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.)
v1.9 targets minsdk 9 and xlargescreens
v1.8 minor changes
v1.7 output includes Android Build.MODEL string
v1.6 allows to send results as an email
v1.4 confirms play/record capability by send/receive of samples to the audio hardware
Questions: email email@example.com
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This astounding collection of Brazilian-Pop-Jazz compositions by renowned Brazilian keyboardist and pianist Luciano Alves features amazing percussion grooves, top-notch improvisations and sublime keyboard textures.
On this repertoire Luciano showcases his ability to speak a universal musical language and proves why he is considered one of the best Brazilian musician/composers.
He has six CDs: Quartzo, Baobá, Mosaico, Brazil Today, Luciano Alves Interpreta Ernesto Nazareth, Só o que a gente gosta (Luciano & Bettina). More than 60 of his tunes are currently in iTunes, Amazon, Rhapsody, CD Baby, etc.
In 1976, he joined the Os Mutantes (Brazilian pop-group), traveling throughout Brazil and Italy and recording the Mutantes ao Vivo LP. For 10 years he joined the Pepeu Gomes band as keyboardist and arranger, appearing with him three times at the Montreux Festival. He also recorded with Caetano Veloso, Moraes Moreira, Sergio Dias, L. Shankar and Do Um Romão, among others.
Since 1985 he has performed solo or with his band both in Brazil and abroad. In the classical music area, he has performed as a soloist with the Brazilian Symphony Orchestra in many concerts. In 1991 he toured Denmark, spotlighting Afro-Brazilian rhythms and his CDs.
In 2009 was released his CD Luciano Alves Interpreta Ernesto Nazareth and since 2010 he is performing in duo with Brazilian singer Bettina Graziani promoting the jazz/bossa-nova CD "Só o que a gente gosta".