Hello Jörn, Thanks for writing. Your response isn’t too late, and it may have saved me from potential grief. From what I’ve read, FFADO 2.0 will work with the MOTU Traveler (first generation) and the 896HD. These are the very two MOTU devices that I own. Some years back (prior to learning of Ambisonics), I used Linux because there was a lot of great freeware available for Linux users. I used (and still have) a boxed version of Red Hat Linux 8.0. In the interest of multi-media, I recently downloaded Ubuntu Studio 11.1 for x86 (downloaded as an iso file, and then burned to DVD). Naturally, there is debate as to the “best” Linux for media use. My interest in Linux at this time is because you (and others) had recommended or suggested AmbDec. From what I’ve read thus far, I look forward to trying AmbDec. Chances are, however, I’ll create the requisite audio files using one platform (i.e. Linux) from B-formatted files, and then play them back using a PC-based DAW. The impetus for the PC-based DAW is because I’m using hardware that I designed and built for automating psychoacoustic experiments. In a nutshell, the hardware (photo uploaded) is akin to a voltage-operated surface-controller that works in real time because it gets feedback (based on a listener’s response via a response box) before a subsequent stimulus is presented. My hardware controller works well with Nuendo 4.3 and Audition 2, so I’ll probably stick with these (PC) DAWs. If a dummy driver is needed to create audio files using the AmbDec software, then I imagine JACK or FFADO will work. I have never used JACK; is it similar to ReWire? For my background noise, I have recorded several “representative” establishments/restaurants with noise levels hovering around 60-65 dBA, 70 dBA, and 75-80 dBA. I used a TetraMic connected to a Roland R-4 Pro recorder to make the 4-channel (raw, or A-format recordings). I then used VVMic and the cal (IR) files that came with the TetraMic to obtain the B-format files. A separate audio recorder was used to provide phantom power to my Earthworks (omnidirectional) calibration mic and record SPLs. An acoustic calibrator provided the cal tone and reference level for playing back the background (restaurant) noise at actual levels. To me, recording a single venue and then arbitrarily adjusting the playback level to achieve a particular SNR is not representative of real-world scenarios. Amplifying a quiet coffee house isn’t representative of a “louder” establishment. I don’t think many would disagree with this idea, but most researchers use one source for background noise regardless of the background noise level or desired SNR. Although Ambisonics may not be the ideal way of presenting background noise, it has to be a heck of a lot more realistic than methods previously used to test speech comprehension in noise, which are then reported in peer-reviewed literature. To give you an idea of the stimuli being used to evaluate cochlear implants, I have uploaded a few sentences (stimuli) and the respective background noise used by cochlear implant researchers. The first file is a stereo stimulus file and can be downloaded from
www.elcaudio.com/examples/ci_stim_stereo.wav Without independently adjusting either the left or right gain, the SNR is 0 dB (silence between sentences was removed to obtain the signal level in dB). If you listen to this first file under headphones, it’s easy to ignore the noise and concentrate on the signal. Things are a little more blurred when listening through loudspeakers. A cochlear implant user doesn’t have the luxury of headphone listening or spatial signal segregation (assume a single implant). For your enjoyment, I also ran the stereo signal through a cochlear implant simulator that generates monaural files. (Note: “stim” in the file names refer to stimulus, whereas “sim” refers to simulation.) A monaural simulation of the above stereo file is here: www.elcaudio.com/examples/ci_sim_mono.wav and a stereo simulation file (noise in one channel and signal in opposite channel, which isn’t spatially realistic) is available here: www.elcaudio.com/examples/ci_sim_L_R.wav Imagine listening to your music (or a conversation) with this much distortion! Mostly, ask whether you believe these wav files, stereo or mono, are representative of real-world listening. This should shed some light on why I wish to improve the methods we use to test and evaluate hearing impaired listeners. Thanks, as always, for your help and insight. Kind regards, Eric -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20120111/99ae4bb7/attachment.html> -------------- next part -------------- A non-text attachment was scrubbed... Name: dtlg010.jpg Type: image/jpeg Size: 66729 bytes Desc: not available URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20120111/99ae4bb7/attachment.jpg> -------------- next part -------------- A non-text attachment was scrubbed... Name: dtlg009.jpg Type: image/jpeg Size: 43122 bytes Desc: not available URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20120111/99ae4bb7/attachment-0001.jpg> _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
