avatar

boggy

Silverado

Posts: 59 Member Since: 03/01/2012

Lead

Jan 21 12 10:50 PM

Tags : :






Dear colleagues,

Here are a couple of audio test tones, which we made some years ago, useful not primarily for classical measurements, but for gaining listening experience on acoustics phenomena, resonances or any other sort of acoustical anomalies which may exist in your room or your loudspeakers.
The usage is very simple, just play the file, and LISTEN/analyze with your brain. You will hear all sorts of unwanted additions to the original signal or its pause, which will clearly reveal any resonance in your listening space, loudspeakers, even the buzzes from the loose objects in the room, or resonances from different acoustical instruments (if you still keep it in the control room  ). 

The signal itself was generated mathematically, from the program code, quantized to 24bits, written directly into the wav file, without any recording/processing. So you can use it even to test plugins, or equipment? All ideas welcome.

Even though the archive is not that big (~20MB), after extraction, files (avi clips) will decompress into more than 1 GB, so be prepared...  
We made avi clips (xvid codec) because this was only way to inform listener which frequency is currently played.
Avi clip which cover lowest audio range, starts from 10Hz, so please be careful with listening levels... increase volume from its minimum very carefully, and control your wofer cone movement visually and/or use your finger very gently to sense it.
This lowest one I use for analyze unwanted noises from motors and suspensions of loudspeaker drivers, it is also useful for testing all (audible) room resonances below 100Hz.

Test is based on Hann wavelet with four periodes. Similar tests is extensively used in loudspeaker design, but often with measurement microphone. Sometimes it is called "cosine tone burst" or similar.

Here is the archive:
http://myroom-acoustics.com/images/stories/bozo_test/test.rar

All ideas and impressions are more than welcome. Enjoy! 

NOTE: "BOZO" in the company name isn't famous clown, but starting letters of names of owners (Bogic Petrovic and Zorica Davidovic)


Quote    Reply   
avatar

barry hufker

Diamond Forever

Posts: 12,251 Member Since:26/01/2011

#1 [url]

Jan 22 12 8:47 PM

Bogic,

That is a wonderful test.  It is long to sit through but that's the nature of a thorough test.  I'll have to run the tones a time or two more to really appreciate what I'm hearing, but I didn't hear anything dreadful so that's good.


Quote    Reply   
avatar

maarvold

Aqua Marine

Posts: 3,191 Member Since:23/01/2011

#3 [url]

Jan 24 12 12:26 AM


I am more than a little bit obsessive about my listening environment.  After just a few minutes of playing back various frequencies, I could tell that these tests are going to reveal some new, previously unknown, problem areas in my room.  And I was thrilled to find out I have quite strong level at 12 Hz and above (although 10 and 11 are essentially silent).  Thank you very much for posting--it would take many tedious hours to create something like this manually.  

Michael Aarvold Audio Engineer

Quote    Reply   
avatar

dandan

Silverado

Posts: 74 Member Since:02/02/2012

#5 [url]

Feb 10 12 1:38 PM



Thanks boggy. I think this deserves a link in the  Interesting Topics section, as well as a dedicated thread here.
 I have wanted something like this for years. For those reading who haven't had a look, these files are short Bursts of Tone, 1Hz apart for the LF etc. etc. 
Such bursts are ideal for stimulating  modal and any other ringing. 
I have done this job organically, making human noises, oh alright, grunts, tuned by watching LabMeter by rustykat.com. This technique has the advantage of movable source and servo integrated reception and analysis  :-)
One finds all sorts of things, e.g. Alcoves ringing like bells, particular areas ringing, and then not ringing when a trap is introduced. 

If I may add a use-enhancing suggestion:-

I converted the AVI to a QuickTime Movie. Dropped the Movie into GarageBand.
Now I can see thumbnail pictures on the time line showing Frequency.
So I can navigate instantly to that Frequency.  Instant Random Access.  
It gets even better, Loops.

A wonderfully useful tool, again thanks B.


