Sound Capture - Directional microphones

Learning Outcomes

• Explain what a microphone polar pattern is and how it affects sound capture.
• Describe cardioid, supercardioid, hypercardioid and figure-of-8 pickup patterns.
• Choose suitable directional microphones for vocals, drums, guitar amps, acoustic instruments and ensemble recording.
• Explain how directional microphones affect spill, room sound, feedback risk and isolation.
• Recognise common recording problems caused by poor microphone angle or placement.
• Use exam-ready vocabulary when evaluating microphone choices in Component 1 recording work.

Edexcel A-Level Music Technology (9MT0) Syllabus

In Component 1: Recording, you are expected to show that you can capture musical instruments accurately using suitable music technology equipment. Directional microphones are central to this because the microphone’s pickup pattern affects tone, isolation, spill, room ambience and the balance between direct and reflected sound.

• Select appropriate microphone polar patterns for different instruments and recording contexts.
• Understand that polar pattern is not the same thing as microphone type: dynamic, condenser and ribbon microphones can have directional characteristics.
• Explain why cardioid microphones are common in studio and live recording.
• Use directional microphones to reduce unwanted sound from other instruments or the room.
• Recognise the uses and risks of figure-of-8 microphones, including side rejection and rear pickup.
• Discuss close miking, ambient miking and the amount of room sound captured.
• Evaluate how microphone placement affects the quality of a recorded performance.
• Refer accurately to spill, off-axis sound, proximity effect and rear rejection in written explanations.

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 is a polar pattern, and why does it matter when recording a band in the same room?
2. Why is a cardioid microphone often chosen for vocals or guitar amplifiers?
3. How does a figure-of-8 microphone pick up sound, and where are its rejection points?
4. What is proximity effect, and why might it be a problem when close miking a singer?
5. Why can a condenser microphone with a pad switch be useful when recording a loud source?

Introduction

Directional microphones allow an engineer to control not only what is recorded, but also what is rejected. In a recording task, the difference between a clear, controlled vocal and a muddy vocal with too much drum spill may be as simple as choosing the right polar pattern and aiming the microphone correctly. Directionality is therefore a practical sound-capture tool, not just a technical term to memorise.

A microphone’s directionality is described by its polar pattern. This tells you where the microphone is most sensitive and where it rejects sound. In Component 1, this knowledge helps you make better recording decisions: placing a cardioid dynamic microphone close to a guitar amplifier, using condensers as drum overheads, choosing a figure-of-8 setting for a specific stereo technique, or reducing room reflections by changing the microphone angle.

Key Term: directional microphone
A microphone that is more sensitive to sound from some directions than others, allowing the engineer to favour the intended source and reduce unwanted sound.

Key Term: polar pattern
The directional pickup shape of a microphone, showing where it captures sound most strongly and where it rejects sound.

Polar patterns and microphone directionality

All microphones have a polar pattern. This is not a separate category of microphone like “dynamic” or “condenser”; it is the directional behaviour of the microphone. A dynamic vocal microphone, a small-diaphragm condenser and a large-diaphragm condenser may all be cardioid, even though they use different methods to convert sound into an electrical signal.

The key practical question is: from which direction will this microphone capture sound best? If the answer is “mostly from the front”, the microphone can be used to focus on one source. If the answer is “front and rear”, it may be useful in some specialist situations but risky in a crowded room. If the answer is “all around”, it is not directional and will capture more ambience and spill.

A polar pattern is often drawn as a circular graph around the microphone. The front of the microphone is usually shown at 0 degrees. The rear is 180 degrees. The sides are 90 and 270 degrees. A directional microphone will show stronger pickup in some areas and weaker pickup in others.

Key Term: off-axis rejection
The reduction in level of sounds arriving from outside the microphone’s main pickup direction.

Directional microphones are useful because they help control three major aspects of sound capture:

• Isolation: focusing on one source and reducing other instruments.
• Room sound: capturing less reflected sound from walls, floor and ceiling.
• Feedback control: in live sound, rejecting loudspeaker sound to reduce the risk of feedback.

In studio coursework, isolation is often the main issue. For example, if a singer is recording guide vocals in the same room as an acoustic guitarist, a cardioid microphone can be aimed at the singer with its least sensitive area facing the guitar. This will not remove spill completely, but it can reduce it enough to make mixing easier.

Directional microphones also affect tone. Sound arriving from the side or rear of a microphone may be quieter, but it can also be coloured. Off-axis sound is often less natural than direct sound. This matters when recording instruments with wide frequency ranges, such as piano, drum kit or acoustic guitar, because reflections and spill may not sound neutral.

Exam Warning: Do not write that “a condenser microphone is directional” as if all condensers behave the same way. Condenser describes the microphone’s operating principle. Cardioid, figure-of-8 and omnidirectional describe pickup pattern.

Cardioid, supercardioid and hypercardioid microphones

The cardioid polar pattern is the most common directional pattern in recording. The name comes from its heart-like shape. A cardioid microphone has strong pickup at the front, reduced pickup at the sides and very little pickup from the rear. This rear rejection makes it useful in both studio and live work.

