tag:blogger.com,1999:blog-7172143857693272648.post4007803451533855433..comments2024-03-27T17:02:00.437-07:00Comments on Audio Musings by Sean Olive: The Subjective and Objective Evaluation of Room Correction ProductsDr. Sean Olivehttp://www.blogger.com/profile/17909033506833141612noreply@blogger.comBlogger53125tag:blogger.com,1999:blog-7172143857693272648.post-44777348649406060592012-02-02T14:26:02.348-08:002012-02-02T14:26:02.348-08:00Hi Sean,
Thanks and the discussions continue. As...Hi Sean,<br /><br />Thanks and the discussions continue. As an ex recording/mixing engineer, it was popular to have at least one set of monitors equalized to the B&K curve in most of the control rooms I frequented. Urei 813B time aligns were very popular, I am dating myself now ;-).<br /><br />The other interesting side effect using the B&K target (or same target as your findings) is that the soundstage was also the best. Meaning it was not too far back or not to far forward, but just right. I am wondering in your listening tests if you found the same correlation?<br /><br />Regards, MitchMitchhttp://www.computeraudiophile.com/blogs/mitchconoreply@blogger.comtag:blogger.com,1999:blog-7172143857693272648.post-85606977327836439912012-01-31T21:24:15.600-08:002012-01-31T21:24:15.600-08:00Hi Mitch
Thanks for the useful links. Very interes...Hi Mitch<br />Thanks for the useful links. Very interesting discussions and I'm happy to hear there in consensus among us (you and B&K) in the choice of in-room target curves for equalization. I was not familiar with the B&K work until recently when someone brought it to my attention. <br /><br />The Bob Katz tonal balance chart was also interesting, and I generally agree with most of this terms and the ranges -- although the exact frequency ranges depend on the instrument,etcDr. Sean Olivehttps://www.blogger.com/profile/17909033506833141612noreply@blogger.comtag:blogger.com,1999:blog-7172143857693272648.post-14236542488547218772012-01-31T15:21:21.150-08:002012-01-31T15:21:21.150-08:00Hi Sean,
Great presentation. Have you had a chan...Hi Sean,<br /><br />Great presentation. Have you had a chance to eval some of the latest DRC software offerings? Some good discussions going on:<br /><br />http://yabb.jriver.com/interact/index.php?topic=69312.0<br /><br />http://yabb.jriver.com/interact/index.php?topic=68828.0<br /><br />http://www.computeraudiophile.com/blogs/What-tone-quality-your-audiophile-system<br /><br />Would be interested in your thoughts.<br /><br />Cheers, MitchMitchhttp://www.computeraudiophile.com/blogs/mitchconoreply@blogger.comtag:blogger.com,1999:blog-7172143857693272648.post-56533324289079228352012-01-25T16:47:09.409-08:002012-01-25T16:47:09.409-08:00Hi Joey,
You are correct. Subwoofers are generall...Hi Joey,<br />You are correct. Subwoofers are generally omni-directional over their operating frequency range although LF ports can be highly directional. So a single frequency response curve can characterize their amplitude response, which should extend down 25 Hz or lower. That being said, the room will generally dominate what you hear below 200 Hz and therefore some control or equalization is necessary. This can smooth out and extend the frequency response of the subwoofer at a single seat as long as the subwoofer has the output capability to handle the EQ boost.<br /><br />And output capability is where most subwoofers differ in performance. The factors include the performance of the transducer(s), box volume, the size of the amplifier, and the type of electronic limiting used. Ideally, you need one or more subwoofers capable of reproducing bass down to 20 Hz or more at SPL's approaching 100-110 dB @ 1 meter with minimal audible distortion.<br /><br />There have been some attempts at characterizing the useful output capability of subwoofers such as the peak SPL in 1/3-octave bands using test signals like Don Keele's co-sine shaped tone bursts (a.k.a. boinks). These signals are very short in time and therefore don't heat up the voice coil. The main issue with all of these tests is that the results don't necessarily correlate with subjective listening results using music signals. More research is needed to characterize the performance of subwoofers that correlate measurements to subjective performance.Dr. Sean Olivehttps://www.blogger.com/profile/17909033506833141612noreply@blogger.comtag:blogger.com,1999:blog-7172143857693272648.post-3572828755961553522012-01-17T11:46:05.376-08:002012-01-17T11:46:05.376-08:00Hi Dr. Olive
