How do I remove noise

[Gravenb]

Hello,

I just start using Audacity and want to remove all the noise areas of a talk program.
How do i do that?

Is there some way that you can select an noise area in the program that you want to remove over the whole program?
See image included.

[steve]

Usually it is better to "reduce" the noise rather than remove it completely. Dead silence between words sounds rather weird.

For reducing hiss, the Noise Reduction effect is usually quite effective: http://manual.audacityteam.org/man/noise_reduction.html
For removing or reducing low frequency rumble the "Low roll-off for speech" setting in the Equalization effect works pretty well: http://manual.audacityteam.org/man/equalization.html
For removing constant frequency hum or whistling noise, a notch filter is often the best approach: http://manual.audacityteam.org/man/notch_filter.html

For indiscriminately reducing or removing all sounds that are below a specified level, a Noise Gate is the appropriate tool. Audacity does not ship with a Noise Gate, but there's a plug-in available here: http://wiki.audacityteam.org/wiki/Nyqui ... Noise_Gate See here for installation instructions: http://wiki.audacityteam.org/wiki/Downl ... ns#install

See here for more information: http://wiki.audacityteam.org/wiki/Noise_Reduction

[barry.beattie]

Regarding the Q of the notch filter just mentioned... what's the possible upper values it can have?

Is "1" an octave wide, "3" a third octave? "10" a tenth of an octave wide? Up to 1 hundredth? Thousand?

Thanks

[steve]

Is "1" an octave wide, "3" a third octave? "10" a tenth of an octave wide? Up to 1 hundredth? Thousand?

Higher Q is a narrower notch. It's calculated as fc/bw, where fc is the centre frequency and bw is the -3dB bandwidth.
In practice you would normally use Q values in single figures.

High Q filters tend to "ring" close to the filter frequency. That's not generally a problem when notching out a constant tone, but it may be evident when using very high Q factors if there is a sudden change in the sound at that frequency. For example, try applying a 1000 Hz, Q = 100 notch filter to this short audio sample (apply the filter to the full 2 seconds):

tone.wav

(172.31 KiB) Downloaded 12 times

[Gravenb]

Thank you gus, the information was very helpful.

Now I'm facing the next challenge, what is seeking for the possibility to overlay two songs into one.

Again, thanks for all the help.

[waxcylinder]

Now I'm facing the next challenge, what is seeking for the possibility to overlay two songs into one.

so are you:

a) looking for both to play at the same time? Or,

b) overlap the end of one with the beginning of te other with a cros-fade?

WC