[Sursound] Plate Reverb rocks
Hello John, Fons, and all who read my post regarding IRs and alleged artifacts. Because my observation was both new (to me) and curious, I did a bit of exploration. If nothing else, it would be important NOT to chop up speech intended for stimuli after applying reverberation. The same could be said for speech recorded in a reverberant environment. John and Fons were (of course) correct in stating that what I hear is the tail of a sound's decay. But in some instances, it's far more pronounced than I would have imagined. If an echo's tail bleeds into a subsequent word, the echo is quite pronounced when one starts from the word's onset. It is particularly noticeable when the sound that created the echo is a broadband sound because it will then sound like the impulse itself. I suppose that's why it's so pronounced. But it really appears loud, and not something that is heard when the wav file starts before any echos are present. There were differences in the onset sound when comparing natural and IR-produced reverberation. With naturally-occuring reverb, a strong "T" sound (a lingua-alveolar stop) will excite room modes and create an audible echo when the wav file is (meaning started slightly beyond the initial production of the T). But it does sound like a "T" sound and not like the "IR" shot that I was hearing. When using speech-weighted noise (600 ms duration, 100 ms rise/fall time) plus a reverb IR, the effect of echoes is quite pronounced when starting playback anywhere in the wav file. Because it's a broadband sound, it does sound like the IR (or a "gunshot"). It is like a ghost in the recording. I next created a pure-tone noise burst (730 Hz--random selection of frequency--100 ms rise/fall time) and applied the same IR used in other samples. Regardless where I started the playback, the result is a pure tone (with echo). There is a noticeable pop if one doesn't start at a zero crossing, but this would be expected. A short rise-time would fix this type of click/pop, but doesn't "fix" processed speech that is started midway in wav file. Just to convince myself that my software doesn't create artifacts, I used an IR of a different type: This time, a stereo HRTF wav file. It sounds quite good, and no pecular sounds or artifacts are present when file is started midway in the sample. Tout va bien. And to investigate other forms of reverb, I took a 1970s recording that used more than a moderate amount of plate reverb. For those of you who remember Neil Young's After the Goldrush performed by Prelude, that was my sample of choice. This was akin to the natural reverb in that clearly-pronounced stops/phonemes can be heard bleeding into subsequent phrases when you begin at a phrase. One likely reason I was hearing so much "gunshot" noise in my original samples is because there was other noise in the recording. The presence of echoes and tails created by the broadband noise gives the "gunshot" sound. None of the artifacts sounded very speech-like, but I assume this is not a fault of the IRs or processing; instead, I assume the underlying noise in the recording is being mathematically operated on when using IRs. Noise simply accentuates the effect. Noise, to include mic self noise, that are not present in the real-world environment will still be operated on by the IR, and echoes of any noise in the wav file become distinctly audible when the wav file is started from any arbitrary point (sans the beginning of the wav file). Lessons learned: I was wrong, but not entirely so. It is clear that recorded speech can't be chopped up and then presented as speech stimuli. The words or sentences to be auralized have to processed as a whole, and then presented to the listener. Even with fade-ins, the effect of lingering echoes is extremely pronounced when the IR comes from an highly reverberant space. It's less noticeable in moderately reverberant spaces, but not subtle. Clearly, arbitrary starting points aren't arbitrary when it comes to creating stimuli. Thanks again for help, and for setting me straight. One way to learn is to experiment and listen carefully. Others already knew what I had discovered for myself, but I think I have a good grasp of what's going on. Listen and learn. Happy Holidays, Eric From: John Abram To: Eric Carmichel ; Surround Sound discussion group Sent: Saturday, December 15, 2012 6:50 AM Subject: Re: [Sursound] Ghost in Machine Perhaps I'm misunderstanding, but this sounds completely normal to me. The artifacts are simply side effects of starting playback of recorded speech from the middle of a word. Is this situation going to present itself to a person using a hearing aid? I mean does the device itself act as a noise gate? -- with best wishes, John ----
Re: [Sursound] a quick tutorial video on how to create an impulse response
