Impulse Response
$1.10
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About Impulse Response
Turn your Android smartphone into a powerful tool for measuring the Impulse Response of audio systems.
This app will only be of interest to those who understand what an Impulse Response is!
The app generates an MLS signal from the speaker (or headset jack) and records it via the microphone, and then calculates the response of the system as a function of frequency and as a time series. The MLS signal is an alternative method to the usual sine wave sweeps, and in many ways superior.
The IR can be saved as a 44.1kHz 16bit Mono WAV file for use with third party tools such as Voxengo that use Impulse Response data.
The display shows the realtime spectral response together with the derived impulse signal as well as the step function. The spectrum can be shown in 1/1, 1/3 or 1/6 ISO octave bands, or in full pixel resolution. Another display shows the Phase of the impulse response as a function of frequency: the phase is unwrapped. The level (dB), frequency (HZ) can be adjusted via the Menu. An automatic time window feature homes in on the time region around the impulse - the duration of the window can be adjusted via the Menu.
The impulse and phase signal can be averaged, if desired. Spectrum response as well as the time series of the impulse response data can be saved in a file to the SD card for later retrieval, or offline processing (the files are simple text files easily imported into e.g. Excel), and shown alongside the realtime spectrum data.
To test the response of audio equipment, the MLS signal may be fed into its Line In input via a cable attached to the phone's headset jack. If a higher quality external microphone is to be used it can easily be attached using a Y breakout connector in the headset jack.
The MLS (Maximum Length Sequence) signal is much better than a simple pulse signal in that it has a greater power density and thus causes the equipment under test to operate in a more usual regime by exciting the whole frequency spectrum at once. This app uses a Fast Hadamard Transform to calculate the necessary convolution of the recorded signal with the MLS in order to extract the impulse response of the system.
Feedback and/or questions/problem reports are most welcome - please send email.
(If you require an Android-based SPL meter, Signal Generator, RT60 meter and Spectrum Analyser, please see our AudioTool app, also in Google Play.)
This app will only be of interest to those who understand what an Impulse Response is!
The app generates an MLS signal from the speaker (or headset jack) and records it via the microphone, and then calculates the response of the system as a function of frequency and as a time series. The MLS signal is an alternative method to the usual sine wave sweeps, and in many ways superior.
The IR can be saved as a 44.1kHz 16bit Mono WAV file for use with third party tools such as Voxengo that use Impulse Response data.
The display shows the realtime spectral response together with the derived impulse signal as well as the step function. The spectrum can be shown in 1/1, 1/3 or 1/6 ISO octave bands, or in full pixel resolution. Another display shows the Phase of the impulse response as a function of frequency: the phase is unwrapped. The level (dB), frequency (HZ) can be adjusted via the Menu. An automatic time window feature homes in on the time region around the impulse - the duration of the window can be adjusted via the Menu.
The impulse and phase signal can be averaged, if desired. Spectrum response as well as the time series of the impulse response data can be saved in a file to the SD card for later retrieval, or offline processing (the files are simple text files easily imported into e.g. Excel), and shown alongside the realtime spectrum data.
To test the response of audio equipment, the MLS signal may be fed into its Line In input via a cable attached to the phone's headset jack. If a higher quality external microphone is to be used it can easily be attached using a Y breakout connector in the headset jack.
The MLS (Maximum Length Sequence) signal is much better than a simple pulse signal in that it has a greater power density and thus causes the equipment under test to operate in a more usual regime by exciting the whole frequency spectrum at once. This app uses a Fast Hadamard Transform to calculate the necessary convolution of the recorded signal with the MLS in order to extract the impulse response of the system.
Feedback and/or questions/problem reports are most welcome - please send email.
(If you require an Android-based SPL meter, Signal Generator, RT60 meter and Spectrum Analyser, please see our AudioTool app, also in Google Play.)
All Application Badges
Paid
app
app
Android
2.2+
2.2+
Android app
App History & Updates
What's Changed
v1.8 Add button "Store IR" - allows to store the Impulse Response as a WAV file
Added longer MLS length option in Menu
v1.7 Add MLS length selection (in Menu)
Phase plot now included, with phase unwinding
Both Impulse and Step Response shown simultaneously
Visible time series now without Hann window
Output .ir file now includes time series data
Default scale and other cosmetic changes
v1.8 Add button "Store IR" - allows to store the Impulse Response as a WAV file
Added longer MLS length option in Menu
v1.7 Add MLS length selection (in Menu)
Phase plot now included, with phase unwinding
Both Impulse and Step Response shown simultaneously
Visible time series now without Hann window
Output .ir file now includes time series data
Default scale and other cosmetic changes
Price update Price changed from $1.49 to $1.10.
More downloads Impulse Response reached 500 - 1 000 downloads
Price update Price changed from $1.10 to $1.49.
Price update Price changed from $1.49 to $1.10.
What are users saying about Impulse Response
O
by O####:
by O####:
Should look into doing Impulse Responses for rooms, having the app do the same processing but allowing for a longer decay tail to capture a room, with selectable decay time.
Z
by Z####:
by Z####:
Can I use the saved files as a source for my IR reverb?
Q
by Q####:
by Q####:
Thanks for another great audio application.
Q
by Q####:
by Q####:
It looks like this app just generates white noise and compares the input response to the output response. I would have been happier if the app ran through a discrete set of frequencies and averaged a number of samples at each frequency.
Y
by Y####:
by Y####:
This does not generate any signal from the speaker. I missed the opportunity to refund this. Now I have wasted $2 on a fairly useless frequency analyzer
B
by B####:
by B####:
All I hear is white noise, just hisssssssssssssssssssssssssss
by R####:
Absolutely amazing app, can't believe that I can carry this around on my phone in my pocket. Very handy tool. Microphone calibration file upload would be great. The text on the graphs is tiny and almost impossible to to read. I revert to double stacking reading glasses or taking screen shots and zooming in.