanks for watching.