Audio Fundamentals
Sound waves, frequency, amplitude, phase, dB, mono vs stereo, and how ears hear — the science that makes every fader move make sense.
Learning objectives
- Explain frequency, amplitude, and phase in plain language
- Read a dB scale and know what +3 dB, −6 dB, and 0 dBFS mean in practice
- Describe the difference between acoustic level and electrical level
- Identify frequency ranges for kick, bass, vocals, guitars, and cymbals
Why fundamentals first
Pros don’t “guess and twist knobs.” They hear a problem, map it to a frequency or dynamics issue, then fix it with the right tool. That mapping only works if you understand what sound is.
This module is short, practical science — no physics degree required. Everything later (EQ, compression, gain, feedback) builds on these five ideas.
The five ideas that matter
- Frequency (Hz) — How high or low a tone is. Humans hear roughly 20 Hz–20 kHz. Kick lives low (~40–100 Hz). Vocals live mid (~200 Hz–5 kHz). Air/sizzle is 8–16 kHz.
- Amplitude / Level — How loud. We measure relative change in decibels (dB). +3 dB is a small but audible lift. +10 dB feels roughly “twice as loud” subjectively.
- Phase — Timing relationship between waves. Two mics on one source can cancel bass if out of phase. Listen for thin/hollow sound when combining similar sources.
- Dynamic range — Difference between softest and loudest useful signal. Speech has wide dynamics; a slamming snare is peaky. Compressors manage this.
- Signal-to-noise — Want program loud relative to hiss/hum. Proper gain structure protects this from mic to stream.
| Range | Hz | What lives here | Common moves |
|---|---|---|---|
| Sub / Low | 20–80 | Kick thump, bass fundamental, rumble | HPF on non-bass sources; careful boost |
| Low-mid | 80–250 | Body, boom, mud | Cut mud ~200–350 on guitars/vocals |
| Mid | 250–2k | Note definition, nasal, boxy | Clarity or boxiness lives here |
| Presence | 2k–6k | Speech intelligibility, attack | Gentle boost for preach clarity |
| Air / High | 6k–16k | Sizzle, cymbals, breath | Don’t overdo on stream — harshness |
dB without the headache
On the X32 you see meters in dB. Practical rules of thumb:
- Unity (0) on a fader = “pass the channel level as set by gain/trim” — not silence, not max.
- Clip / red = digital overload. Distortion. Avoid on channel AND mix bus AND matrix to stream.
- Healthy channel peaks during rehearsal: roughly −18 to −12 dBFS average with peaks below −6. Leave headroom.
- Headroom is empty space above your peaks for surprises (pastor laughs into mic, drummer hits hard).
If everything is loud and still “small,” you don’t need more fader — you need better gain structure and EQ. Loud is not the same as clear.
Lab — train your ears (15 min)
- Play a worship multitrack or reference song. Solo kick, then bass, then vocal. Say out loud which frequency range dominates each.
- On any channel EQ, boost a narrow band and sweep 100 Hz → 8 kHz while a vocal talks. Notice where it gets boomy, nasal, harsh.
- Turn one fader up +3 dB, then +6 dB. Describe the difference in a notebook. Pros quantify by ear.
- Clap while watching a meter. Notice peaks vs sustained level — that’s dynamics.
Video tutorials
Curated watch-list. If an embed is unavailable, use the YouTube link — then come back and do the lab. Watching without the lab is only half-training.
Frequency and EQ Explained — Audio Basics (Sweetwater)
Learn the audible spectrum, waveforms, and how frequency maps to EQ decisions.
Gain Staging Secrets Every Great Engineer Understands
Headroom, clipping, SNR — the foundation of clean live mixes.
Prove it
Module quiz
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