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

Cardioid microphones are widely used because they give a practical balance between focus and naturalness. They are directional enough to reduce unwanted sound, but not so narrow that they become difficult to aim. A cardioid microphone can be a good choice for:

• lead vocals
• backing vocals
• guitar amplifiers
• snare drum
• toms
• brass instruments
• acoustic guitar
• percussion
• podcast-style speech recording

For vocals, a cardioid microphone helps reduce room sound and other instruments. For guitar amplifiers, a cardioid dynamic microphone placed close to the speaker cone can give a focused sound with strong isolation. For snare drum, a cardioid dynamic microphone can be angled to reduce hi-hat spill.

The main practical skill is aiming the rejection area. With a cardioid microphone, the rear of the microphone is the area of greatest rejection. If you are recording a vocalist while a loud drummer is nearby, place the microphone so that the back of the mic points as much as possible towards the drums. If you are recording snare, angle the rear of the microphone towards the hi-hat to reduce spill.

Key Term: spill
Unwanted sound from one instrument or source being captured by a microphone intended for another source.

Supercardioid and hypercardioid patterns are more directional than cardioid. They have a narrower front pickup area, which can give greater isolation from sounds at the sides. However, they also have a small rear pickup area, known as a rear lobe. This means they do not simply reject everything behind them.

Key Term: rear lobe
A smaller area of sensitivity at the back of some highly directional microphones, especially supercardioid and hypercardioid designs.

A supercardioid microphone can be useful when you need more separation than cardioid provides. For example, a singer on a loud stage may use a supercardioid microphone to reduce spill from instruments at the sides. In the studio, a hypercardioid microphone might help focus on a drum or amplifier in a difficult room. The trade-off is that placement becomes more critical. If a loud source is directly behind a supercardioid or hypercardioid microphone, the rear lobe may pick it up.

Test Tip: In an exam answer, link the polar pattern to the recording result. For example: “A cardioid dynamic microphone would suit the guitar amp because it captures mainly from the front and rejects sound from the rear, reducing spill from the drum kit.”

Directional patterns are also affected by frequency. Many microphones become less directional at low frequencies and more directional at high frequencies. This means a microphone may reject high-frequency hi-hat spill better than low-frequency bass spill. For A-Level answers, you do not usually need deep physics, but you should avoid claiming that rejection is perfect. Directionality reduces unwanted sound; it does not remove it.

Figure-of-8 and multi-pattern microphones

A figure-of-8 microphone picks up sound from the front and rear while rejecting sound from the sides. Its polar pattern looks like the number 8, with two lobes of sensitivity. This pattern is common on many ribbon microphones and is also available on some 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 most useful feature of a figure-of-8 microphone is its side rejection. Sounds arriving from 90 degrees and 270 degrees are strongly reduced. This can be useful when two sound sources are placed opposite each other, or when you need to reject sounds from the sides.

Examples include:

• recording two backing vocalists facing each other, one on each side of the microphone
• using a figure-of-8 microphone in Mid-Side stereo recording
• rejecting reflections from side walls by aiming the side nulls at the reflective surfaces
• recording a duet with controlled pickup from front and rear

However, figure-of-8 microphones need careful placement because they capture from the rear as well as the front. If the rear of the microphone faces a noisy computer fan, a reflective wall or another instrument, that sound may be captured strongly. This makes figure-of-8 less suitable when you simply want to reject everything behind the microphone.

A multi-pattern condenser microphone may offer cardioid, omnidirectional and figure-of-8 settings. Some also offer intermediate patterns. This flexibility is very useful in studio work. For example, the same large-diaphragm condenser could be used in cardioid for a lead vocal, figure-of-8 for a duet, and omnidirectional for a more open room sound. Many condensers need phantom power, usually supplied by a mixing desk or audio interface.

Key Term: phantom power
DC power, commonly supplied by a mixer or audio interface, required by many condenser microphones.

Condenser microphones are often chosen for detailed recording because they are more sensitive than dynamic microphones and can capture quieter sounds and fast transients well. A small-diaphragm condenser is often suitable for acoustic guitar, drum overheads or percussion because it can capture high-frequency detail clearly. A large-diaphragm condenser is often used for studio vocals because it can capture detail and presence.

Because condensers are sensitive, they can overload more easily near very loud sources. Many condenser microphones include a pad switch, often reducing the level by 10 or 20 dB before the signal reaches the microphone’s internal electronics.

Key Term: pad switch
A switch that reduces a microphone’s output level by a fixed amount, helping prevent overload when recording loud sources.

For example, a condenser used as a drum overhead may need a pad if the drummer plays loudly. A condenser in front of a brass instrument may also benefit from a pad and careful positioning. Condensers should also be protected from moisture when recording vocals or brass; a pop shield and sensible distance reduce the risk.

Exam Warning: A figure-of-8 microphone is not “more directional” in the same simple way as a cardioid. It rejects the sides very well, but it also picks up strongly from the rear. Always describe both features.

Placement, room sound and Component 1 recording choices

Directional microphone choice cannot be separated from placement. The same microphone can produce very different results depending on distance, angle and room acoustics.

