Place one or more measurements in an existing group. Returns the UUIDs of the measurements added.

Shift a measurement's SPL level by a fixed offset in dB (changes the measurement in place).

Phase-align measurement B to measurement A at a frequency (typically the crossover) using REW's alignment tool, and report the delay REW computed for B. The standard sub-to-main time alignment: A is the reference (mains), B is the one being delayed (sub). The result stays in the alignment tool's preview state — follow with create_aligned_sum for the summed measurement, or apply the reported delay in your DSP.

Align the SPL of several measurements to a target level (or to their average) around a centre frequency — level-matching before comparison or averaging.

Interpret a measurement's frequency response: per-band levels, flatness, and detected peaks and nulls with frequency, deviation, Q, and severity. The primary tool for answering 'what is wrong with this response?'

Trace arithmetic on a pair of measurements (first = A, second = B): division for transfer functions, subtraction for difference curves, inversion for correction curves, etc. Produces a new measurement.

Run REW's automatic EQ for a measurement: sets the equaliser model and target, matches the response to the target, and returns the generated filters plus a summary of the predicted corrected response. This is REW's own optimiser — the filters match what the REW GUI would produce.

Average several measurements into a new one — the standard way to combine multiple mic positions. Vector average is REW's recommended default for spatial averaging.

Compare two measurements (e.g. before/after EQ, left/right symmetry): the A-minus-B difference curve summarised per band, plus the largest divergences. Positive values mean A is hotter.

Set any subset of the alignment tool's knobs — measurement pair, mode (Phase/Impulse), frequency, per-side gain/delay/polarity, delay limits — and return the resulting state. For manual what-if adjustments; align_measurements does the standard phase-align in one call.

Create a new measurement containing the sum of the alignment tool's A and B with the current gain/delay/polarity settings applied. Run align_measurements (or configure_alignment) first to set the pair up.

Create a new measurement group, optionally placing measurements in it immediately. Fails if a group with the same name already exists. Returns the group including its UUID.

Delete one measurement group by UUID. There is no confirmation and no undo — REW deletes immediately. The group's measurements are not deleted.

Delete one measurement from REW. There is no confirmation and no undo — REW deletes immediately.

Control REW's signal generator. Applies whichever settings are provided (signal, level, frequency), then optionally starts or stops playback. Call with only { play: true } / { play: false } to toggle playback of the current signal.

Read the alignment tool's full state: mode, frequency, the A/B measurement indices, per-side gain/delay/polarity, delay limits, plus the modes and commands this REW version accepts.

Get a measurement's distortion data (THD and harmonics) as a table. Only meaningful for measurements captured with distortion analysis (swept sine).

Read the EQ filter bank REW holds for a measurement (type, frequency, gain, Q, enabled per filter).

Get a measurement's frequency response as a log-spaced curve, decimated to a readable number of points, plus summary statistics. For interpretation (peaks/nulls/band balance) prefer analyze_response.

List the measurements currently in a group, as measurement summaries.

Get the full summary of one measurement (all metadata REW holds for it).

List the commands REW accepts for a specific measurement.

Summary of the predicted frequency response after applying the measurement's current EQ filters (REW's prediction, not a re-measurement).

Generate and read RT60 / ISO 3382 decay parameters (EDT, T20, T30, Topt) per octave or one-third-octave band. Requires the measurement to have an impulse response (swept measurements do).

Import a text frequency response file (lines of frequency, SPL/impedance, optional phase) into REW as a new measurement. For native .mdat files use load_measurement_files instead.

Create a REW measurement from in-memory frequency response data: log-spaced magnitude values (dB SPL, or ohms for impedance) starting at startFreqHz with pointsPerOctave resolution, plus optional phase.

Import an impulse response file (e.g. WAV) into REW; each imported channel becomes a measurement.

Create a REW measurement from an in-memory impulse response: raw sample values at a given sample rate.

Import an audio file through REW's RTA, producing an RTA measurement of its spectrum.

Import a recorded sweep as a measurement: set the sweep stimulus file, then import the recorded response file. Each imported channel becomes a measurement, as if REW had measured it live.

List the raw commands a REW endpoint area accepts (application, measurements, measure, generator, rta, or a specific measurement's commands). Useful to discover REW capabilities not covered by a dedicated tool.

List the equaliser hardware models REW can generate filters for.

List all measurement groups in REW, with UUID, name, and notes. Group UUIDs are the only stable way to reference a group in other tools.

List all measurements currently loaded in REW, with UUID, index, title, notes, date, and frequency range. UUIDs are the stable way to reference a measurement in other tools.

Load one or more .mdat measurement files into REW. Returns the measurements that appeared.

Read the current sound pressure level from REW's SPL meter (SPL, Leq, SEL). Starts the meter, waits for it to integrate, reads, and optionally stops it. Play a signal (see the generator tool) to measure playback level.

Change a measurement's title and/or notes.

Predict rectangular-room standing-wave modes from room dimensions, and optionally correlate them with the measured peaks/nulls of a measurement to identify which response problems are modal (EQ can tame modal peaks; modal nulls need placement or treatment).

Run a raw alignment tool command (discover names with get_alignment_state's availableCommands). Escape hatch for commands without a dedicated tool, e.g. impulse-mode alignment or 'Aligned copy'. Extra parameters merge into the command body at the top level.

Run a raw REW command on one measurement (discover names with list_api_commands / the measurement's own command list). Escape hatch for operations without a dedicated tool, e.g. 'Trim IR to windows' or 'Estimate IR delay'.

Configure and run a swept-sine SPL measurement. Requires REW's audio input/output to be configured and a REW Pro license for API-triggered measurement. Blocks until the sweep completes and returns the new measurement.

Save every loaded measurement to a single .mdat file (overwrites an existing file at that path). Use forward slashes in the path.

Replace or update individual EQ filters on a measurement. Each entry is one filter slot; fields you omit keep their current value. Use get_eq_filters first to see the slots.

Apply fractional-octave smoothing to a measurement (changes the measurement in place).

Check the REW API connection and report application state: reachability, measurement count, and any logged errors or warnings. Run this first if other tools fail.

Change a group's name and/or notes.