I can illustrate the real challenge here with an example.

http://jcgl.orpheusweb.co.uk/temp/ZoomCircled.png

This shows the start of side 2 of an LP of Brahms 1st Piano Concerto
(Barbirolli, Barenboim on EMI 1967) Its a lovely LP but has various various
'ticks' that are clearly audible in the quiet passages.

The tick shown here at about 6.42 sec from the start is audible with the
piano. Note the low modulation levels. The music is below about -25dB as
recorded (0dBFS was about +17dBRIAA) and the tick is smaller in amplitude
than the music.

This one is relatively easy to find by ear-eye *but* you have to zoom the
time and amplitude scales to be able to see it. If you don't the ripple at
the bottom of the previous cycle looks like the cause because it sticks out
of the displayed waveform, but it isn't.

Other ticks are harder to find. But even this one seems a challenge to find
by an 'automated' locator.

Doing an automatic locator for loud bangs is easy. But then so is seeing
them with Audacity! Question is if this kind of example can be detected by
something of the kind I've mentioned. Ideally a program that generates a
list of 'click candidates' that would find this but not be swamped with
false positives. I suspect its almost impossible, but wonder what people
think.

Took me hours to do side 1! 8-] Its only something I'd do for 'special
cases' where I really want to clean up as much as possible particularly
enjoyable examples. ... and this is a 2 LP set. 8-]

Jim

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