Impulse Response Measurer

Measure impulse response of audio system

Description

The Impulse Response Measurer app enables you to acquire, analyze, and export impulse response and frequency response measurements through a user interface.

Using this app, you can:

• Acquire impulse responses from one or more input channels to create filters and generate models for offline simulations.

• Determine whether audio devices (loudspeakers, for example) meet time and frequency specifications.

• Optimize audio systems, such as automotive-acoustic systems, to match goal specifications.

• Acquire accurate impulse response measurements for use in acoustic reporting.

×

Open the Impulse Response Measurer App

MATLAB^® Toolstrip: On the Apps tab, under Signal Processing and Communications, click the app icon.

MATLAB Command prompt: Enter impulseResponseMeasurer.

Examples

Verify Input/Output Configuration

For large systems with multiple audio devices and multiple input and output channels, tracking how reported devices and channels correspond to physical devices can be difficult. The Impulse Response Measurer provides a level monitor so that you can verify your audio I/O configuration.

To open the level monitor, click Level Monitor, .

Choose player and recorder channels in the Device section of the toolstrip. Choose the test signal and the test audio level in the level monitor. Verify that the level reported by the recorder reacts appropriately to level changes output by the player. Once you are satisfied that your system is configured correctly, close the level monitor and begin the impulse response capture.

Related Examples

• Measure and Manage Impulse Responses
• Impulse Response Measurement Using a NI USB-4431 Device

Parameters

Method — Select excitation signal as MLS or swept sine wave

MLS (default) | Exponential Swept Sine

Select the excitation signal algorithm used to generate an impulse response measurement:

• MLS –– The maximum length sequence (MLS) technique is based on the excitation of the acoustical space by a periodic pseudorandom signal. The impulse response is obtained by circular cross-correlation between the measured output and the test tone. For more details, see [2].

• Exponential Swept Sine –– The swept sine measurement technique uses an exponential time-growing frequency sweep as an output signal. The output signal is recorded, and deconvolution is used to recover the impulse response from the swept sine tone. For more details, see [1]. The swept sine technique enables you to modify additional Advanced Settings to control the excitation signal. The advanced settings apply per run:

  • Sweep start frequency

  • Sweep stop frequency

  • Sweep duration

  • End silence duration

  The value of the End silence duration is read-only and depends on the Sweep duration and Duration per Run (s): End silence duration = Duration per Run − Sweep duration

  The maximum total duration of both the sweep signal and the end silence is 60 seconds.

References

[1] Farina, Angelo. "Advancements in Impulse Response Measurements by Sine Sweeps." Presented at the Audio Engineering Society 122nd Convention, Vienna, Austria, 2007.

[2] Guy-Bart, Stan, Jean-Jacques Embrachts, and Dominique Archambeau. "Comparison of Different Impulse Response Measurement Techniques." Journal of Audio Engineering Society. Vol. 50, Issue 4, 2002, pp. 246–262.

[3] Armelloni, Enrico, Christian Giottoli, and Angelo Farina. "Implementation of Real-Time Partitioned Convolution on a DSP Board." Application of Signal Processing to Audio and Acoustics, 2003 IEEE Workshop, pp. 71–74. IEEE, 2003.

Version History

Introduced in R2018a

R2024a: View time-domain impulse response plots with logarithmic amplitude scale

Toggle between a logarithmic and linear amplitude scale for time-domain impulse response plots.

R2024a: Monitor levels of multiple player and recorder channels

Use the Level Monitor to visualize the audio levels of multiple channels for the player and recorder.

R2023b: Measure impulse responses using DAQ devices

The Impulse Response Measurer app supports data acquisition (DAQ) hardware supported by Data Acquisition Toolbox™. This functionality requires Data Acquisition Toolbox.

See Impulse Response Measurement Using a NI USB-4431 Device for an example of this workflow.

R2023a: Generate MATLAB code to measure impulse responses

Click the Generate Script button to generate MATLAB code that measures the impulse response according to the current settings of the app.

R2022b: Automatic latency compensation

Use a loopback cable to measure the audio device latency that delays the measured impulse response. You can optionally remove this latency from the captured measurements. Set Latency Compensation to Loopback Measurement to enable this feature.

R2022b: Exponential swept sine supports longer duration

When the Method is Exponential Swept Sine, the Duration per Run (s) must be less than 60 seconds. Previously, it had to be less than 15 seconds.