Hello, This tool set is great, thank you very much. Is there an email or mailing list where to ask technical questions related to these Tools? I'm testing it using the irreverence~ object for matching microphones and was wondering about the reverb effect that I get when using low smoothing values. Thanks! Hector On 2012-12-12, at 9:50 AM, Pierre Alexandre Tremblay wrote: > Dear all > > Thanks to Rodrigo Constanzo we have the first video tutorial of how to use > and abuse the fruit of the HIRT (the HISS Impulse Response Toolbox). This > time round, it is the basic use of capturing an impulse response with some of > the tools for MaxMSP. > > Feel free to watch it here: > > https://vimeo.com/55440630 > > The paper and all the externals are still available here: > > http://eprints.hud.ac.uk/14897/ > > Let us know what you think! > > p > > ps for those who prefer youtube, it will soon be up there too! > ___ > Sursound mailing list > Sursound@music.vt.edu > https://mail.music.vt.edu/mailman/listinfo/sursound ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Ghost in Machine
On Sat, Dec 15, 2012 at 07:12:35PM +0100, Justin Bennett wrote: > >To me it sounds as the normal reverb tail. Which you don't notice > >when the sound that caused it is included, as it sounds natural > >in that case. > > Sounds like that to me too. > > You would expect to hear the "lmpulse response" anyway with > any sound that has a peak - "Tom" for instance. Of course if the > "T" is present you don't hear it. But what I find strange is that > there is a kind of low-mid sweep sound just after the "bang" > Like a car going past outside. Most strange! Exactly the same description I gave it, very obvious on the noise example. Ciao, -- FA A world of exhaustive, reliable metadata would be an utopia. It's also a pipe-dream, founded on self-delusion, nerd hubris and hysterically inflated market opportunities. (Cory Doctorow) ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Ghost in Machine
Hi Eric On Sat, Dec 15, 2012 at 08:20:49AM -0800, Eric Carmichel wrote: No, this isn't at all like playing speech from middle of a word or music. Certainly beginning a recording from a waveform that would have abrupt onset would result in a pop or click. To me it sounds as the normal reverb tail. Which you don't notice when the sound that caused it is included, as it sounds natural in that case. Sounds like that to me too. You would expect to hear the "lmpulse response" anyway with any sound that has a peak - "Tom" for instance. Of course if the "T" is present you don't hear it. But what I find strange is that there is a kind of low-mid sweep sound just after the "bang" Like a car going past outside. Most strange! best, Justin Justin Bennett van der Duynstraat 61A 2515 NG Den Haag The Netherlands +31-703893912 jus...@justinbennett.nl http:://www.justinbennett.nl NEW RELEASES AND FREE DOWNLOADS FROM http://spore.soundscaper.com ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Ghost in Machine
Hello Fons, Thanks for writing. I have recordings made in highly reverberant spaces--and no such artifact exist in those recordings. Yes, a reverb tail can be heard, but not a loud, distinct, "gunshot" sound anywhere in the recordings. I will upload the 2 s IR for you (I can't go to ftp site from current coffee cafe at this moment). However, the same effect occurs with IRs downloaded from the Open Air Library--I tried them to see whether my recordings were to blame. My IRs were obtained using swept sine measurement and deconvolution, as per protocol outlined by Angelo Farina (by the way, did anyone ask if the Farina piezo-pinna transducer is related?). What might be the problem is the software used to apply the IRs to dry recordings. In my uploaded example, Sony Sound Forge 10d and its built-in Acoustic Mirror was used. Perhaps I should be using Altiverb, Waves IR3, YouVerb (I made this up), etc. I'm no expert on IRs--just getting started aside from apply Waves' and Trillium Lane's reverbs to music. Many thanks for help. Please listen to sample--it's more than a reverb tail--and pretty odd. Best always, Eric From: Fons Adriaensen To: Eric Carmichel ; Surround Sound discussion group Sent: Saturday, December 15, 2012 9:51 AM Subject: Re: [Sursound] Ghost in Machine On Sat, Dec 15, 2012 at 08:20:49AM -0800, Eric Carmichel wrote: > No, this isn't at all like playing speech from middle of a word > or music. Certainly beginning a recording from a waveform that > would have abrupt onset would result in a pop or click. To me it sounds as the normal reverb tail. Which you don't notice when the sound that caused it is included, as it sounds natural in that case. There may be another issue, but to determine this I'd need the 2 seconds B-format room IR you used. Ciao, -- FA A world of exhaustive, reliable metadata would be an utopia. It's also a pipe-dream, founded on self-delusion, nerd hubris and hysterically inflated market opportunities. (Cory Doctorow) -- next part -- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20121215/113a225d/attachment.html> ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Ghost in Machine
On Sat, Dec 15, 2012 at 08:20:49AM -0800, Eric Carmichel wrote: > No, this isn't at all like playing speech from middle of a word > or music. Certainly beginning a recording from a waveform that > would have abrupt onset would result in a pop or click. To me it sounds as the normal reverb tail. Which you don't notice when the sound that caused it is included, as it sounds natural in that case. There may be another issue, but to determine this I'd need the 2 seconds B-format room IR you used. Ciao, -- FA A world of exhaustive, reliable metadata would be an utopia. It's also a pipe-dream, founded on self-delusion, nerd hubris and hysterically inflated market opportunities. (Cory Doctorow) ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
