Removing Metronome clicks from play-along CD's

[robbys]

Dear Audacity Forum,

As a pianist/pianoteacher I use so called "play along" CD's for my pupils and myself aswell. Among these recordings there are Mozart Piano Concerto's. Here the orchestra-part is recorded and the pianist plays 'live' as soloist the pianopart along.
For keeping the tempo and the beat there are so called Metronombeats used that are on the recording as well. For a musicschool recital however, these audibly beats used are of course extremely annonying. Sometimes these metronom beats occur during measures where the piano has no orchestra accompagnement. Then these noises are easy to remove with Audacity. Sometimes however these noises also happen to be heard when the orchestra is playing as well.
My question is : how do I remove in this latter case the metronomsounds without destroying/erasing the music
that the orchestra is playing?!
The metronom noise is a kind of "wooden block that are hit together" sound alike. I used Audacity's effect: 'Click Removal' but that didn't worked out in this case, for whatever reason.
Can anybody help me to accomplish my request?

Many greetings and thanking anybody for your replie in advance.


Rob

[steve]

I doubt that you will be able to eliminate the clicks completely, but it may be possible to reduce them so that they are less annoying.

Can you upload a couple of short samples somewhere on the internet and post links to them. One sample of a couple of seconds of the metronome on its own, and a couple of seconds of the metronome and orchestra, both in WAV or FLAC format.

[Xyz_39808]

I think I know where stevethefiddle is going with this.

Just use the repeat function to loop the clicks for the duration of the song.

Use invert and align your looped click track with the song so that the peaks clicks match the troughs.

Quick Mix 'em and they should cancel out.

[steve]

There are various techniques that could be used, but it's difficult to guess which method will be best without actually having an example.

[robbys]

OK, I put 2 exemplas on the Internet for the people that want to help me with this problem. Please go to http://home.versatel.nl/gabriele.hermans/
then click on the left side of the site on the "test" button. On the next screen there are 2 buttons: Muziek: this is de .wav file were you can hear the metronom clicks WITHOUT the orchestra. Muziek2: this is de .wav file were you can hear the metronom clicks WITH the orchestra. I sincerely hope that somebody comes up with a solution! Rob

[steve]

You will need to use Audacity 1.3.6

The clicks are quite long and contain a broad range of frequencies. This means that neither filtering or noise/click removal will be effective. However, the clicks are panned dead centre, and they have been electronically generated so the clicks are pretty well identical throughout. This gives us a couple of options:

Method 1.
The simplest method is to use Audacity 1.3.6 and apply the "Voacal Removal" effect ("Utilities" section of the Effects menu). This will do a pretty good job of removing most of the click, however, the downside is that the resulting audio will be in mono and anything in the recording that is panned dead centre will also be removed. This is definitely worth trying as it is so quick and easy. If the effect causes too much damage (too much other sound is removed), then you will have to use method 2.

Method 2.
This is a bit more tricky, but it will leave the music virtually unchanged (almost no damage at all). This is the method that Xyz_39808 suggested earlier.

In this picture I have imported the clicks onto track one, and the orchestra with music onto track 2.

I have then used the "Invert" effect on track one and zoomed in very close to align track 1 and track 2 perfectly.
It is important that the clicks align perfectly - zoom in until you can see the individual samples. Note that there is one loud click followed by two quiet clicks and make sure that the loud clicks line up exactly with the quiet clicks.
Click on the vertical scale of the tracks to zoom in vertically - this will help you to align them. (Right click on the vertical scale to zoom out again).

align-clicks.png (95.3 KiB) Viewed 4767 times

Now we have to make the amplitude (volume level) of the clicks in track 1 (Metronome) match those in track 2 (Orchestra).

To do this, select one of the loud clicks in track 2 and open the "Amplify" effect. Do not apply it - we just want to see how much below 0.0dB it is.

amplify-amount.png (72.02 KiB) Viewed 4762 times

We can see in this picture that the click in the orchestral track can be amplified by 19.6dB to bring it up to 0.0dB. That means that the peak is -19.6dB. (Now cancel the Amplify effect).

Repeat this for the equivalent click on the metronome track. When I do that it tells me that the peak is at -19.3 dB.
This means that the Metronome track is 0.3dB louder than the clicks on the orchestra track (zero dB is full scale - any waves that are below full scale are measured in dB below zero, hence -19.3dB is 0.3dB louder than -19.6dB).

We will now Amplify the metronome track by -0.3dB (minus 0.3) to make the clicks the same on both tracks.

Select both tracks, and use "Mix and Render" from the "Tracks menu".

You can hear the result here: http://easyspacepro.com/audacity/exampl ... clicks.wav