Mailing ListMailing List   FAQFAQ   SearchSearch   MemberlistMemberlist   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Possible issue with Sonogram frequency range

 
Post new topic   Reply to topic    www.hairersoft.com Forum Index -> Discussion
View previous topic :: View next topic  
Author Message
greekgoddj



Joined: 25 Jan 2016
Posts: 2

PostPosted: Mon Jan 25, 2016 11:54 pm    Post subject: Possible issue with Sonogram frequency range Reply with quote

Hi everyone,

I am loading a 48000Hz sweep from 0-24000Hz. I view the Sonogram for the entire duration and find that the upper frequency is 12000Hz and not 24000Hz. The test tone's frequency content for the second half of the sweep (12000 -24000Hz) is folded downwards. This is what the sonogram looks like: and the test asset is here for anybody that wants to try it locally http://www.digenis.co.uk/random/0-24000.wav

Is this a genuine bug or am I missing something? Having compared it with Audition I am leaning towards the former.

Thanks[/url]
Back to top
View user's profile Send private message
Martin Hairer
Site Admin


Joined: 08 Nov 2006
Posts: 1613

PostPosted: Tue Jan 26, 2016 9:55 am    Post subject: Possible issue with Sonogram frequency range Reply with quote

Hi,

click on the small "gearbox" icon and change the maximal frequency to 24kHz, this will give you the expected result.

By default, sounds are subsampled by a factor two before the sonogram is computed (since most sounds of interest have not much interesting frequency content above 10kHz so you get better resolution in the low frequencies), this results in the "folding" you observed, see

https://en.wikipedia.org/wiki/Aliasing#Folding

for an explanation of this phenomenon. Regards,

Martin

--
HairerSoft
http://www.hairersoft.com/



_______________________________________________
Amadeus forum mailing list
Unsubscribe / change settings at http://two.pairlist.net/mailman/listinfo/forum_list
Back to top
View user's profile Send private message Send e-mail Visit poster's website
greekgoddj



Joined: 25 Jan 2016
Posts: 2

PostPosted: Tue Jan 26, 2016 9:56 pm    Post subject: Reply with quote

Ahh of course! How did I miss that!? That works just fine and makes sense. Many thanks!
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    www.hairersoft.com Forum Index -> Discussion All times are GMT
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group