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Loudness Compensation Calculator

When you listen quieter than your reference level, the ear hears less bass and treble. Enter both levels to get an approximate EQ boost that restores the balance — the idea behind a hi-fi "loudness" button.

⚠ Approximate guidance, not a precise calculation. This uses a simplified model of how equal-loudness contours (Fletcher–Munson / ISO 226) change with level — it captures the right shape (big bass boost, small treble boost, flat mids as volume drops), not exact ISO 226 dB values. Treat it as a starting point for a low-volume EQ tilt and trust your ears; it doesn’t measure or process audio.

Reference / mix level (dB SPL)

Your listening level (dB SPL)

Rough levels are fine — only the difference drives the compensation. A conversation is ~60 dB; a loud mix room ~85 dB.

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Suggested boost per band (centre = no change, right = boost, left = cut):

Why Quiet Needs More Bass

Human hearing isn’t equally sensitive at every frequency, and the imbalance gets worse at low volume. The equal-loudness contours (Fletcher–Munson, updated as ISO 226) show that as overall level drops, the ear loses sensitivity to bass most of all, and to the top treble somewhat — while the midrange stays relatively constant. So a mix that sounds balanced loud will sound thin and dull played quietly.

Loudness compensation counteracts that by boosting the lows (and a touch of the highs) when you turn down — historically the "loudness" switch on amplifiers. The amount needed grows with how far below your reference you’re listening: this tool estimates that boost per octave band from the difference between your two levels.

Why "approximate"

A precise implementation evaluates the full ISO 226 equal-loudness contours at both levels. This calculator instead uses a simplified per-octave model tuned to the well-established shape of those curves. It’s great for understanding the effect and getting a sensible starting EQ tilt, but the exact dB figures won’t match a lab measurement — so set it by ear and adjust to taste.

Frequently Asked Questions

What is a "loudness" control?

A switch or curve on amplifiers and players that boosts bass (and some treble) at low volume, compensating for the ear’s reduced low-frequency sensitivity when listening quietly — exactly what this calculator estimates.

Are these exact ISO 226 numbers?

No. They come from a simplified model tuned to the shape of the equal-loudness contours, not a full ISO 226 evaluation. The shape (lots of bass, a little treble, flat mids) is right; the exact dB are approximate, so trust your ears.

What levels should I enter?

Your reference is the level you mix or normally listen at; the listening level is how loud you’re actually playing now. Approximate dB SPL is fine — only the difference between them matters for the compensation.

What if I listen louder than my reference?

Then you’d theoretically trim a little bass and treble (the opposite tilt). It’s unusual, but the calculator shows it — small negative values mean a slight cut.

Should I leave this EQ on all the time?

No — it’s tied to a specific volume difference. Use it as a starting tilt for quiet listening and remove or reduce it as you turn up. For critical mixing, work at a consistent reference level instead.

Does it process my audio?

No. It only suggests an EQ tilt from the numbers you enter. Apply the boosts in your EQ and adjust by ear.

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