Sound Capture - Directional polar patterns

Learning Outcomes

• Define a microphone polar pattern and explain how it relates to direction of sound pickup.
• Describe the main features of cardioid, figure-of-8, supercardioid and hypercardioid patterns.
• Explain how polar pattern choice affects spill, room sound, feedback risk and stereo recording.
• Identify suitable polar patterns for common studio and live sound capture tasks.
• Recognise exam clues that point to a particular polar pattern or microphone placement issue.
• Use accurate technical vocabulary when discussing directional microphone behaviour.

Edexcel A-Level Music Technology (9MT0) Syllabus

In Component 3: Listening and Analysing, you need to understand how music technology equipment is used and how sound capture choices affect recorded sound. Directional polar patterns are part of this because the direction from which a microphone accepts or rejects sound has a direct effect on clarity, ambience, spill, stereo image and the suitability of a microphone for a recording situation.

• Know that a polar pattern describes direction of pickup, not whether a microphone is dynamic or condenser.
• Recognise common patterns such as cardioid and figure-of-8.
• Explain how rear rejection, side rejection and pickup angle affect recorded sound.
• Link polar pattern choice to close miking, ambient miking and unwanted spill.
• Understand why cardioid microphones are common in both studio and live work.
• Explain why figure-of-8 microphones are useful in some stereo and isolation techniques but can capture rear sound.
• Apply polar pattern knowledge to exam questions about microphone choice, room sound and recording problems.

Test Your Knowledge

Attempt these questions before reading this article. If you find some difficult or cannot remember the answers, look more closely at that area during your revision.

1. What does a microphone polar pattern show?
2. Why is a cardioid microphone often chosen for live vocals or close studio recording?
3. What is the main difference between cardioid and figure-of-8 pickup?
4. How can a directional polar pattern reduce the amount of room reverb captured?
5. Why might a figure-of-8 microphone be a poor choice if there is unwanted sound behind it?

Introduction

A microphone does not always pick up sound equally from every direction. Some microphones mainly capture sound from the front, some capture from both front and back, and some are designed to be almost equally sensitive all around. This directional behaviour is called the microphone’s polar pattern. It is one of the most important sound capture choices because it affects how direct, clean, spacious or noisy a recording becomes.

For Edexcel A-Level Music Technology, you should be able to go beyond naming a pattern. You need to explain the impact on the sound: whether the microphone will reject spill from other instruments, whether it will capture room ambience, whether it is suitable for a live stage, and whether it could cause problems if used in the wrong position.

Key Term: polar pattern
The directional pickup response of a microphone, showing how sensitive it is to sound arriving from different angles.

What a polar pattern tells you

A polar pattern is usually shown as a circular diagram viewed from above the microphone. The front of the microphone is normally shown at 0 degrees, the rear at 180 degrees, and the sides at 90 and 270 degrees. The shape on the diagram shows how strongly the microphone picks up sound from each direction.

This is not the same thing as microphone type. A dynamic microphone can have a cardioid polar pattern, and a condenser microphone can also have a cardioid polar pattern. Some condenser microphones have a switch allowing different polar patterns, such as cardioid, omnidirectional and figure-of-8. The pattern describes directionality; the microphone type describes how the microphone converts sound energy into an electrical signal.

Key Term: directionality
The extent to which a microphone favours sound arriving from particular directions.

Directional polar patterns are used to control what the microphone hears. If you point a cardioid microphone at a singer, it captures the singer strongly from the front while reducing sound arriving from the rear. In a studio this can reduce headphone spill, instrument bleed and room reflections. In live sound it can help reduce feedback because the microphone can be aimed away from monitor speakers.

The pattern also affects the amount of natural reverb captured. Close miking already increases the proportion of direct sound compared with room sound, but a directional pattern can reduce room pickup further, especially from the rear and sides. This is why cardioid microphones often give a drier, more focused sound than less directional approaches.

Test Tip: If an exam question asks about the “impact” of a polar pattern, do not only name the pattern. Explain the result: less spill, more isolation, more room sound, stronger front pickup, rear rejection, or possible feedback reduction.