Thank you for sharing your work in th...Hi Dr. Olive<br />Thank you for sharing your work in this blog.<br />I have read some of Dr.Toole and your work, and it really helps a lot.<br />I know it's important for a speaker to have flat and smooth frequecy response for on-axis, early reflection, and sound power. However, how do I choose a good subwoofer? Since the frequecy range a subwoofer produces has low directiviy, does it mean that I only have to check the on-axix frequecy response? I check the spec of jbl pro subwoofer lsr4312sp for example, its low-end response does not extend as low as some other competitor's products that have similar size and price, ex. svs or velodyne. Do I miss some spec that is also important for a subwoofer?<br />Thank you.Joey Chennoreply@blogger.comtag:blogger.com,1999:blog-7172143857693272648.post-91057462550172889042010-09-08T07:35:10.046-07:002010-09-08T07:35:10.046-07:00Dear Mr Olive,
thanks for sharing your findings wi...Dear Mr Olive,<br />thanks for sharing your findings with us. How does the slope of the corrected frequency response depend on the directivity of the speaker?<br />As I understand,a conventional speaker is focusing more and more whith rising frequency. Therefore the total energy it radiates into the room reduces with frequency. Since in 4 m distance the sound is dominated by the reverberant sound field, the frequency resonses measured at the listening position will have a downward slope with respect to frequency. <br />What would be, if you test and correct a speaker with really onidirectional behaviour even at the highest frequencies. Would the slope be less inclined or flat?<br /><br />MarkusMarkusnoreply@blogger.comtag:blogger.com,1999:blog-7172143857693272648.post-40719866313516612312010-08-24T15:27:47.101-07:002010-08-24T15:27:47.101-07:00After almost three months since the last comment, ...After almost three months since the last comment, I´d like to (try and) bump this discussion.<br /><br />First of all, huge thanks for a great blog and especially this posting (and for the work you, Floyd Toole and all your colleagues have been and are doing).<br /><br />More specifically, I have two questions:<br /><br />Could you provide an evaluation of the account of "spectral envelope" as a guideline for room correction that Dennis brought up? From what I understand this might give useful insights into the psychoacoustic backgrounds of the correlation of room curve measurements and preference ratings.<br /><br />Second, as a recently converted DIY audio guy, I am working on a full range dipole design with the aims of constant directivity and smooth on- and off-axis frequency response. My question thus is this: Do I understand your research correctly if I suppose that room correction should only be needed below the Schröder frequency if dealing with well-behaved loudspeakers considering their on- and off-axis frequency response? From what I gathered, response artifacts caused by specific reflections shouldn´t be subject to EQ because their effect will vary with listener position. Am I right about this?<br /><br />I hope you will excuse the naiveté of my questions - I´m still learning...<br /><br />Thanks again for the insights you provide!<br /><br />WolfgangUnknownhttps://www.blogger.com/profile/10913540709750781718noreply@blogger.comtag:blogger.com,1999:blog-7172143857693272648.post-79608987364078359032010-06-03T06:14:09.703-07:002010-06-03T06:14:09.703-07:00Having spent 10 years as the Sales and Marketing D...Having spent 10 years as the Sales and Marketing Director of the "original" digital room correction company (SigTech), I found this incredibly interesting.<br /><br />But I have one question: given that at least two of the products you tested (Audyssey and Tact/Lyngdorf) have the ability to have variable target curves, how did you determine which curve to select AND remain completely neutral given that Harmon was testing a Harmon prototype as part of the group. And by neutral, I am not suggesting that the preferred target response was not valid, but rather the acceptability of a particular product.<br /><br />(I am submitting this as 'anonymous" since when I tried some of the other choices, nothing worked (operator error!!)Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-7172143857693272648.post-52073277061770512092010-04-28T11:10:31.411-07:002010-04-28T11:10:31.411-07:00Hi,
