Learn About Microphones

Frequency Response: The range of frequencies a microphone can capture accurately. Human hearing: 20 Hz - 20 kHz. Most mics: 50 Hz - 15 kHz is sufficient for voice.

Signal-to-Noise Ratio (SNR): The difference between your desired audio (signal) and background noise. Higher is better. 70+ dB is good, 80+ dB is excellent.

Sensitivity: How much output the mic produces for a given sound pressure. High sensitivity = louder output, picks up quiet sounds and room noise. Low sensitivity = needs more gain, but less sensitive to noise.

Maximum SPL (Sound Pressure Level): The loudest sound a mic can handle before distorting. 120 dB SPL handles normal speech/singing. 130+ dB needed for loud instruments or screaming.

Impedance: The electrical resistance of the mic. Low impedance (150-600 ohms) is professional standard, allows long cable runs. High impedance (10k+ ohms) is for short cables only.

Proximity Effect: Bass boost when closer to cardioid/directional mics. Use for "radio voice" effect or avoid by maintaining distance.

Self-Noise: The electrical noise floor generated by the microphone itself. Lower is better. Under 15 dBA is very quiet.

A polar pattern shows from which directions a microphone picks up sound.

Cardioid (heart-shaped): Picks up sound from the front, rejects from the rear. Most common pattern. Great for isolating a single source and reducing room noise. Ideal for vocals, podcasting, streaming.

Omnidirectional (all directions): Picks up sound equally from all directions. Natural sound, captures room ambience. Good for recording groups, room tone, or natural acoustic spaces.

Bidirectional/Figure-8: Picks up from front and rear, rejects from sides. Perfect for two-person interviews, recording a sound and its room reflection, or mid-side stereo recording.

Supercardioid/Hypercardioid: Tighter pickup than cardioid with small rear lobe. Better rejection of room noise and side sounds. Common in broadcast and live sound.

Choosing the right pattern reduces unwanted noise and improves recording quality.

A microphone is a transducer that converts sound waves (acoustic energy) into electrical signals. When you speak or make sound, air molecules vibrate creating pressure waves. The microphone's diaphragm moves in response to these pressure changes, and this movement is converted into an electrical signal that can be recorded, amplified, or transmitted.

The basic principle applies to all microphones, though the method of conversion varies by type. Understanding how your microphone works helps you get better sound quality.

A microphone is a device that converts sound waves into electrical signals. It works by using a diaphragm that vibrates when sound waves hit it, and these vibrations are converted into an electrical signal that can be amplified, recorded, or transmitted.

Sample rate is how many times per second audio is measured. Common rates are 44.1kHz (CD quality), 48kHz (video standard), and 96kHz (high-resolution). Higher sample rates capture more detail but create larger files. For most uses, 48kHz is excellent.

Dynamic Microphones use a diaphragm attached to a coil of wire suspended in a magnetic field. Sound waves move the diaphragm and coil, generating electrical current. They are rugged, don't need power, and handle loud sounds well. Great for live performances, podcasting, and drums.

Condenser Microphones use a thin conductive diaphragm placed close to a metal backplate, forming a capacitor. Sound waves change the distance between the plates, varying capacitance and creating an electrical signal. They require phantom power (48V), are more sensitive, capture more detail, and are ideal for studio vocals, acoustic instruments, and high-quality recordings.

Choose dynamic for durability and loud sources, condenser for detail and quiet sources.

USB Microphones have a built-in analog-to-digital converter and preamp. They plug directly into your computer's USB port and are immediately recognized. Perfect for podcasting, streaming, video calls, and home recording. They're simple, affordable, and portable. However, they're limited to one mic per USB port and have less upgrade potential.

XLR Microphones are professional analog microphones that require an audio interface or mixer. The XLR connection is balanced (reducing interference) and provides better sound quality, more flexibility, and professional features. You can use multiple mics simultaneously, upgrade your preamps separately, and have more control over your audio chain. They're standard in professional studios, live sound, and broadcast.

Beginners: Start with USB. Professionals or serious hobbyists: Invest in XLR.

