If your audio is going onto your pc its probably a lot less hassel to use software to do any noise reduction/filtering. There's loads of audio dsp software about even at reasonable prices I think?. I think cool edit pro is shareware and can do this sort of thing on most common audio formats. On Thu, 9 Mar 2000 06:52:45 -0800 David Covick wrote: > Duilio, > > Depending on what frequencies you are trying to filter out and those of > interest........ > You could implement a lowpass, highpass or bandpass filter. > This could be done quite simply with an op-amp and approximately 2 resistors > and 2 capacitors for the lowpass or highpass. Double the hardware just > mentioned and combine the two for a bandpass filter. > This is all for a single voltage power supply. > If you have a dual polarity power supply you could do a bandpass filter with > just one op-amp. > > David > > > ----- Original Message ----- > From: Duilio Foschi > To: > Sent: Thursday, March 09, 2000 7:47 AM > Subject: recording w/o noise > > > > I am preparing a tutorial for my new application using Lotus' ScreenCam. > > > > I have done all the video recording and now have to add the voice track. > > > > This is easily done (at least in theory) using the mic attached to the > > sound card of my PC. > > > > The problem is: > > > > all sort of noises enter my room from down the street and in all the tests > > I made the noise is well audible in the recorded track. > > > > Still I have all my things here and would hate to migrate to a different > > place. > > > > Also I guess that if I don't rent a professional recording room - what > > would be expensive and troublesome - I will find noise - more or less - > > everywhere. > > > > Is there a hw solution (a special mic ?) to filter out the noise when > > recording and/or a sw solution (Goldwave ?) to filter out the noise from > > the WAV file after the recording ? > > > > Thank you > > > > Duilio Foschi > > ---------------------- Dan University of Exeter