Reply by dbd March 3, 20082008-03-03
On Mar 3, 3:14 am, "dbormpou" <dborm...@bio.auth.gr> wrote:

> Hello and thanks for the response > > my exact problem is that i have recordings done with a stereo mic on a dat > machine as wav files. > they were recordings of an area that included forests, sites near the sea > near an airport and many other sites. > i want to be able to separate certain sources from the recordings and not > use the eliminated sources but the rest of the recording. what i mean is > that i want to eliminate human made sounds( cars, airplanes, ships ...) > from the rest of the recording. i hope that can assist you in giving me > some help. > > Dimitris
There are many audio editing tools that include some useful features. As an example, there is a freeware Audacity: http://audacity.sourceforge.net/ I don't suggest this as the best, but as an example. Looking at its features: http://audacity.sourceforge.net/about/features "Use the Drawing tool to alter individual sample points." suggests an editing ability to remove signal components that you can identify as separated in time or frequency from components of interest. Audacity provides the displays for doing this. "Remove static, hiss, hum, or other constant background noises." suggests more tools to remove interferences. Hum removal tools sometimes involve adaptive filters that can identify continuing components and remove them even when they overlap signals of interest. Using such tools requires that the editor understand some of the characteristics of the desired and undesired signals and uses that knowledge to make editing decisions. Examples of this would be tones that you can identify as sourced from man-made sources. Airplanes often fly with constant engine rotational rates. This produces a set of related tones and these tones can be identified and removed. There are also click or pop removal tools for removing brief high intensity events. Try Audacity or go to Google for more alternatives. There a probably better tools at greater cost. Good luck. Dale B. Dalrymple
Reply by Matthieu P. March 3, 20082008-03-03
On 3 mar, 12:14, dbormpou wrote:
> > what i mean is > that i want to eliminate human made sounds( cars, airplanes, ships ...) > from the rest of the recording. i hope that can assist you in giving me > some help. > > Dimitris
Hi. The best methods to separate several sources from only two mixtures are sparsity based BSS methods. In a first step, they estimate the mixing matrix. Then, they reconstruct the sources, in the determined (same number of sources and mixtures) or underdetermined [1,2] (more sources than observations) mixtures. Unfortunately, I am not sure that you will have a good quality of separation by only using a BSS method. Concerning the sparsity based methods, some of them, e.g. [3,4], suppose that in the analysis domain, at most one source is active. This hypothesis is very difficult to satisfy when several sources occur. On the contrary, several authors, e.g. [5], suppose that, for each source, there exist a tiny zone in the analysis domain where a source occurs alone. This assumption is less restrictive than the previous one. Note that [5] has only been proposed for the determined case, but using [2], you can easily extend [5] to underdetermined mixtures (which is the situation you met). Between both above families, you have a lot of methods that have been proposed, e.g. [6,7]. Last but not least, you have a good survey of convolutive BSS methods in [8]. Good luck! Matthieu www.ast.obs-mip.fr/puigt [1] P. Bofill, E. Monte: "Underdetermined Convoluted Source Reconstruction Using LP and SOCP, and a Neural Approximator of the Optimizer". ICA 2006: 569-576. [2] R. Saab, &#2013265942;. Yilmaz, M. J. McKeown, R. Abugharbieh, "Underdetermined anechoic blind source separation via l^{q}-basis- pursuit with q < 1". IEEE Transactions on Signal Processing, 55(8): 4004-4017, August 2007. [3] O. Yilmaz, S. Rickard: "Blind Separation of Speech Mixtures via Time-Frequency Masking". IEEE Transactions on Signal Processing, 52(7): 1830-1847, July 2004. [4] P. Bofill: "Underdetermined blind separation of delayed sound sources in the frequency domain". Neurocomputing, 16(6):627-641, 2003. [5] M. Puigt, Y. Deville: "Time-frequency ratio-based blind separation methods for attenuated and time-delayed sources". Mechanical System and Signal Processing, 19(6):1348-1379, November 2005. [6] A. Blin, S. Araki, S. Makino, "Underdetermined blind separation of convolutive mixtures of speech using time-frequency mask and mixing matrix estimation". IEICE Transactions Fundamentals, E88--A(7): 1693-1700, July 2005. [7] S. Arberet, R. Gribonval, F. Bimbot, "A Robust Method to Count and Locate Audio Sources in a Stereophonic Linear Anechoic Mixture". ICASSP 2007, vol. 3, pp. 745-748. [8] M. S. Pedersen, J. Larsen, U. Kjems, L. C. Parra, "A Survey of Convolutive Blind Source Separation Methods". Springer Handbook on Speech Processing and Speech Communication, 2007.
Reply by dbormpou March 3, 20082008-03-03
>Hi Dimitris, > >On 28 f=E9v, 23:59, "Ron N." <rhnlo...@yahoo.com> wrote: >> >> Look up blind source separation or blind signal >> separation. It's research topic, usually confined >> to particularly well defined sound sources, not >> something for which you' are likely find a canned >> application for your particular recording. > >As explained Ron, Blind Signal Separation (BSS) needs some assumptions >on sources, e.g. independence or sparsity. > >In addition, depending on your recording conditions, you could be able >to simplify the mixing model (for example, anechoic mixtures instead >of general convolutive ones). > >Try to find these informations and submit your problem to the BSS >community (http://www.tsi.enst.fr/icacentral/mailinglist.html). > >Matthieu >www.ast.obs-mip.fr/puigt >
Hello and thanks for the response my exact problem is that i have recordings done with a stereo mic on a dat machine as wav files. they were recordings of an area that included forests, sites near the sea near an airport and many other sites. i want to be able to separate certain sources from the recordings and not use the eliminated sources but the rest of the recording. what i mean is that i want to eliminate human made sounds( cars, airplanes, ships ...) from the rest of the recording. i hope that can assist you in giving me some help. Dimitris
Reply by Matthieu P. February 29, 20082008-02-29
Hi Dimitris,