IMHO the discussion about flat or sloped targ...Hi,<br /><br />IMHO the discussion about flat or sloped target curves does not hit the right point. I wonder that people do not recognize how e.g. different smoothing algorithms lead to different slopes.<br /><br />At the end it is more important to study the resulting correction curve. A speaker with a good direct pulse response typically does not need too much correction, thus the correction curve should be quite flat.<br /><br />Now if a smoothing algorithm leads to a certain slope the correction will only be flat if the target follows the same slope.<br />Because correction = target minus smoothed measurement<br />(deconvolution in time domain = division in frequency domain = subtraction in logarithmic frequency domain)<br /><br />So watch out for the correction curve !Ulihttp://www.acourate.comnoreply@blogger.comtag:blogger.com,1999:blog-7172143857693272648.post-66449153416905420062010-04-21T14:13:55.925-07:002010-04-21T14:13:55.925-07:00Hi Martijn,
The measurements do indicate that the...Hi Martijn,<br /><br />The measurements do indicate that the speaker is well-behaved in the horizontal axis. These measurements I presume have been time gated to only include the direct sound, so the bump above 1 kHz in the steady-state measurements must the caused by a reflection as you suggest. If you did enough spatial averages my moving the microphone to different seats the effects of the reflection off the furniture should disappear. You can also put some absorption on the reflecting surface to confirm/deny that it's the culprit.<br /><br />What you want to avoid is attempting to "equalize" the effects of a discrete reflection.Dr. Sean Olivehttps://www.blogger.com/profile/17909033506833141612noreply@blogger.comtag:blogger.com,1999:blog-7172143857693272648.post-16770070107915354682010-04-21T09:12:01.280-07:002010-04-21T09:12:01.280-07:00Hi Sean,
Thank you for your reply. I don't wa...Hi Sean,<br /><br />Thank you for your reply. I don't want to draw away too much from the topic, but just for reference, here is a plot of the response of de speaker. These are the curves from onaxis to 90 degrees in 15 degree steps. The green curve is the average of the response at these six angles. <br />http://img709.imageshack.us/img709/2514/filex.jpg<br />In my opinion this is an excellent measurement result, except perhaps for the range above 7 khz. The response at the rear looks a bit less good, but still the irregularities at the rear don’t seem to coincide with the midrange bump measured at the listening seat (spatial average of several measurements). The vertical response looks reasonably good too. Also, my living room does not sound more live than my friend's listening room.<br />Therefore I don’t think the speaker to be the cause. The speakers are placed at about 1.4 meters away from the front wall and a little over a meter from the side-walls. However, I think the problems I measure in my room might be caused by early reflections against the furniture in close proximity of the speakers. I will have to investigate it further. <br /><br />Martijn<br /><br />MartijnMartijn Mhttps://www.blogger.com/profile/02176787713255692439noreply@blogger.comtag:blogger.com,1999:blog-7172143857693272648.post-30425390039437093502010-04-20T18:12:31.417-07:002010-04-20T18:12:31.417-07:00Hi Martijn,
Regarding your 2nd question about suc...Hi Martijn,<br /><br />Regarding your 2nd question about success in equalizing midrange peaks in your loudspeaker: I think your experiment at home confirms what we've found now in two room correction experiments using two different loudspeakers. If you have a loudspeaker with reasonably constant or smooth directivity you can equalize problems in the loudspeaker up to a fairly high frequency.<br /><br /><br />Some dipoles (e.g electrostatic panels) do have relatively constant DI above a certain frequency-like Loudspeaker M in this link: http://seanolive.blogspot.com/2008/12/part-3-relationship-between-loudspeaker.html<br /><br />Although this speaker has a horrible frequency response, it is similarly horrible at different measurement positions. It has the potential of sounding much better with equalization since removing a peak on-axis will also fix the same peak off-axis. <br /><br />In your example you noted that the visibility of the mid peak changed depending on which room it was measured. One possibility is that the peak is not due to the room per se, but in the off-axis response of the loudspeaker. The peak would be more noticeable in the measurements taken in the more reflective of the two listening rooms. I don't know if this was the case or not.Dr. Sean Olivehttps://www.blogger.com/profile/17909033506833141612noreply@blogger.comtag:blogger.com,1999:blog-7172143857693272648.post-61370653212592176132010-04-20T17:41:14.444-07:002010-04-20T17:41:14.444-07:00Hi Martijn,