[Sursound] Ghost in Machine--quick Addendum
Hi John, Again, thanks for writing. Questions and comments always make me think harder because I often realize that I didn't state my question/problem accurately. You have a good point regarding gating. This is often evident to hearing aid users if settings are too abrupt (expansion seems to work better than gating for minimizing some noise). In my case, I use recorded speech and noise stimuli in research. Hearing-loss and cochlear implant simulators are often used so that I can use normal-hearing listeners as research participants. The stimuli may sound natural to normal-hearing listeners. There's often the problem of conditioned listening/hearing (sound design for movies depends on this) versus critical listening. We "expect" things to sound a certain way. In the case of my auralized (better stated as processed) recordings, the artifacts aren't heard--at least not to the normal ear. But if somethng is peculiar about the recording (such as is the case of mp3 files--this relies on psychoacoustics, too), then we can't say it replicates "real-world" listening even if it sounds good or is very hi-fi. Actual recordings with a Soundfield mic don't present the curious artifact. Creating the physical reconstruction of a wave field at the listener's head is ideal--and why I got started on Ambisonics. My IR-processed recordings sound ok--so long as they're played from the beginning of the file. But the artifact clearly indicates there's something very unnatural about the stimuli. Although it can be ignored by normal-hearing persons, I have no idea how the hearing-impaired (to include central auditory processing, not just sensorineural loss) might perceive the wav files--even when played from the start. Anyway, everyone's input is always welcome. I hope my previous note and this post help clarify my question/concern. I'm still learning--and this means learning to formulate questions in understandable ways. I'm very appreciative of people's time and expertise. Thanks and Happy Holidays, Eric From: John Abram To: Eric Carmichel ; Surround Sound discussion group Sent: Saturday, December 15, 2012 6:50 AM Subject: Re: [Sursound] Ghost in Machine Perhaps I'm misunderstanding, but this sounds completely normal to me. The artifacts are simply side effects of starting playback of recorded speech from the middle of a word. Is this situation going to present itself to a person using a hearing aid? I mean does the device itself act as a noise gate? -- with best wishes, John -- next part -- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20121215/461b8332/attachment.html> ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Ghost in Machine
Hi John, Thanks for writing. No, this isn't at all like playing speech from middle of a word or music. Certainly beginning a recording from a waveform that would have abrupt onset would result in a pop or click. Have you listened to the file? I deleted the first 4 s, added a 50 ms fade-in, and the impulse sound is still there. But if you begin the wav file from the beginning, there is no artifact. The impulse-like sound (more gunshot sounding--actually sound of IR itself) is quite loud sounding, though there's no noticeable change in amplitude of waveform. That's why I use "loud" in lieu of intense--it's perceptual. If you take the normal (dry) speech or natural speech recorded in same room where the IR was recorded, no such artifact exists. You might get a small click or pop at middle of waveform--this, again, is normal and equivalent to playing, say, a cosine wave from beginning (big click because of abrupt rise time). Please listen to file if you cand download it. Use any generic wave editor (I use Audition because of big visual and easy to use) and move cursor to various parts of file. The impulse is there--almost everywhere--but only in the processed recording. Again, many thanks for writing. Kind regards and Happy Holidays, Eric From: John Abram To: Eric Carmichel ; Surround Sound discussion group Sent: Saturday, December 15, 2012 6:50 AM Subject: Re: [Sursound] Ghost in Machine Perhaps I'm misunderstanding, but this sounds completely normal to me. The artifacts are simply side effects of starting playback of recorded speech from the middle of a word. Is this situation going to present itself to a person using a hearing aid? I mean does the device itself act as a noise gate? -- with best wishes, John -- next part -- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20121215/cc43824a/attachment.html> ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Ghost in Machine
Perhaps I'm misunderstanding, but this sounds completely normal to me. The artifacts are simply side effects of starting playback of recorded speech from the middle of a word. Is this situation going to present itself to a person using a hearing aid? I mean does the device itself act as a noise gate? -- with best wishes, John ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