On 28 f&#2013265929;v, 23:59, "Ron N." <rhnlo...@yahoo.com> wrote:
> > Look up blind source separation or blind signal > separation. It's research topic, usually confined > to particularly well defined sound sources, not > something for which you' are likely find a canned > application for your particular recording.
As explained Ron, Blind Signal Separation (BSS) needs some assumptions on sources, e.g. independence or sparsity. In addition, depending on your recording conditions, you could be able to simplify the mixing model (for example, anechoic mixtures instead of general convolutive ones). Try to find these informations and submit your problem to the BSS community (http://www.tsi.enst.fr/icacentral/mailinglist.html). Matthieu www.ast.obs-mip.fr/puigt
Reply by Ron N. February 28, 20082008-02-28
On Feb 27, 5:02 pm, "dbormpou" <dborm...@bio.auth.gr> wrote:
> Hello > > I am a biologist and i am trying to eliminate > certain sounds from a stereo recording eg the sound of > cars from the recording of a park, without loosing a > lot in audio quality. > > I have some experience in audio and computers > though i am not familiar with programming > > I need suggestions on some programms i can use > for this purpose
Look up blind source separation or blind signal separation. It's research topic, usually confined to particularly well defined sound sources, not something for which you' are likely find a canned application for your particular recording.
Reply by dbd February 28, 20082008-02-28
On Feb 28, 3:48 am, "dbormpou" <dborm...@bio.auth.gr> wrote:

> >... > Well i was kind of aware of that but i have heard samples of source > separation algorithms and i was impressed. They have pretty clearly > separated eg the guitar sounds from the rest a song, and i think > that would be the way to go for me. Any help? > > D.
Source separation algorithms require knowledge of some kind of difference between sources such as frequency, duration, direction, coherence or distribution. You have given no description of the signals or their differences for us to work with. So, you have gotten answers about collecting better recordings. Algorithm help will require more information from you. Your example may have separated coherent tones (guitar) from modulated noise (voice). What do you need to do? Dale B. Dalrymple htp://dbdimages.com
Reply by Rune Allnor February 28, 20082008-02-28
On 28 Feb, 02:02, "dbormpou" <dborm...@bio.auth.gr> wrote:
> Hello > > I am a biologist and i am trying to eliminate > certain sounds from a stereo recording eg the sound of > cars from the recording of a park, without loosing a > lot in audio quality.
The simplest problems to handle are those that never occur. The best, by far, method is to try and plan the recordings such that you use highly directional mics and position yourself such that you can point them at the source of interest with as little noise from the background as possible. Assuming you want to record sounds of birds, this means that you get as close as possible under the tree where a bird sits, and point the mic at it with the sky as background. Or you point the mic at the ducks swimming in the pond making sure that the garden shed and shrubbery act as acoustic screens with respect to the street traffic behind. Of course, that's of little help with respect to the recordings that already have been made... Rune
Reply by Jerry Avins February 28, 20082008-02-28
dbormpou wrote:
> Hello > > I am a biologist and i am trying to eliminate > certain sounds from a stereo recording eg the sound of > cars from the recording of a park, without loosing a > lot in audio quality. > > I have some experience in audio and computers > though i am not familiar with programming > > I need suggestions on some programms i can use > for this purpose
This isn't hopeless. It's not only difficult, it's best described as magic. There are no programs that pop out the result, but an experienced manipulator with a variety of techniques at his disposal might be able to effect a remarkable isolation. (Don't be taken in by the crime-lab shows. They're fiction, after all.) One hears about the few successes, not about the majority; the useless attempts. Can you isolate the sounds you want before recording them? A highly directional microphone is one way; a radio microphone close to the source is another. Jerry -- Engineering is the art of making what you want from things you can get. &#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;
Reply by manolis tsakiris February 28, 20082008-02-28
>On Feb 27, 8:02=A0pm, "dbormpou" <dborm...@bio.auth.gr> wrote: >> Hello >> >> I am a biologist and i am trying to eliminate >> certain sounds from a stereo recording eg the sound of >> cars from the recording of a park, without loosing a >> lot in audio quality. >> >> I have some experience in audio and computers >> though i am not familiar with programming >> >> I need suggestions on some programms i can use >> for this purpose >> >> Thanks >> Dimitris =A0 =A0 > >If you can use a directional microphone, so you only get the bird's >sounds. > >Clay > >*******************************************
Hello Dimitris, what exactly is your goal? what kind is the sound that you want to isolate? Is it indeed birds? Is it the sound of a specific species, or generaly you want to study the overall sound of the park? Manolis
Reply by February 28, 20082008-02-28
On Feb 27, 8:02&#2013266080;pm, "dbormpou" <dborm...@bio.auth.gr> wrote:
> Hello > > I am a biologist and i am trying to eliminate > certain sounds from a stereo recording eg the sound of > cars from the recording of a park, without loosing a > lot in audio quality. > > I have some experience in audio and computers > though i am not familiar with programming > > I need suggestions on some programms i can use > for this purpose > > Thanks > Dimitris &#2013266080; &#2013266080;
If you can use a directional microphone, so you only get the bird's sounds. Clay