Dynamic microphones use electromagnetic induction to convert sound into electrical signals. They are durable, handle high sound pressure levels well, and do not require external power. Commonly used for live performances and recording loud instruments.

Condenser microphones use a capacitor (condenser) to convert acoustic energy into electrical energy. They require phantom power (usually 48V) and are more sensitive than dynamic mics, making them ideal for studio recording vocals and acoustic instruments.

Proper microphone placement dramatically improves sound quality:

Distance: 6-12 inches for speaking, 12-24 inches for singing. Closer = more bass (proximity effect), more mouth sounds. Further = more natural, but picks up room noise.

Angle: Slightly off-axis (pointing at your mouth but not directly) reduces plosives (P and B sounds) and sibilance (S sounds).

Height: Position at mouth/nose level. Above or below changes tone.

Room treatment: Record away from walls (3+ feet) to reduce reflections. Corner placement increases bass. Use curtains, blankets, or foam to dampen reflections.

Pop filter: 2-3 inches from mic to reduce plosives without affecting tone.

Shock mount: Reduces vibrations from desk, keyboard, or floor.

Test different positions while monitoring and find what sounds best for your voice and environment.

Your recording environment matters as much as your microphone.

Room acoustics:
- Hard surfaces (walls, floors, windows) reflect sound causing echo and reverb
- Soft surfaces (curtains, carpets, furniture, blankets) absorb sound
- Ideal: Mix of absorption and diffusion for natural sound
- Problem: Parallel walls create standing waves and flutter echo

Quick improvements:
1. Record in smallest room possible (less reverb)
2. Add soft furnishings: couches, curtains, rugs, bookshelves
3. Hang moving blankets or thick curtains on walls
4. Record in a closet full of clothes (natural sound booth!)
5. Create a reflection filter behind mic using foam or blankets
6. Position yourself away from parallel walls (at least 3 feet)

Noise sources to eliminate:
- Computer fans: Move computer away, use quiet PC, or use isolation booth
- Air conditioning/heating: Turn off during recording
- Refrigerator hum: Record away from kitchen
- Traffic noise: Record during quiet hours, close windows
- Room echo: Add absorption (see above)
- Electrical interference: Keep mic away from power adapters, monitors, LED lights

Pro tip: Record a few seconds of silence to capture your "room tone" - useful for noise reduction in editing.

Budget solutions beat expensive mics in untreated rooms!

Proper microphone technique improves your sound dramatically:

Distance control:
- Normal speech: 6-10 inches
- Soft singing: 8-12 inches
- Loud singing: 10-16 inches
- Shouting/screaming: 12-24 inches

Working the proximity effect:
- Get closer for more bass/warmth (radio voice)
- Back off for more natural, balanced tone
- Use distance to add dynamics to performance

Controlling plosives (P, B, T sounds):
- Use a pop filter 2-3 inches from mic
- Position mic slightly above or to side of mouth
- Turn your head slightly during hard plosives
- Develop technique to soften plosives naturally

Reducing sibilance (harsh S sounds):
- Point mic at your mouth, not directly at center
- Position slightly below mouth aimed upward
- Back off a bit for bright/sibilant voices
- De-esser plugin in post if needed

Consistency:
- Mark your distance with tape or visual reference
- Maintain same angle and position
- Use headphones to monitor yourself
- Use shock mount to prevent handling noise

Movement:
- Stay relatively still (use shock mount for small movements)
- For music: Move closer on quiet parts, back off on loud parts
- For spoken word: Maintain consistent distance

Hand position:
- Never cup or cover the microphone (changes tone, causes feedback)
- Hold by the body, not near the grille
- For handheld: Grip firmly but don't squeeze

Practice makes perfect - record yourself and experiment!

Proper microphone placement significantly affects sound quality. For voice: position 6-12 inches from your mouth, slightly off-axis to reduce plosives. Avoid pointing directly at your mouth. Keep away from computer fans and air conditioning.

