EQ Surgeon: train your ear to find the exact frequency

From hearing that something's wrong to knowing where

Almost everyone can tell when a mix sounds wrong. What separates the person who fixes it is being able to say «there's a resonance around 300 Hz» instead of «I don't know, it sounds off». That translation from sensation to number is the only thing that turns an EQ into a decision rather than moving bands to see what happens.

EQ Surgeon trains that and nothing else. You hear real material — not test tones — with a curve applied, and you have to locate it. The sources come from a bank of kick, snare, cymbals, electric bass, sub, acoustic guitar, electric guitar, keys, synth, violin, cello, flute, sax, vocals and full mixes: fifteen different timbres, because 250 Hz too much on an acoustic guitar and on a kick sound nothing alike even though they share a number.

The game isn't the point: knowing instantly whether you were right is, and that's exactly what's missing when you practise by EQing your own mixes. Nobody corrects you there, and a mistake repeated two hundred times becomes your judgement.

How to play, step by step

1.Pick one of the three modes. They aren't difficulty settings on one exercise: they're chained skills, and the order matters.
2.Pick a level, from Apprentice to Surgeon. What changes is how obvious the curve is: Apprentice has 11 dB boosts, Surgeon has moves that barely clear the threshold of audibility.
3.The processed fragment plays. Replay it as often as you like: there's no clock, and listening twice before deciding is what an engineer does.
4.In Step 1 you name the band the change is in, from 60 Hz, 250 Hz, 1 kHz, 4 kHz y 12 kHz. In Step 2 you pick which of three curves was applied. In Step 3 you draw it yourself on the graph.
5.On answering you see the real curve laid over yours and the round score out of 1,000. A match is 5 rounds, so one miss decides nothing and neither does one lucky hit.

The three modes, in order

Step 1 · A vs B trains noticing that something changed, comparing original and processed (XP ×1.0). Step 2 · Multiple choice trains identifying which of three curves it is, which already demands a mental image of each filter (×1.5). Step 3 · Draw the curve trains producing it, which is what you'll actually do in front of an EQ (×2.0).

Skipping the first to jump to the last is the usual mistake, and the reason many people quit convinced they have no ear. The XP multiplier is higher in Step 3 because it's harder, not because it's where you should start.

The filters that show up aren't only bells: there are notches, high-pass, low-pass and low and high shelves. Telling a high shelf from a wide bell at 8 kHz is one of the slowest things to arrive, and it's exactly what separates tweaking from correcting.

What each level includes

ApprenticeFree: Big, obvious moves: boosts and cuts around 10 dB with wide Q. It's for calibrating what «a lot» is before trying to hear «a little».
AssistantFree: The same class of filter with less gain. Here the instrument it's applied to starts to matter: the same cut is audible on a vocal and hides inside a pad.
EngineerFree: Narrower Q and curves that no longer shout. This is where real resonances appear — the kind that in an actual mix force you to sweep to find them.
ProducerPro: Subtle moves on dense material, including full mixes where nothing is soloed and the change competes with everything else.
SurgeonPro: The limit: changes near the threshold of audibility, the kind that decide whether a master is right or nearly right. It isn't a starting point and doesn't pretend to be.

Five things that move the score

Listen to the original before the processed one, always in the same order. Switching it round by round adds a variable you aren't training.
Turn it down. Timbre differences read better at low level; loud, your ear's equal-loudness curve masks exactly what you're trying to judge.
Before answering, describe the change in words: «more body», «it bites», «it sounds hollow». Vocabulary comes before the number, in a real mix too.
If you're torn between two adjacent bands, notice which part of the instrument changed: body lives low, attack lives high. That usually breaks the tie.
Play short and often. Five rounds a day beats one hour-long session on Sunday, because what's being trained is perception, not stamina.

Frequently asked questions

Do I need an account or any install to play?

No. EQ Surgeon runs in the browser and the first three levels — Apprentice, Assistant and Engineer — play without signing up. Only Producer and Surgeon require Pro.

Are normal headphones enough, or do I need monitors?

Decent headphones are enough, and for this particular exercise they're arguably better: what's being judged is timbre change, not the room's bass. What doesn't work is a laptop speaker, which simply doesn't reproduce the low bands or the air.

Where do I start if I've never EQ'd anything?

With Step 1 at Apprentice level, and before that with Frequency Drop, which teaches which instrument lives in which zone. Without that map, naming the band is guessing.

How long before I notice a difference?

With short daily sessions, most people start telling adjacent bands apart in two or three weeks. What doesn't work is the marathon session: perception saturates in about fifteen minutes and after that you're guessing with more noise.

Where to go next

The reasoning — which filter does what, and why Q matters more than decibels — is in the EQ guide. The map of what lives in each band is in the frequency ranges guide, and the case that comes up most — two instruments fighting over the same zone — in kick and bass. To associate each band with the instrument that occupies it, Frequency Drop.