I didn't catch the beginning of this thread? Just thought I'd add a comment: some microphones (e.g. cardioid) are designed to shape the gain/response, by angle, which helps to suppress feedback, e.g. from the back of the mic. Depending on how you hold the mic, it is possible to block off some of the mic audio paths (like from the back) and cause feedback. This can be very mic dependent. Juhan Leemet Logicognosis, Inc. On 2012-06-26, at 11:56 AM, Bill Unruh wrote: > On Tue, 26 Jun 2012, Dominique Michel wrote: > >> Le Mon, 25 Jun 2012 14:08:07 -0400, >> Jerry Geis <geisj@xxxxxxxxxxxxxxx> a écrit : >> >>>> The best things to do would be to use something like a dbx, a >>>> feedback suppressor. The problem is than they are expensive pieces >>>> of hardware. The principle is simple: above a given (adjustable) >>>> input level, you get an output level with a gain of 1, and under >>>> this given input level, you get a gain (adjustable)< 1. That way, >>>> the feedback will never begin, so it will never get the opportunity >>>> to become louder and louder. The dbx are mostly used to suppress >>>> feedback on stages. >>>> >>>> It should be very easy to implement such dbx as a software >>>> effect, but I don't know if something like that already exist for >>>> linux. >>>> >>>> Ciao, >>>> Dominique >>> Dominique, >>> >>> I did some quick searching and didnt see anything like that. >>> Is this something you can implement? >> >> Unfortunately not. I am good with hardware, but not a programmer. >> >> If using jack, you can try 2 or 3 effects into the jack-rack. >> >> One is the crossover-compressor. The other is the RMS expander. Maybe >> you can find some setup with them that would do the trick. >> >> Another way to suppress the feedback would be to re-tune the audio. >> Generally, feedbacks are beginning at a given frequency and into a very >> small bandwitch. By changing the pitch just a little bit will suppress >> the feedback. You can do that with the jack-rack if rubberband is > > Well no. It it is really feedback, it indicates an insability of the response > and that instability will manifest itself always, triggered if nothing else by > noise. You need to decrease the amplification of that frequency band. This is > most easily done by decreasing the amplification overall, especially as which > frequency feeds back can depend on exactly where you position your head, or > your hands, or the wall, or whatever. Ie, Unless the physical environment of > the speaker and microphone is exactly fixed, the frequency at which the > feedback occurs will depend on that environment. (I have no idea what your geomentry is so feedback could even be coming via > the computer case, rather than through the air.) Anyway, decrease the overall > amplitude of either the mic input or the speaker output. > > >> installed. It come with a LADSPA plugin called Rubber Band Pitch >> Shifter in the jack-rack. >> >>> >>> Thanks, >>> >>> Jerry >>> >>> ------------------------------------------------------------------------------ >>> Live Security Virtual Conference >>> Exclusive live event will cover all the ways today's security and >>> threat landscape has changed and how IT managers can respond. >>> Discussions will include endpoint security, mobile security and the >>> latest in malware threats. >>> http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ >>> _______________________________________________ Alsa-user mailing list >>> Alsa-user@xxxxxxxxxxxxxxxxxxxxx >>> https://lists.sourceforge.net/lists/listinfo/alsa-user >> >> >> > > -- > William G. Unruh | Canadian Institute for| Tel: +1(604)822-3273 > Physics&Astronomy | Advanced Research | Fax: +1(604)822-5324 > UBC, Vancouver,BC | Program in Cosmology | unruh@xxxxxxxxxxxxxx > Canada V6T 1Z1 | and Gravity | www.theory.physics.ubc.ca/------------------------------------------------------------------------------ > Live Security Virtual Conference > Exclusive live event will cover all the ways today's security and > threat landscape has changed and how IT managers can respond. Discussions > will include endpoint security, mobile security and the latest in malware > threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/_______________________________________________ > Alsa-user mailing list > Alsa-user@xxxxxxxxxxxxxxxxxxxxx > https://lists.sourceforge.net/lists/listinfo/alsa-user ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Alsa-user mailing list Alsa-user@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-user
