Audio Repair and Restoration

Audio recorded at the wrong sample rate in REAPER

By StudioRescue Editorial

Published September 21, 2026

This one is frightening the first time it happens. You record a take, it sounds fine while you are recording it, and then on playback it is slower and lower than you sang it. Or the opposite: everything is fast, thin and cartoonish. It feels like the take is ruined.

It usually is not. A wrong sample rate does not damage anything. It is a labelling problem, and labelling problems are reversible. The harder part is working out whether a sample rate mismatch is actually what you are looking at, because three other REAPER settings produce a very similar symptom and have completely different fixes.

Why a wrong sample rate changes both speed and pitch

A digital audio file is a long list of numbers. Nothing in that list says how fast the numbers are supposed to come out. That instruction lives separately, in the file’s header. In a WAV file it is a field that Microsoft’s format documentation calls nSamplesPerSec, the sample rate in samples per second.

So if a file holds audio that was captured 48,000 times a second, but the header says 44,100, a player dutifully hands out 44,100 samples per second. The audio takes longer to get through, and every frequency in it drops by the same proportion. Speed and pitch always move together, which is the giveaway. If the timing is wrong but the pitch is right, this is not your problem.

Two rates cause nearly all of these mix-ups. 48 kHz is the rate recommended for professional origination, processing and interchange in the AES5 recommended practice, and it is what video and broadcast gear defaults to. 44.1 kHz is recognised in the same document for consumer digital applications, and it is what CD-era and a lot of music software defaults to. Put a machine of each kind in the same signal path and you have the classic mismatch.

First, rule out the three impostors

Do this before you touch any rate settings. All three of these change speed and pitch exactly like a sample rate mismatch does, and all three are one click to undo.

Confirm it is a rate mismatch, and measure the ratio

Now compare two numbers.

1. The file’s rate. Open the file in REAPER’s Media Explorer, which lists the source file’s own sample rate. Your operating system’s file properties panel will tell you the same thing, and it is worth checking both when the number matters.
2. The project’s rate. File, then Project Settings. The sample rate is on the first tab.

Here is the part that surprises people: those two numbers being different is not by itself a problem. REAPER supports items that use sample rate conversion, and its render path can process at the project rate and resample to the final rate. A file that honestly declares its own rate plays at the right pitch in a project running at a different rate. So if the numbers differ and the take still sounds correct, leave it alone.

The problem case is a file whose header is wrong: the interface was actually running at one rate while the file got written claiming another. Then REAPER trusts the header, converts from the wrong starting point, and you hear the offset.

Work out the ratio as the rate it was really recorded at, divided by the rate the header claims. That number is the playback rate you need.

If your take does not match any row, measure it instead of guessing. Find something in the recording whose true length you know, a metronome bar or a clap track, and divide the length it currently is by the length it should be. A ratio that lands close to 1.0884, 0.9188, 2.0 or 0.5 confirms a rate mismatch. A ratio that is some awkward number nowhere near those is a hint that something else is going on, such as clock drift between two devices rather than a single wrong label.

The fix in REAPER

1. Set the playback rate

Select the item, press F2, and enter the ratio from the table in the playback rate field. Make sure the preserve pitch option next to it is off. Preserve pitch is for musical time-stretching, where you want the tempo to change and the key to stay put. Here you want the opposite: you want speed and pitch to move together, because moving them together is exactly what undoes the original error.

2. Listen, then bake it in

Play it back. A correct ratio sounds immediately right, not nearly right. If it is close but still slightly off, you probably guessed the wrong pair of rates, so go back and check the file’s actual header rate rather than nudging the number by ear.

Once it is right, make it permanent so the setting cannot get lost. Select the item, right-click, and glue it, or render the track. Either way REAPER writes a new file at the corrected speed.

3. The cleaner route, if you want zero conversion

The playback-rate method converts the audio once, which for a spoken or sung take is a small, one-time change. If you would rather not convert at all, you can reinterpret the same samples under a corrected rate instead. Audacity is free and does this: File, Import, Raw Data is documented as handling files that have incorrect headers, and it lets you specify the sample rate to apply on import, anywhere from 100 Hz to 384,000 Hz. Set the encoding and channel count to match the original, set the rate to the true one, then export a fresh WAV and bring that into REAPER. REAPER itself does not edit file headers, so this is the one job worth leaving the project for.

Stop it happening to the next take

The mismatch almost always comes from two places disagreeing about the rate: your audio device and your project.

• Set the rate in one place and let the rest follow. In REAPER, Options, Preferences, Audio, Device has a Request sample rate tickbox. The user guide’s advice is to tick it and set the rate there, which is generally preferred, or leave it blank and use your interface’s own control panel. Pick one of those, not both.
• Match the project to the device. File, Project Settings, and set the project sample rate to whatever the interface is actually running at.
• On Windows, prefer ASIO if your interface has it. The REAPER user guide recommends ASIO where available, and notes that WASAPI may need exclusive mode. Shared-mode paths let the operating system sit in the middle and quietly convert, which is where a lot of these surprises come from.
• Do not change the device rate mid-session. Changing it in a control panel while REAPER has the device open is a reliable way to get files written with a header that no longer matches reality.
• Pick a rate per project and stay on it. If the work will end up against video, 48 kHz is the safer default. If it is music going nowhere near picture, either rate is fine. Consistency matters more than the choice.

What this will not fix

Correcting a sample rate puts back the speed and the pitch. It does not do anything else.

• It will not undo clipping. If you also recorded too hot, the squared-off peaks are still squared off at the correct speed. That is a separate repair.
• It will not fix gaps, dropouts or digital crackle. Those are missing or corrupted samples, not misread ones. See how to fix crackle and clicks in a recording.
• It will not rescue a take whose performance moved. Slowed-down audio can flatter a performance. At the correct speed, the timing and tuning you actually recorded come back.
• It will not fix two recorders drifting apart over a long take. A wrong label is a fixed ratio from the first sample to the last. Drift grows as the recording goes on, and needs a different approach.
• It will not repair a truncated or damaged file. If REAPER cannot open the file at all, that is a media problem rather than a rate problem.

If it still sounds wrong

1. Only some items are affected. Then it is per-file, so check each item’s source rate. A project can easily contain one bad import among good ones.
2. Everything in the project is affected. Then it is project-wide: transport play rate, project tempo against an auto-stretch timebase, or the device rate itself.
3. The offset is tiny and grows over the take. That is drift, not a wrong label. It points at two clocks running independently, which also shows up when audio drifts out of sync with video.
4. Your interface disappeared or changed. A device that reconnected at a different rate produces exactly this. Start with REAPER not detecting your microphone or interface.
5. The corrected file exports at the wrong rate. The render dialog has its own sample rate setting, independent of the project. Check it when you export audio from REAPER.