Systematic approach to diagnosing and fixing audio issues:

Problem: Thin or tinny sound
- Too far from mic or off-axis
- Wrong polar pattern selected
- Room reflections and reverb
- Fix: Move closer, position on-axis, add room treatment

Problem: Muddy or boomy sound
- Too close to mic (proximity effect)
- Poor room acoustics (bass buildup in corners)
- Fix: Back off 2-4 inches, move away from corners

Problem: Harsh or piercing sound
- Too much high frequency (sibilance)
- Mic pointed directly at mouth
- Cheap microphone without proper frequency response
- Fix: Angle mic slightly off-axis, use pop filter, EQ in post

Problem: Noisy/hissy recording
- Gain too high, boosting noise floor
- Electrical interference
- Mic preamp quality
- Fix: Reduce gain and speak louder, move away from electrical devices, upgrade interface

Problem: Muffled sound
- Too much absorption/damping
- Microphone obstructed
- Low quality mic
- Fix: Remove excessive dampening, check mic placement, upgrade equipment

Problem: Echo or reverb
- Room is too reflective
- Recording too far from mic
- Fix: Add soft furnishings, record closer, use reflection filter

Problem: Distortion
- Gain/input level too high (clipping)
- Speaking too loud/too close
- Fix: Reduce gain, back off mic, speak softer

Test systematically: Change one variable at a time, record samples, compare results.

Gain staging is the process of setting the right recording level at each point in your audio chain to maintain quality and avoid distortion.

The goal: Record as loud as possible without clipping (distorting).

Steps for proper gain staging:

1. Start with gain/input level control on interface or mixer
2. Speak or sing at your normal loudest level
3. Adjust gain so peaks hit -12 to -6 dB (yellow on meters)
4. Never let it hit 0 dB (red) - this causes digital clipping (permanent distortion)
5. If too quiet, increase gain. If clipping, decrease gain.

Why not record at maximum?
- No headroom for unexpected loud moments
- Risk of clipping
- Less flexibility in editing

Why not record too quiet?
- Must boost in editing, increasing noise floor
- Poor signal-to-noise ratio
- Loses dynamic information

Target levels:
- Speech/Podcast: -12 to -6 dB peak
- Vocals: -18 to -12 dB peak
- Music/Loud sources: -6 to -3 dB peak

Monitor with both peak and RMS meters for best results. Always leave headroom!

Phantom power is a method of providing DC voltage (typically 48V) to condenser microphones through the same XLR cable that carries audio. It's called "phantom" because it's invisible to devices that don't need it - dynamic microphones ignore it safely.

Why it's needed: Condenser mics require power for:
- Charging the capacitor plates
- Powering the internal preamplifier
- Maintaining the polarization voltage

How it works: +48V is sent equally down pins 2 and 3 of the XLR cable, with pin 1 (ground) as return. Balanced audio signals are unaffected because they're differential.

Where it comes from:
- Audio interfaces (most have a 48V phantom power button)
- Mixing consoles
- Dedicated phantom power supplies

Important notes:
- Always turn phantom power on BEFORE connecting the mic and off BEFORE disconnecting
- Won't damage dynamic mics, but can harm ribbon mics - check before enabling
- LED indicator shows when phantom power is active
- Some USB mics have built-in phantom power and don't need external 48V

No phantom power = no sound from condenser mics.

Sample Rate (measured in Hz or kHz) is how many times per second the audio is measured.

- 44.1 kHz (CD quality): 44,100 samples per second. Captures frequencies up to 22 kHz (human hearing limit). Standard for music.
- 48 kHz (professional video): Standard for film, TV, video production.
- 96 kHz or 192 kHz (high-res): Captures ultrasonic frequencies, provides more headroom for editing. Larger files, minimal audible difference.

Bit Depth determines the dynamic range (difference between quietest and loudest sounds):

- 16-bit: 96 dB dynamic range. CD quality, fine for final distribution.
- 24-bit: 144 dB dynamic range. Studio standard, more headroom for recording and editing. Reduces quantization noise.
- 32-bit float: Virtually unlimited dynamic range, impossible to clip. Ideal for field recording and safety.

For most purposes, 48 kHz / 24-bit is ideal. Higher settings create larger files with minimal benefit for typical use.