DD


Quote    Reply   
avatar

boggy

Silverado

Posts: 59 Member Since:03/01/2012

#6 [url]

Feb 10 12 4:52 PM






.......If I may add a use-enhancing suggestion:-I converted the AVI to a QuickTime Movie. Dropped the Movie into GarageBand.Now I can see thumbnail pictures on the time line showing Frequency.So I can navigate instantly to that Frequency.  Instant Random Access.  It gets even better, Loops.

-dandan


 
It is possibly needed to be careful with audio compression, if it exist in your process.
I rendered basic avi with uncompressed wav file "glued" to the video, then I used xvid codec only for video part, with an option "leave audio as is"... 
Testing avi files are that big after unpacking because audio streams, not video. There is a great compression ratio in .rar file because .wav file is artificially programmed sample by sample, not recorded... so there is no noise or any other artifacts which are not easy to compress (I mean file compression). 
So it is probably better to "extract" only untouched audio, in wav format, from original avi file and use it independently with mpeg video, (which is used for thumbnails)...

 A wonderfully useful tool, again thanks B.......

-dandan

You're welcome 



Quote    Reply   
avatar

dandan

Silverado

Posts: 74 Member Since:02/02/2012

#7 [url]

Feb 12 12 1:39 PM

Quicktime doesn't have a 'leave the audio as is' option but it has every other option. 
GarageBand and the strangely named Logic seem to automatically convert anything they see. The SRC in particular has caused many problems in Mastering.
Anyway I suspect the QT Export defaults to 16Bit 44.1K Linear PCM. 
I can and will force it to whatever your original file format was boggy.
Was it 24/48K

DD

Quote    Reply   
avatar

octafish

Silverado

Posts: 139 Member Since:28/10/2011

#9 [url]

Feb 12 12 3:55 PM



By coincidence I just opened them up in QT a few minutes ago, so I can confirm that this is indeed the case: they are in 16/48.

Quote    Reply   
avatar

dandan

Silverado

Posts: 74 Member Since:02/02/2012

#10 [url]

Feb 12 12 5:14 PM


Thank you both. Seems Quicktime has hidden talents. I found that Inspector window octafish, thanks to you. Turns out that my Exported QT versions had been converted to 44.1 K. 
So I will redo them. 
Just in case eyes are glazing over with this minutae, let's refocus on the big picture. This is a great tool for stimulating modal and other ringing. Playing this as a QT movie in a DAW gives quick random access to the visible frequencies, plus looping. 

DD

Quote    Reply   
avatar

boggy

Silverado

Posts: 59 Member Since:03/01/2012

#13 [url]

Sep 5 12 8:02 AM

...................The signal itself was generated mathematically, from the program code, quantized to 24bits, written directly into the wav file, without any recording/processing. ...................

-boggy

I have an error which I missed last time I reading... 
Audio part is quantized to 16bits not to 24bits.
Sampling rate is 48kHz.

Of course, it is possible to generate audio wav part quantized to 24bits, but at  time when we worked for this test, there was some (old) video players which cannot play videos with 24bit audio streams... so we decide to give up from 24bit stream, in favor of portability.

Sorry again.

Quote    Reply   
avatar

iris

Gold Finger

Posts: 798 Member Since:17/01/2012

#15 [url]

Sep 26 16 1:38 PM

This looks like it might be quite helpful in my current situation.
Sadly I have no experience using test tones, so curious if there is a small instructional with the download, or a link?
Can anyone tell me if this would help suss out a currently untreated, gym sized room?
And do the tones need to be played out of the pre positioned designated Studio Mains to test accurately?

In my instance, it will be a high res PA system that has yet to be purchased and placed.
Could I begin room testing with my mackie HR824's placed approximately where mains will go?
Will they be loud enough for a very large room? Should I even bother like that... or do I need to wait until
the actual sound system is placed?
Anybody?
Thanks!

Quote    Reply   
Add Reply

Quick Reply

bbcode help