Practical Mixing

How loud should you monitor when mixing (and why mixing loud fools you)

By StudioRescue Editorial

Published October 23, 2026

This question gets asked constantly and almost never answered honestly. Search it and you will find a confident number, usually 85 dB, presented as the professional standard. Search the actual standards and you will find no such requirement for music mixing anywhere. REAPER’s own user guide, which runs to over 460 pages, does not contain the phrase “dB SPL”, “sound pressure level”, “listening level” or “monitoring level” even once. There is no setting in the program to find and no official figure to hit.

That does not mean the level is unimportant. It is one of the few things in a home studio that quietly changes every decision you make. It is just that the useful advice is about consistency and about your ears, not about a target number.

Why the level changes what you hear

Your ears do not have one frequency response. They have a different one at every volume, and this is measured and standardised, not folklore.

The relevant standard is ISO 226, “Normal equal-loudness-level contours”, currently in its third edition, published in March 2023. It specifies, across 20 Hz to 12,500 Hz, which sound pressure levels at each frequency are perceived as equally loud. The important structural fact is that it does not specify one contour. It specifies a separate contour for each loudness level, because the shape is not the same at every level. If your hearing had a fixed frequency response, one curve would have done.

The direction of the change is what matters in practice. Stanford’s CCRMA course material on the equal-loudness curves puts it plainly: the curves flatten out at higher loudness levels. The spread across the frequency range narrows from roughly 70 dB at the lowest level to about 37 dB at a medium level and 28 dB at the highest. In other words, the quieter you listen, the more the extremes of the spectrum fall away relative to the midrange, and the louder you listen, the more even everything seems.

So the mechanism behind the symptom is simple:

• Mix loud and the bass and top end already sound present, so you do not add enough of them. The mix comes back thin and dull when someone plays it quietly.
• Mix very quietly and the extremes sound missing, so you overcompensate. The mix comes back boomy and harsh when someone turns it up.
• Change the level halfway through a session and the second half of your decisions are answering a different question from the first half.

The number that actually matters is a ceiling

If you want one figure to hold on to, make it this one. NIOSH, the US occupational health research agency, sets a recommended exposure limit of 85 dBA averaged over an eight-hour shift, and states that noise above 85 dBA is considered hazardous. The exchange rate is steep: for every 3 dBA increase, NIOSH recommends halving the exposure time.

For long-term listening through personal devices the WHO and ITU safe-listening standard is lower still, at 80 dB for 40 hours a week for adults, and 75 dB for children.

Put those two next to each other and a mixing week looks like what it is: roughly 40 hours of deliberate listening. “Mix at 85” is not a professional benchmark you should be reaching up to. It is the line where an eight-hour day becomes a hearing risk.

Set a level once, then stop moving it

This is the part that changes mixes, and it costs nothing.

Where a monitoring trim belongs in REAPER

If your only volume control is in software, the obvious move is to pull the master fader down. Do not. REAPER’s render takes the output of the master track, which means your render passes through the master fader on its way to the file. Using it as a monitoring knob changes the file you deliver.

REAPER has a proper place for this instead. Open View, Monitoring FX from the main menu, or hold Shift while clicking the FX button on the Master track. The official user guide describes this chain as hardware output FX and states that these FX “do not show up in renders, do not affect the metronome and are not stored in the project file”, and that you can use it to run analysis FX or to compensate for the acoustic characteristics of a particular room.

A gain or volume plugin placed there gives you a monitoring-only level control that your exported file never sees. It is also the right home for a room-correction plugin or a metering plugin, for the same reason.

How to find out what level you actually have

You do not need to measure anything to benefit from consistency. If you want to know where you are, a sound level meter at the listening position is the tool.

Phone apps are good enough for this job, within limits that NIOSH has actually tested. In their review of smartphone sound measurement apps, 10 of 130 iOS apps met their selection criteria, and three A-weighted apps came within ±2 dBA of a reference meter, which NIOSH noted matches the accuracy specified for Type 2 instruments. A follow-up study using external calibrated microphones found measurements within ±1 dB. Android fared worse in that work: of 62 apps examined, only 4 partially met the criteria. NIOSH publishes its own free Sound Level Meter app for iOS.

That is enough to tell you whether you are working at a reasonable level or at a damaging one. It is not enough to call your room calibrated.

Which decisions need which level

Consistency is the rule. Deliberately checking at a second level is the useful exception, as long as you know what each level is good for.

The one exception worth building into your habits: if you are comparing against a commercial record, the two have to be at matched level or the comparison is worthless, because the louder of the two will win on tone every time. That is a method of its own, covered in how to set up and level-match a reference track in REAPER.

What a monitoring level will not fix

• It will not fix your room. Room modes put peaks and nulls in the low end at specific frequencies in specific places. Those are still there at every volume, and a consistent level only means you are consistently hearing them.
• It will not make a mix translate on its own. It removes one variable. Checking the mix somewhere real is still a separate job, which is what why your mix sounds bad in the car is about.
• It will not fix a balance that is wrong. If the vocal is 3 dB too quiet, it is too quiet at every listening level. See how loud the vocal should be in the mix for the fader side of that.
• It will not un-tire your ears. Nothing recovers a fatigued ear inside a session except stopping. If your last hour of decisions always gets undone the next morning, the level and the session length are both suspects.
• It will not give you a number to hit. There is no setting in REAPER for this and no standard that specifies one for music, so the goal genuinely is repeatability rather than a target.

If your mixes still do not translate

1. Check that you are not moving the volume. The most common version of this problem is not a wrong level, it is three different levels inside one session.
2. Check the master fader is at unity and that any monitoring trim lives in the monitoring chain, not in the signal path that gets rendered.
3. Compare against a reference at matched level before you change anything. Most of the time the mix is closer than it feels.
4. Check it somewhere real. Phone speaker, car, cheap earbuds. If it holds up in three places it is not a monitoring-level problem.
5. Suspect the room, not the volume, if the low end is the thing that never translates. That is a different fix and no listening level substitutes for it.