A polar pattern is not perfectly fixed at all frequencies. In real microphones, directionality can change across the frequency range. Low frequencies are often less directional than high frequencies, and off-axis sounds may be coloured rather than simply made quieter. This means a sound arriving from the side may be quieter and duller, not just lower in level.

Key Term: off-axis
Describes sound arriving at a microphone from an angle away from the main front pickup direction.

Off-axis sound matters in ensemble recording. For example, if a cardioid vocal microphone is aimed at a singer but also picks up cymbals from the side, the cymbals may sound thin or uneven because they are not arriving on-axis. In an exam answer, this can help you explain why poor microphone positioning may produce spill that is not only too loud but also tonally poor.

Cardioid pickup and rear rejection

Cardioid is the most common directional polar pattern. Its name comes from its heart-like shape. A cardioid microphone has strong pickup from the front, reduced pickup from the sides and minimal pickup from the rear. This makes it useful for both studio and live recording because it is directional enough to focus on a source while rejecting some unwanted sound.

Key Term: cardioid
A heart-shaped polar pattern with strong front pickup, reduced side pickup and low rear pickup.

A cardioid microphone is often a good choice for lead vocals. In a studio, the singer performs into the front of the microphone. Sound from behind the microphone, such as room reflections or computer fan noise, is reduced. If the singer is close to the microphone, the recorded vocal will usually be direct and present, with less natural ambience than a more open or distant technique.

Cardioid is also common for guitar amps. A dynamic cardioid microphone placed close to a loudspeaker cone captures a focused sound while reducing spill from drums or other instruments in the room. On snare drum, a cardioid dynamic microphone can be angled to capture the drum while reducing hi-hat spill by placing the hi-hat closer to the microphone’s rejection area.

In live sound, cardioid vocal microphones are very common because the rear rejection can be used to reduce feedback. A stage monitor can be placed behind the microphone, where the cardioid pattern is least sensitive. This does not remove feedback risk entirely, but it gives the engineer more control.

Key Term: rear rejection
The reduction of sound pickup from the back of a directional microphone.

Cardioid microphones also tend to capture less room reverb than microphones with wider pickup. This links directly to sound capture and listening analysis. A close cardioid vocal is likely to sound dry, intimate and clear, while a more distant or less directional capture may sound more ambient.

Exam Warning: Do not write that cardioid microphones “only” pick up sound from the front. They still pick up some sound from the sides and sometimes a little from the rear. The key point is reduced pickup, not total silence.

Directional microphones such as cardioids can also show proximity effect. This is a bass boost that happens when the source is very close to the microphone. It can make a vocal sound warm and full, but too much can make it boomy or muddy. Many radio vocal recordings use this effect deliberately, while engineers may use a pop shield and careful distance control to avoid excessive bass.

Key Term: proximity effect
The increase in low-frequency response that can occur when a source is very close to a directional microphone.

For exam answers, proximity effect is useful when describing why a close vocal sounds bass-heavy or intimate. However, do not confuse proximity effect with EQ. EQ may be used later in production, but proximity effect is caused during sound capture by the interaction between the source distance and the microphone’s directional design.

Figure-of-8 pickup and side rejection

A figure-of-8 microphone picks up sound from the front and rear while rejecting sound from the sides. Its polar diagram looks like two loops, one in front of the microphone and one behind it. This pattern is common on ribbon microphones and on many multi-pattern condenser microphones.

Key Term: figure-of-8
A polar pattern that captures sound from the front and rear of the microphone while rejecting sound from the sides.

The main strength of figure-of-8 is its strong side rejection. If unwanted sound is coming from the sides, a figure-of-8 microphone can be positioned so that the side nulls face the unwanted source. This can be useful when recording two singers facing each other with one microphone, or when trying to reduce spill from instruments positioned to the sides.

Key Term: null point
The angle of a polar pattern where the microphone has its lowest sensitivity to incoming sound.

