# Impulse-response Measurement Excitation Generator

Package a single impulse, full-period MLS or logarithmic sweep with parameters and measurement instructions.

> Canonical page: https://elysiatools.com/en/tools/audio-impulse-response-generator

- **Category:** Media

- **Keywords:** excitation, impulse response, MLS, inverse sweep

## Overview

ZIP includes excitation.wav and parameters.json. MLS ignores duration/fade and uses exact (2^order − 1)-sample periods. Impulse has exactly one nonzero sample and no fade. Logarithmic mode requires end > start and at least 1 second; it includes a normalized reverse sweep inverse.wav encoded as float32 to preserve gain. This is an excitation package, not a recorded or measured IR. Lower amplifier and headphone volume before playback; no automatic playback. Levels are peak targets from −60 to −3 dBFS, not calibrated dB SPL. PCM24 WAV uses an exact frame count rounded from duration × sample rate. Periodic frequencies must stay below 0.45 × sample rate. Square, triangle and sawtooth waves use at most 16 harmonics below that limit with conservative peak normalization. Fades may occupy at most half the active signal. Noise and silence ignore frequency, phase and sweep controls. Excitation is a test input, not a measured room impulse response; a separate recording and deconvolution stage is required.

## Inputs

- **Sample rate** (select)
- **Active duration (seconds)** (number)
- **Fade (ms)** (number)
- **Noise seed** (number)
- **Excitation method** (select)
- **Start frequency (Hz)** (number)
- **End frequency (Hz)** (number)
- **Level (dBFS)** (number)
- **MLS order** (select)
- **Repetitions** (number)
- **Leading silence (seconds)** (number)
- **Trailing silence (seconds)** (number)

## When to use

- Preparing test signals to capture room acoustics, reverb decay times, or speaker frequency responses.
- Generating paired forward sweeps and normalized float32 inverse sweeps for offline deconvolution.
- Exporting cycle-exact MLS sequences or single-sample Dirac impulses for DSP and audio hardware characterization.

## How it works

- Select an excitation method (logarithmic sweep, MLS, or single impulse) and configure your system sample rate.
- Define frequency boundaries, active duration, target peak dBFS levels, and leading or trailing silence margins.
- Download the generated ZIP archive containing excitation.wav, parameter metadata in parameters.json, and inverse.wav for logarithmic sweeps.
- Route the excitation audio through your playback system, capture the acoustic or electrical output, and convolve the recording with the inverse signal.

## Use cases

- Measuring studio listening room reflections and reverberation decay using full-band log sweeps.
- Testing loudspeaker driver response and phase alignment with MLS excitation in anechoic or semi-reflective spaces.
- Validating audio filter phase and latency in DSP hardware using single-sample impulse packages.

## Frequently asked questions

### Does this tool provide the final measured impulse response file?

No. It generates the excitation test signals. You must play the file through your hardware, record the acoustic response with a microphone, and deconvolve the recording.

### What is included in the downloaded ZIP archive?

The archive contains excitation.wav and parameters.json. For logarithmic sweep configurations, it also includes inverse.wav encoded as 32-bit floating point.

### Why are duration and fade settings disabled or ignored in MLS mode?

MLS signals require complete mathematical cycles of exactly (2^order − 1) samples to preserve periodic autocorrelation properties without windowing artifacts.

### Are the signal levels calibrated to sound pressure level (dB SPL)?

No. Signal levels represent digital peak amplitudes from −60 to −3 dBFS. Physical acoustic SPL depends on your audio interface, amplifier, and monitor gain.

### Why is the inverse sweep encoded as float32 instead of PCM24?

32-bit floating-point format preserves the wide dynamic range and exact amplitude weighting required for accurate linear deconvolution without digital clipping.

## Related tools

- [Audio Chirp Sweep Generator](https://elysiatools.com/en/tools/audio-chirp-sweep-generator): Generate phase-integrated linear or logarithmic sine sweeps as a mono WAV.
- [Audio Read-Along Cue Generator](https://elysiatools.com/en/tools/audio-read-along-cue-generator): Generate sentence or word-level timestamp cues from a narration audio and its script, for karaoke-style reading and language learning.
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- [Audio Ambience Loop Generator](https://elysiatools.com/en/tools/audio-ambience-loop-generator): Extract the background ambience/room tone from a fragment and generate a seamless loop of any target length.
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## Samples

- [Copyright-Free FLAC Audio Samples](https://elysiatools.com/en/samples/flac-samples): Lossless FLAC audio samples for testing and development, mirrored from MP3 set with nature sounds and meditation music
- [Copyright-Free MP3 Audio Samples](https://elysiatools.com/en/samples/mp3-samples): Collection of royalty-free audio samples for testing and development purposes including nature sounds, meditation music, and ambient audio
- [Copyright-Free WAV Audio Samples](https://elysiatools.com/en/samples/wav-samples): Uncompressed PCM WAV audio samples for testing and development, mirrored from MP3 set with nature sounds and meditation music
- [Android Image Processing Java Samples](https://elysiatools.com/en/samples/android-image-processing-java): Android Java image processing examples including reading/saving images, scaling, and format conversion

## Related content

- [Audio Test Signal Generation, Review and Handoff](https://elysiatools.com/en/hubs/audio-test-signal-generation-review-and-handoff): Create sweep, stereo or measurement-excitation fixtures, check their format and expected signal behavior, and hand off parameters, review evidence and file hashes without claiming a measured acoustic response.