Sorry for the delay in response. I do...Hi Martijn,<br /><br />Sorry for the delay in response. I don't always respond to comments in chronological order and I apparently missed yours.<br /><br />Regarding your above question about the room correction to a loudspeaker like the Revel Salon that is known to have a smooth frequency response and directivity, yet the in-room measurements indicate a peak in the midrange from the room?<br /><br />In cases like this, you have to ask yourself what caused the peak? Normally peaks associated with room resonances will not be visible above 300-400 Hz and at those frequencies the peak will vary from seat to seat. <br /><br />Constructive/destruction interferences between the direct and reflected sounds can cause a peak in the midrange but normally this disappears and changes with microphone location. If you do 3-6 spatial-averages, the peak should disappear, and the need to equalize goes away.<br /><br />If the peak survives spatial averaging then I suspect the problem is with the loudspeaker. If the loudspeaker has constant or smooth directivity you can equalize out the peak and improve the on and off-axis sound produced by the loudspeaker.<br /><br />If you don't know the on/off-axis behavior of the loudspeaker, you risk improving the reflected sounds at the expense of the direct sound.<br /><br />Finally, if you own Revel Salons, they don't need any equalization except below 300 Hz where the room dominates what you hear :) If you own good loudspeakers, you should focus on correcting the low frequency acoustical interactions between the loudspeaker and room.Dr. Sean Olivehttps://www.blogger.com/profile/17909033506833141612noreply@blogger.comtag:blogger.com,1999:blog-7172143857693272648.post-38466948745475870472010-04-20T04:17:46.101-07:002010-04-20T04:17:46.101-07:00Hi Sean,
Thanks for the response. Yes, once you ...Hi Sean,<br /><br />Thanks for the response. Yes, once you mention it I can see that there are small but significant differences between #2 and #5.<br /><br />As to papers about time windowing:<br /><br />A New Psychoacoustically More Correct Way of Measuring Loudspeaker Frequency Responses<br />Preprints 1871 (F-4) and 1963 (G-4)<br />Jorma Salmi<br /><br />A Perceptual Criterion for Loudspeaker Evaluation<br />James M. Kates<br />JAES Vol. 32, No. 12, Dec 1984<br /><br />and: Samuel Bridges<br />Effect of Direct Sound on Perceived Frequency Response of a Sound System<br />AES preprint 1644 (H-6)<br /><br />These are pretty good on the subject (maybe not to your usual standard!). There are also some interesting papers that have good experimental evidence on the subject but "come to the wrong conclusion", such as Schulein.<br /><br />Send me your e-mail on LinkedIn and I'll send you a synopsis I wrote up for another project.<br /><br />Regards,<br />DavidDavid L. Smithnoreply@blogger.comtag:blogger.com,1999:blog-7172143857693272648.post-63055760204907885902010-04-20T02:02:51.811-07:002010-04-20T02:02:51.811-07:00Dr. Olive,
Please excuse me, but is there somethi...Dr. Olive,<br /><br />Please excuse me, but is there something wrong with my two posts that you choose not te reply? I thought you might not have read them yet, but you did reply to David's post above. <br /><br />David, <br /><br />I would also very much like to see those papers. I find it very plausible that you should treat different parts of the time window differently, as reflected sounds are processed in our brain differently than the direct sound. All in all I think this kind of research would be difficult to do if you are aiming for good external validity. <br /><br /><br />Kind regards,<br /><br />MartijnMartijn Mhttps://www.blogger.com/profile/02176787713255692439noreply@blogger.comtag:blogger.com,1999:blog-7172143857693272648.post-45666382167417860112010-04-19T20:04:15.276-07:002010-04-19T20:04:15.276-07:00Hi Dave,