However, the rear pickup is just as important as the front pickup. A figure-of-8 microphone does not reject sound behind it. If the rear of the microphone faces a reflective wall, a noisy performer, a loud drum kit or an audience, it will capture that sound. This can be useful or harmful depending on the task.

For example, a figure-of-8 condenser placed in front of an acoustic guitar will capture the guitar from the front and some room sound from the rear. In a good room, this may add natural ambience. In a poor room, it may make the recording boxy or uncontrolled. In the exam, a suitable answer should connect the polar pattern to the acoustic result, not treat the pattern as an isolated fact.

Figure-of-8 patterns are also central to some stereo recording techniques. In mid-side recording, a cardioid or other forward-facing “mid” microphone is combined with a sideways-facing figure-of-8 “side” microphone. The figure-of-8 captures left-right difference information. In Blumlein stereo, two figure-of-8 microphones are placed at 90 degrees to each other, creating a realistic stereo image in a suitable acoustic space.

Key Term: mid-side recording
A stereo microphone technique using a forward-facing mid microphone and a sideways-facing figure-of-8 side microphone.

Key Term: Blumlein pair
A stereo technique using two figure-of-8 microphones crossed at 90 degrees to capture a natural stereo image.

Figure-of-8 microphones usually have strong proximity effect, so close vocals can sound very full. This can be attractive for some voices but may require distance control or low-frequency EQ. They also tend to be more sensitive to placement errors because sound from both the front and rear affects the result.

Test Tip: If a question says a microphone captures equally from front and back but rejects the sides, the answer is figure-of-8, not omnidirectional. Omnidirectional pickup is all around; figure-of-8 has side nulls.

Supercardioid, hypercardioid and practical microphone choice

Cardioid and figure-of-8 are the key patterns you are most likely to meet, but you should also understand narrower directional patterns. Supercardioid and hypercardioid microphones have a tighter front pickup than cardioid, meaning they focus more strongly on sound arriving from the front. They also have a small rear pickup lobe, so their rejection is not directly behind the microphone in the same way as standard cardioid.

Key Term: supercardioid
A directional polar pattern with a narrower front pickup than cardioid and a small amount of rear pickup.

Key Term: hypercardioid
A very directional polar pattern with a tighter front pickup than supercardioid and a more noticeable rear pickup lobe.

These patterns can be useful when greater isolation is needed. For example, a supercardioid microphone on a loud stage can help focus on a vocalist while rejecting more side spill than cardioid. A hypercardioid microphone may be used when a source needs to be isolated from nearby sounds, such as in film dialogue recording or difficult live situations.

The trade-off is that the rear lobe must be managed. With a cardioid microphone, a monitor speaker is often placed behind the microphone. With supercardioid or hypercardioid patterns, placing a monitor directly behind the microphone may feed sound into the rear lobe. Instead, monitors are often placed slightly off to the rear sides, aligned with the pattern’s rejection angles.

This is a common exam trap: narrower does not always mean simpler. A more directional microphone can reject side spill, but it may also pick up sound from the rear. If the rear lobe faces an unwanted source, the recording can still suffer from spill or feedback.

Exam Warning: Avoid saying that hypercardioid is “best” because it is most directional. The best pattern depends on the source, room, monitor position, spill sources and desired sound.

Polar pattern choice is closely linked to microphone placement. A cardioid microphone placed badly may capture more spill than a figure-of-8 microphone placed well. Equally, an omnidirectional microphone in a good acoustic space may sound more natural than a badly placed directional microphone. In exam responses, always connect the pattern to the situation.

For a solo vocal in a typical home or school studio, a cardioid condenser is often suitable because it gives detailed capture with useful rejection of room sound. For a loud guitar cabinet, a cardioid dynamic microphone is common because it can handle high sound pressure levels and gives focused pickup. For drum overheads, cardioid condensers can reduce unwanted room sound, while an omnidirectional or wider pattern may be chosen if the room sounds good. For an interview with two people facing each other, a figure-of-8 microphone can work well because it captures both speakers while rejecting side noise.

