How do microphones convert sound into a signal, and how do their type and polar pattern affect what they capture?
Microphone types (dynamic, condenser, ribbon) and how each transduces sound, polar patterns (cardioid, omnidirectional, figure-of-eight, hyper-cardioid), and how type and pattern govern frequency response, sensitivity and rejection.
A focused answer to the Edexcel 9MT0 microphone content, covering dynamic, condenser and ribbon microphones, how each works, polar patterns (cardioid, omnidirectional, figure-of-eight), and how type and pattern affect frequency response and rejection.
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What this dot point is asking
Edexcel wants you to know the three microphone families, how each converts sound into a signal, and the polar patterns that describe their directionality. You must be able to choose a microphone for a given source and justify it technically, and explain how type and pattern affect frequency response, sensitivity and the rejection of unwanted sound. This is core knowledge for both the Component 1 recording and the analysis papers.
The answer
Microphones as transducers
The choice of microphone shapes the recorded tone before any processing, so it is the first and one of the most important production decisions. Type affects sensitivity, frequency response and how much sound pressure the mic can handle; pattern affects what it picks up and what it rejects.
Dynamic microphones
Condenser microphones
Ribbon microphones
Polar patterns
Pattern choice controls spill and room sound. A cardioid rejects the drum kit behind it; an omni captures the room as well as the source; a figure-of-eight is the basis of Mid-Side stereo and can reject sound to the sides. Directional mics also show the proximity effect, a bass boost when placed close to the source.
Examples in context
When you reach for a dynamic mic on a snare and a condenser on the overheads, you are matching ruggedness and detail to each source. When you switch a vocal mic to cardioid in an untreated room, you are using rear rejection to keep reflections out of the recording. When you set up a figure-of-eight as the side mic in a Mid-Side pair, you are exploiting its pattern to capture stereo width. Microphone choice is where the recording's character begins.
Try this
Q1. State how a dynamic microphone converts sound into a signal. [1 mark]
- Cue. By electromagnetic induction: a coil on the diaphragm moves in a magnetic field.
Q2. Which microphone type needs phantom power, and why? [2 marks]
- Cue. The condenser, because it works as a capacitor whose diaphragm and backplate must be charged.
Q3. Name the polar pattern that picks up from the front and rear but rejects the sides. [1 mark]
- Cue. Figure-of-eight (bidirectional).
Exam-style practice questions
Practice questions written in the style of Pearson Edexcel exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
Edexcel 9MT0/03 20184 marksA producer is choosing a microphone to record a loud snare drum and, separately, a delicate acoustic guitar. Recommend a microphone type for each, and justify each choice with reference to how the microphone works.Show worked answer →
For the loud snare drum, recommend a dynamic microphone. A dynamic mic works by electromagnetic induction (a coil attached to the diaphragm moves in a magnetic field), making it rugged and able to handle very high sound pressure levels without distorting; its slightly limited high-frequency response also suits a percussive, transient-heavy source.
For the delicate acoustic guitar, recommend a condenser microphone. A condenser works as a capacitor (a charged thin diaphragm and backplate whose changing spacing varies the capacitance), giving high sensitivity and an extended, detailed high-frequency response that captures the string and body detail of an acoustic instrument. It needs phantom power and is more fragile.
Markers reward dynamic for the snare (rugged, high SPL, induction), condenser for the guitar (sensitive, detailed highs, capacitor, phantom power), with the working principle stated for each.
Edexcel 9MT0/03 20214 marksExplain the difference between a cardioid and an omnidirectional polar pattern, and describe one recording situation where each would be the better choice.Show worked answer →
A cardioid pattern is most sensitive to sound arriving from the front and rejects sound from the rear, giving a heart-shaped pickup. An omnidirectional pattern is equally sensitive in all directions.
A cardioid is the better choice when you need to isolate one source and reject spill, for example close-miking a single instrument on a loud stage or in an untreated room, because the rear rejection cuts unwanted bleed and room sound. An omnidirectional is the better choice when you want a natural, open capture of an instrument together with the room, for example a single mic on an acoustic ensemble in a good-sounding space, because it has a flatter frequency response, less proximity effect and captures the ambience evenly.
Markers reward cardioid = front pickup with rear rejection, omni = equal in all directions, plus a sensible matched scenario for each.
Related dot points
- Microphone placement: close, distant and ambient miking, the proximity effect, off-axis placement, and stereo techniques (spaced pair AB, coincident XY, ORTF, Mid-Side) and how each creates a stereo image.
A focused answer to the Edexcel 9MT0 placement content, covering close, distant and ambient miking, the proximity effect, off-axis placement, and stereo techniques (spaced pair, XY, ORTF, Mid-Side) and the image each produces.
- The recording signal chain: microphone, mic preamp and gain, line and mic level, the A/D converter and audio interface, balanced and unbalanced connections, and gain staging to optimise the signal-to-noise ratio and avoid clipping.
A focused answer to the Edexcel 9MT0 signal chain content, covering microphone, preamp and gain, mic and line level, the A/D converter and interface, balanced connections, and gain staging for signal-to-noise and headroom.
- Capturing and editing audio: setting levels and recording cleanly, non-destructive editing, cutting, trimming and moving regions, comping the best take, crossfades to avoid clicks, fades, and removing noises and breaths.
A focused answer to the Edexcel 9MT0 capture and editing content, covering recording cleanly, non-destructive editing, cutting and moving regions, comping, crossfades, fades, and removing noises.
- Sound as a longitudinal pressure wave: amplitude and loudness, frequency and pitch, period, wavelength and the wave equation, and the audible frequency range.
A focused answer to the Edexcel 9MT0 principles of sound, covering sound as a longitudinal pressure wave, amplitude and loudness, frequency and pitch, period, wavelength, the wave equation and the audible range.
- The mixing process: setting levels and the static balance, frequency balance and avoiding masking, the three dimensions of a mix (level, frequency, stereo), creating depth, bus routing and submixing, and the goal of a clear, balanced mixdown.
A focused answer to the Edexcel 9MT0 mixing content, covering setting levels and the static balance, frequency balance and masking, the three dimensions of a mix, creating depth, bus routing and the mixdown.
Sources & how we know this
- Pearson Edexcel A-Level Music Technology (9MT0) specification — Pearson Edexcel (2017)