HOLMImpulse: Measuring Frequency- & Impulse-Response
 User Name Stay logged in? Password
 Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read Search

 Software Tools SPICE, PCB CAD, speaker design and measurement software, calculators

 Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
 15th October 2009, 03:20 PM #481 askbojesen   diyAudio Member   Join Date: Mar 2003 Location: Denmark, Copenhagen 1/N-Octave smoothing <=> Frequency dependent window New version: Version 1.4.1.4 (2009-10-15) Bugfixes: * Factor of 2 when calculating 1/N octave filters * Show legends on butmaps can be unchecked * Invert amplitude causes normalization to be invalid New User Guide with Mathematics v0.0.6: http://holmacoustics.com/holmimpulse.php Or HOLMImpulse > Help > 'User Guide (Checks for update)' on page 15 to 22 I derive why: 1/N-Octave smoothing <=> Frequency dependent window __________________ Follow your first Impulse with HOLMImpulse
john k...
diyAudio Member

Join Date: Aug 2004
Location: US
Quote:
 Originally Posted by askbojesen New version: n page 15 to 22 I derive why: 1/N-Octave smoothing <=> Frequency dependent window
__________________
John k.... Music and Design NaO dsp Dipole Loudspeakers.

gedlee
diyAudio Member

Join Date: Dec 2004
Location: Novi, Michigan
Quote:
Worked for me. I read the section in question and remain unconvinced. In fact his own example shows how the smoothing rejects the delayed noise. The point here is that in this example thats what you want, but what if there is some delayed diffraction effects - they shouldn't be rejected by the smoothing, but they will be with this technique.

The math only shows how a filter in the frequency domain has an analog as a window in the time domain. It does not prove that the two things will yield the same results for a spectral smoothing done as suggested in this discussion. I think that its clear that they won't.
__________________
Earl Geddes Gedlee Website

 15th October 2009, 06:44 PM #484 soongsc   diyAudio Member     Join Date: Mar 2005 Location: Taiwan So if they don't yeild the same results, what advantage does one have over the other? Why would we want it one way or the other? __________________ Hear the real thing!
gedlee
diyAudio Member

Join Date: Dec 2004
Location: Novi, Michigan
Quote:
 Originally Posted by soongsc So if they don't yeild the same results, what advantage does one have over the other? Why would we want it one way or the other?
Clearly the time domain windowing is going to make a speaker look better. Its advantage is that its easy.

Take for example a mouth reflection from a waveguide. These are delayed in time and will therfor be cut-off at some point by the shortened time window at higher frequencies when smoothing is applied per the technique shown here.
__________________
Earl Geddes Gedlee Website

Last edited by gedlee; 15th October 2009 at 06:52 PM.

 15th October 2009, 07:10 PM #486 Key   diyAudio Member   Join Date: Jan 2009 Well I have found the smoothing to be closer to what I actually am hearing. Couldn't this be useful for at least getting an approximation of the way we actually hear things in a room? That is what I have been using it for personally so I don't see the smoothing as useless exactly. Maybe not totally accurate because as you point out you are probably throwing away some audible artifacts along with some of the reflections that I don't normally hear. But I guess I just don't find the reflections that a mic picks up exactly useful to what I am testing for.
gedlee
diyAudio Member

Join Date: Dec 2004
Location: Novi, Michigan
Quote:
 Originally Posted by Key Well I have found the smoothing to be closer to what I actually am hearing. Couldn't this be useful for at least getting an approximation of the way we actually hear things in a room? That is what I have been using it for personally so I don't see the smoothing as useless exactly. Maybe not totally accurate because as you point out you are probably throwing away some audible artifacts along with some of the reflections that I don't normally hear. But I guess I just don't find the reflections that a mic picks up exactly useful to what I am testing for.
My data says the exact opposite. Group delayed signals are highly audible, increasing in audibility at higher SPLs. This effect would be ignored with the time domain windowed technique, but not with a true frequency averaging (albeit this kind of thing is never highly significant in the frequency domain). "Smoothing" makes a lot of sense, but not if it rejects signal components that we know cause audible artifacts.
__________________
Earl Geddes Gedlee Website

 15th October 2009, 07:38 PM #488 Key   diyAudio Member   Join Date: Jan 2009 I just am not sure about a lot of things which people claim are audible. My system seems to be immune to all types of things most experts claim should be audible. But I am still testing so no conclusions on group delay and diffraction effects yet.
diyAudio Member

Join Date: Mar 2003
Location: Denmark, Copenhagen
How do you smooth ?

Quote:
 Originally Posted by gedlee The point here is that in this example thats what you want, but what if there is some delayed diffraction effects - they shouldn't be rejected by the smoothing, but they will be with this technique.
How do you smooth?

__________________

diyAudio Member

Join Date: Mar 2003
Location: Denmark, Copenhagen
Quote:
Still a problem?
__________________

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is Off Forum Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Site     Site Announcements     Forum Problems Amplifiers     Solid State     Pass Labs     Tubes / Valves     Chip Amps     Class D     Power Supplies     Headphone Systems Source & Line     Analogue Source     Analog Line Level     Digital Source     Digital Line Level     PC Based Loudspeakers     Multi-Way     Full Range     Subwoofers     Planars & Exotics Live Sound     PA Systems     Instruments and Amps Design & Build     Parts     Equipment & Tools     Construction Tips     Software Tools General Interest     Room Acoustics & Mods     Music     diyAudio.com Articles     Car Audio     Everything Else Member Areas     Introductions     The Lounge     Clubs & Events     In Memoriam The Moving Image Commercial Sector     Swap Meet     Group Buys     The diyAudio Store     Vendor Forums         Vendor's Bazaar         Sonic Craft         Apex Jr         Audio Sector         Acoustic Fun         Chipamp         DIY HiFi Supply         Elekit         Elektor         Mains Cables R Us         Parts Connexion         Planet 10 hifi         Quanghao Audio Design         Siliconray Online Electronics Store         Tubelab     Manufacturers         AKSA         Audio Poutine         Musicaltech         Holton Precision Audio         CSS         exaDevices         Feastrex         GedLee         Head 'n' HiFi - Walter         Heatsink USA         miniDSP         SITO Audio         Twin Audio         Twisted Pear         Wild Burro Audio

 Similar Threads Thread Thread Starter Forum Replies Last Post MCPete Multi-Way 10 10th February 2009 01:36 AM furly Planars & Exotics 1 17th March 2006 07:59 AM mr_push_pull Multi-Way 5 30th August 2004 01:26 PM

 New To Site? Need Help?

All times are GMT. The time now is 08:43 AM.