Thanks for your post. I agree with much ...Hi Dave,<br /><br />Thanks for your post. I agree with much of what you say.<br /><br />It is true that much of the difference between these different room correction products is related to the choice of target function. <br /><br /> Slide 24 in the presentation shows the in-room responses of the 6 room corrections tested (including no EQ). measured at the primary listening seat. Here you can see significant differences below 100 Hz and around the sound power dip in the loudspeaker. There are also significant differences in the overall slope of the curves measured over several octaves.<br /><br />You asked why Room corrections 2 and 5 scored so differently based on preference. If you carefully compare the two in-room measured curves there are significant differences in low frequency extension below 40 Hz; but more importantly, the slopes of the two curves over several octaves are sufficiently large that the difference in perceived spectral balances between two loudspeakers is quite different. This is evident in the perceived spectral balance ratings and listener comments given to RC 2 and RC5.<br /><br />The Lyngdorf product we tested most definitely applied a full band room correction (at least up to 4 kHz) since it fixed the sound power hole in the loudspeaker around 2 kHz. Room Correction 6 didn't fix the sound power problem, and in fact made it worse.<br /><br />You suggest that a variable time window applied to the HF and LF portions of the curve give the best indicators to the perceived balance, yet I am not aware of published studies that definitely support that claim. I only know of only 1 or 2 previous studies on room correction that have published results based on controlled listening tests. If you could provide me those references, I would appreciate it. <br /><br />Cheers<br />SeanDr. Sean Olivehttps://www.blogger.com/profile/17909033506833141612noreply@blogger.comtag:blogger.com,1999:blog-7172143857693272648.post-9980771452593090202010-04-18T05:49:42.743-07:002010-04-18T05:49:42.743-07:00Hi Sean,
Very interesting paper or DSP room EQ.
...Hi Sean,<br /><br />Very interesting paper or DSP room EQ.<br /><br />I have considerable experience with the Snell RCS1000 (predecessor to the Tact and Lyngdorf) and some experience with the Audysey.<br /><br />Aside from the curve of system 6, the difference between the other curves seems to be the choice of target curve. That is #1,2,3 and 5 were nearly equally good at smoothing out the curves. In fact in slide 24 there is very little difference between the result for system 2 and system 5. Would your care to speculate on why such a difference in listener preference for those two?<br /><br />Judging from the correlation between your room averaged curves and the EQ results these look like steady state EQ approaches. As you know, the problem with that is that you have to guess at what the best in-room target curve should be. A you point out EQing to a flat response would make the (more important) direct field too bright. The trouble is that the ideal room curve to achieve a good balance with the early sound is fairly indeterminate. This was a frustration with the Snell unit and I’ve observed the same with the Audysey guys. There was always an element of listening to trial EQs and then fudging the target curve to get the final balance you wanted.<br /><br />JBL seems to have chosen a 1dB per octave downslope as a target, but what if the speaker they were EQing had a different d.i.curve (or the room a different absorption curve)?<br /><br />Any reason why they didn't attempt to do room correction based on a time windowed measurement? Lots of research shows that variable time window (long at LF and short at HF) gives a measurement closer to the perceived balance. <br /><br />Clearly if we want automatic EQ to work consistently then an appropriate measurement needs to be the starting point. <br /><br />(By the way, Lyngdorf doesn’t believe in EQ for the top end of the speaker, so I’m guessing they are number 6.)<br /><br />D. Smith<br />TorontoDavid L. Smithnoreply@blogger.comtag:blogger.com,1999:blog-7172143857693272648.post-2815447698918026602010-04-07T03:35:03.586-07:002010-04-07T03:35:03.586-07:00Hi Dr. Olive,
Since my last message here I have d...Hi Dr. Olive,<br /><br />Since my last message here I have done some experiments myself. My loudspeaker system is a digitally crossed and equalized dipole with a small baffle size. This ensures a very smooth and constant DI-curve up to high frequencies. The frequency response is very flat and smooth too. However, in my (living-) room the steady-state spatial average response at the listening position is not as smooth as I would expect. In the midrange there is a peak in the response (centred a little above 1 khz). The placement and acoustics in my room are sub-optimal, but don't seem particularly bad. EQ'ing the peak completely flat gives the best subjective sound quality. <br /><br />I've set up my system in a friends' dedicated listening room. The placement and acoustics were a lot better. In his room the response at the listening place is a smoother, without the peak. There was no need for midrange EQ.<br /><br />My preliminary conclusion is that, contrary to common believe, room-EQ in the midrange can be beneficial. <br /><br />I'd still very much like to hear your opinion.<br /><br />MartijnMartijn Mhttps://www.blogger.com/profile/02176787713255692439noreply@blogger.comtag:blogger.com,1999:blog-7172143857693272648.post-79413318993284601432010-02-26T04:29:59.459-08:002010-02-26T04:29:59.459-08:00Hi Dr. Olive,