Close miking places the microphone near the source. This increases the amount of direct sound compared with room reflections. It also reduces spill because the wanted source is much louder at the microphone than other sounds in the room. Close miking is common for vocals, guitar amps, drums and some acoustic instruments in pop recording.

Key Term: close miking
Placing a microphone near a sound source to capture a strong direct sound with less room ambience.

Close miking with a directional microphone can create a very controlled recording, but it can also produce problems. The most common is proximity effect.

Key Term: proximity effect
The increase in bass response that occurs when many directional microphones are placed very close to a sound source.

Proximity effect can be useful. A singer may sound warmer when close to a cardioid microphone. A radio-style voice may sound fuller because of the extra low end. However, too much proximity effect can make a vocal boomy or unclear. It can also exaggerate plosives such as “p” and “b”. A pop shield, high-pass filter, slightly increased distance or adjusted microphone angle can help.

Ambient miking places the microphone further from the source to capture more of the room. The further the microphone is from the source, the more reflected sound it captures in proportion to direct sound. This is useful in some styles, especially where the recording space sounds good. Classical recording often uses more ambient technique because the room is part of the desired sound. In a small untreated classroom or rehearsal room, however, too much ambience may make the recording boxy or unclear.

Key Term: ambient miking
Placing a microphone further from the source to capture more of the acoustic sound of the room.

A cardioid microphone captures less room sound than an omnidirectional microphone at the same distance because it rejects some sound from the sides and rear. This is one reason cardioid is a safe choice for many school or college recording spaces. If the room has poor acoustics, use directional microphones closer to the source and aim rejection areas towards reflective surfaces or unwanted instruments.

When recording an ensemble, microphone directionality helps create separation before mixing starts. This matters because spill is hard to remove afterwards. For example:

• Lead vocal: use a cardioid condenser or dynamic microphone, with a pop shield. Aim the rear away from loud instruments.
• Electric guitar amplifier: use a cardioid dynamic microphone close to the speaker grille; adjust position between centre and edge of the cone for tonal change.
• Snare drum: use a cardioid dynamic microphone angled away from the hi-hat.
• Drum overheads: use condenser microphones; cardioid patterns can reduce room reflections, while spacing and angle affect stereo image.
• Acoustic guitar: use a cardioid small-diaphragm condenser around the 12th fret area rather than directly at the sound hole, which may sound boomy.
• Piano: use a pair of condensers for stereo capture where possible; directional patterns can help control reflections and mechanical noise.

Test Tip: For Component 1 commentary or written evaluation, explain the reason for the microphone choice. “I used a cardioid condenser on acoustic guitar” is weaker than “I used a cardioid small-diaphragm condenser aimed near the 12th fret to capture detail while reducing room reflections and avoiding the boom of the sound hole.”

Directional microphones also interact with monitoring. In live recording or overdubbing with speakers, a cardioid microphone should usually have its rear rejection aimed at the loudspeaker. With supercardioid and hypercardioid microphones, the best rejection points are not always directly behind the mic because of the rear lobe. This is why stage monitor placement differs depending on microphone pattern. In studio headphone recording this is less of a feedback issue, but headphone spill can still be captured by sensitive microphones.

In exam writing, be careful with absolute claims. A cardioid microphone does not “only record the front”. It mainly captures from the front, captures less from the sides and rejects most from the rear. A figure-of-8 does not “reject the back”; it captures from the back. A condenser is not always the best choice just because it is detailed; a dynamic may be better for very loud sources or where a less sensitive microphone helps reduce spill.

Strong answers connect technical choices to audible outcomes:

• clearer vocal
• less drum spill
• reduced room ambience
• tighter drum sound
• more natural ensemble sound
• less feedback risk
• more controlled mix
• better stereo image
• less need for corrective processing later

The best recording decisions are made before pressing record. Directional microphones give you control at the capture stage, which is usually better than trying to fix problems with EQ, gating or editing afterwards.

Key Point Checklist

This article has covered the following key knowledge points:

• A polar pattern describes the direction from which a microphone captures sound.
• Directional microphone behaviour is separate from microphone type: dynamic, condenser and ribbon microphones can all be directional.
• Cardioid microphones capture mainly from the front, less from the sides and very little from the rear.
• Cardioid patterns are common for vocals, guitar amps, drums and many studio recording tasks.
• Supercardioid and hypercardioid microphones are narrower than cardioid but have a rear lobe.
• Figure-of-8 microphones capture from the front and rear while rejecting sound from the sides.
• Directional microphones help reduce spill but do not remove it completely.
• Close miking increases direct sound and reduces room ambience, but may cause proximity effect.
• Condenser microphones are sensitive and detailed, often requiring phantom power.
• A pad switch helps prevent overload when using condensers on loud sources.
• Ambient miking captures more of the room and is most useful when the room sounds good.
• Exam answers should link microphone choice and placement to the resulting sound.

Key Terms and Concepts

• directional microphone
• polar pattern
• off-axis rejection
• cardioid
• spill
• rear lobe
• supercardioid
• hypercardioid
• figure of 8
• phantom power
• pad switch
• close miking
• proximity effect
• ambient miking