Key Term: spill
Unwanted sound from other instruments or sources being picked up by a microphone.

The pattern also influences how much artificial processing may be needed later. A close cardioid capture with little room sound can be treated with reverb in the mix, giving the engineer control over the space. A recording with too much natural room sound cannot easily be made dry afterwards. This links to the wider recording principle that some sound capture choices are difficult to reverse.

When listening, clues to polar pattern are indirect. You cannot usually identify a polar pattern with certainty from audio alone, but you can infer likely choices. A very dry, close vocal with little room sound may suggest close cardioid capture. A vocal with strong room tone or sound from behind the microphone may suggest a less controlled pattern, greater distance, or a figure-of-8/omnidirectional capture. A live vocal with good isolation from stage sound may suggest a directional handheld microphone.

In written answers, use cause and effect:

• “A cardioid pattern would reduce pickup from the rear, so it would help isolate the singer from the room and other instruments.”
• “A figure-of-8 microphone would capture sound from both front and rear, so it may add room ambience if the rear faces the room.”
• “A supercardioid microphone would give tighter front pickup, but the engineer must avoid placing a monitor in the rear pickup lobe.”
• “The side nulls of a figure-of-8 microphone could be aimed at unwanted spill sources.”

These sentences are stronger than simply listing pattern names because they show that you understand the effect on the recording.

Applying polar patterns in exam-style situations

Polar pattern questions often test practical judgement. You may be given a recording problem and asked to suggest a suitable microphone setup. The safest method is to identify the desired sound, the unwanted sound, then choose a pattern that supports the goal.

Question: A singer is recording in the same room as an acoustic guitarist. The vocal microphone is picking up too much guitar spill. What could be done?

A good answer could be: use a cardioid microphone for the vocal and aim the front at the singer while placing the guitar nearer the rear rejection area. If using a figure-of-8 microphone, aim one of the side nulls towards the guitar. The singer may also be moved closer to the microphone, using a pop shield and controlled distance, to increase the direct vocal level compared with the spill.

Question: A vocal recording sounds very roomy and distant. What polar pattern choice could help?

A suitable answer could be: a cardioid microphone placed closer to the singer would capture more direct sound and less room ambience because it has reduced pickup from the sides and rear. This would usually give a drier, clearer vocal sound.

Question: A figure-of-8 microphone is used for a singer, but the recording contains loud reflections from the back wall. Why?

The rear lobe of the figure-of-8 pattern is capturing sound behind the microphone. If the back of the microphone faces a reflective wall, rear pickup may capture reflections, increasing room sound.

For Edexcel listening and analysing work, the quality of your explanation matters. Use precise words such as front pickup, rear rejection, side nulls, spill, room ambience, proximity effect and off-axis colouration. These show technical understanding and help you gain credit in short and extended responses.

Key Point Checklist

This article has covered the following key knowledge points:

• A polar pattern shows the directions from which a microphone picks up sound.
• Polar pattern is not the same as microphone type; dynamic and condenser microphones can share the same pattern.
• Cardioid microphones pick up mainly from the front, less from the sides and very little from the rear.
• Cardioid is common in studio and live work because it gives useful isolation and rear rejection.
• Directional microphones usually capture less room sound than wider patterns when used close to the source.
• Figure-of-8 microphones pick up from the front and rear while rejecting the sides.
• Figure-of-8 side nulls can be useful for reducing spill from sources placed to the sides.
• Figure-of-8 microphones can capture unwanted rear sound if positioned badly.
• Supercardioid and hypercardioid patterns have tighter front pickup but include rear pickup lobes.
• Proximity effect can increase bass when a source is very close to a directional microphone.
• Off-axis sound may be quieter and tonally coloured, not simply reduced in level.
• Exam answers should link polar pattern choice to practical effects such as clarity, spill, feedback and ambience.

Key Terms and Concepts

• polar pattern
• directionality
• off-axis
• cardioid
• rear rejection
• proximity effect
• figure-of-8
• null point
• mid-side recording
• Blumlein pair
• supercardioid
• hypercardioid
• spill