This is another great entry! Thanks...Hi Dr. Olive,<br /><br />This is another great entry! Thanks very much!<br /><br />I have one question though. It is clear to me that the B&W has issues with its directivity and that it can benefit from slight EQ to boost the dip in its power-response. However, what should you do if you have loudspeakers with very well behaved frequency response and directivity - like the Revel Studio - but there is a peak in the steady-state measurements in the midrange? It can't be the speaker, so it must be the room that causes it. Should you reduce the peak by means of EQ and if yes, to what extent?<br /><br />If you can find the time, an answer would be much appreciated!<br /><br />MartijnMartijn Mhttps://www.blogger.com/profile/02176787713255692439noreply@blogger.comtag:blogger.com,1999:blog-7172143857693272648.post-66269143304419285382010-01-03T22:20:13.672-08:002010-01-03T22:20:13.672-08:00I greatly enjoyed reading and learing from this ar...I greatly enjoyed reading and learing from this article.<br /><br />What would you say to my 'self help tip' that I took from this article, that it would be a good starting point for me to equalise my home system to -1dB per octave from 20Hz to 20kHz? (using my digital 1/3 octave equaliser, pink noise, averaged response, with microphone correction).<br /><br />Grant Stnargshttps://www.blogger.com/profile/04937893575268508575noreply@blogger.comtag:blogger.com,1999:blog-7172143857693272648.post-12597674182205437172009-12-28T12:15:43.931-08:002009-12-28T12:15:43.931-08:00Sean
do you now if the JBL Performance BassQ proc...Sean<br /><br />do you now if the JBL Performance BassQ processor uses the sound field management algorithm or is it only available threw synthesis sdec/bss systemsValentin Rhttp://www.arquitecturaaural.comnoreply@blogger.comtag:blogger.com,1999:blog-7172143857693272648.post-42614892729195287092009-11-23T00:03:21.418-08:002009-11-23T00:03:21.418-08:00Dear Mr. Olive,
I completely agree with you that ...Dear Mr. Olive,<br /><br />I completely agree with you that a flat room reponse (I mean flat by fractional octave, usualy 1/3, smoothing) sound thin and bright. This is an established fact since the old era of 1/3 of octave analog graphic qualizers. I'm only questioning that the main cause of this is the fact that most of the times the direct sound becomes bright when the stationary field response get equalized to flat. It may have a part, but I think it is just part of the story.<br /><br />First of all, some clarification. I'm an hobbyist, who started working on room equalization something like 10 years ago, just for fun. I found this issue of the spectral envelope almost by accident, exactly because I was getting the same problems you already found (much quicker than me) in your experiments. Of course, as an hobbyist, I don't even remotely have the knowledge and experience of people like you and Mr. Toole. That's why I'm asking for your opinion. Furthermore, my English isn't that good, so forgive me if some comments might appear a bit harsh. It's just that I'm a bit in troubles finding the right words.<br /><br />Regarding the spectral envelope, again, it's something I found almost by accident. Before finding it, I was using a tilted response too, following the usuale Moeller curve. On most "normal" rooms, it worked pretty well, as expected. Then I found that in my room neither the usual Moeller curve, or other kinds of tilted curves, nor a completely flat response were going to work.<br /><br />So I started searching some reference about how a given unsmoothed magnitude response will be perceived by our ear. By pure luck I found some papers in the field of speech synthesis and analysis explaining how our ear works when evaluating timbre and balance. If you look for the "warped minimum variance distortionless response" or "discrete cepstrum" keywords you'll find a lot of papers on algorithms for spectral envelope computation. <br /><br />These algorithms are optimized for speed, noise resilience and the voice range, so they are not really suited for the HiFi field. So I developed my own algorithm, checking of course that it was providing results close to the algorithms above, at least in the applicable voice range. I also checked that, with normal rooms, it was providing something close to the usual expected tilted response, as it should. Then I applied it to my quite uncommon room, and, to my surprise, it worked unbelievably well. Since then I tested it also on many other rooms and I ensure you that I never have been able to achieve a balance as uniform and similar sounding as the one I got after introducing the spectral envelope computation.<br /><br />So it seems to work pretty well, but to my surprise I found almost no reference about the spectral envelope in the standard audio literature. Don't know why. If you read the papers in the speech synthesis and analysis field the fact that our ear works on the sectral envelope, and not the traditional smoothed response, is taken for granted. It's not even questioned. The only issues are about the best and fastest way to compute it. I even found a medical paper analyzing by MRI the parts of the brain involved in the spectral envelope "computation" and analysis. So I really don't know why there's no trace of it in, say, the JAES or other audio related journals.<br /><br />Regarding my own algorithm, it's pretty simple. Having no speed and real time performance issues it has been quite easy to develop a variation of the usual fractional octave smoothing but based on a different power averaging and so providing a sort of "envelope detection" instead of simple smoothing. If you want I will provide you some Matlab/Octave code which may be used to test and evaluate it. Just write me by e-mail (d.sbragion@infotecna.it) and I'll send it to you with some explanation on how to use it.<br /><br />Thanks again for your kind attention.<br /><br />Regards,<br /><br />Denis SbragionDenis Sbragionhttp://drc-fir.sourceforge.net/noreply@blogger.comtag:blogger.com,1999:blog-7172143857693272648.post-27866817226066024982009-11-21T15:57:22.468-08:002009-11-21T15:57:22.468-08:00Hi Jimmy Olson:
Thanks for your suggestions. We a...Hi Jimmy Olson:<br /><br />Thanks for your suggestions. We are doing some research and testing of up-mixers, and hopefully I can talk about this in a future article.<br /><br />Regarding your question on focus groups and testing consumer preference for different product industrial design: Our market research people are doing that type of research, in addition to the sound quality tests that I do. <br /><br />This research is very important, since the look and feel of the product (as well as brand and marketing) often drives then product purchase decision before the consumer even gets an opportunity to hear the product. <br /><br />This is why companies like Apple are so successful. People will pay a premium for a product if it looks expensive, beautiful and is easy to operate.Dr. Sean Olivehttps://www.blogger.com/profile/17909033506833141612noreply@blogger.comtag:blogger.com,1999:blog-7172143857693272648.post-24253197293404505652009-11-21T15:45:31.953-08:002009-11-21T15:45:31.953-08:00Hi Vuki,
The programs were chosen on the basis of...Hi Vuki,<br /><br />The programs were chosen on the basis of their ability to reveal audible differences among the room corrections: the important program characteristics include spectrally dense, wide bandwidth, low bass and are relatively constant and homogeneous over time. <br /><br />The choice of mono playback was based on a previous room correction study we did that found listeners were more discriminating of room correction benefits in mono versus stereo and surround. We used a so-called ITU-R symmetrical room and loudspeaker setup in that study, and I would agree that the benefits of room correction might be even greater for non-symmetrical rooms and setups. That doesn't mean the results from our study are invalid.Dr. Sean Olivehttps://www.blogger.com/profile/17909033506833141612noreply@blogger.comtag:blogger.com,1999:blog-7172143857693272648.post-11532144517270859572009-11-21T14:45:45.704-08:002009-11-21T14:45:45.704-08:00Hi Denis,
Based on the measurements in your link,...Hi Denis,<br /><br />Based on the measurements in your link, the in-room response is very flat. In our room correction paper, we found that flat in-room target curves sound too thin and bright. The preferred in-room target has a negative slope.<br /><br />I'm not sure what you mean by room's spectral envelope. How did you measure this?Dr. Sean Olivehttps://www.blogger.com/profile/17909033506833141612noreply@blogger.com