Hi Recordist of the world. I have a question for you.
In the discussion list of Neoorn (listserv of ornithologist) now we have a
debate on the perfect bird field guide. Now, i would like to start a debate
about the perfect audio guide. What is the best way to present a audio
guide?. Only cut sound, narration, photos, booklet, only one cd, only
scientific name or common name, In my case, to include spanish common name
and scientific name?. How many second of cut sound?. We must to include the
bird repertoire?. Only song or only calls, or both?. Dawn chorus?.
Any comments and tips are welcome
Saludos from Mexico
,
-----Mensaje original-----
De: Marty Michener
Enviado el: Martes, 22 de Junio de 2004 02:48 p.m.
Para:
Asunto: [Nature Recordists] Fwd: Filter Techniques -- Revealed At Last.
>
>At 01:20 AM 6/22/2004 -0400, Scott wrote:
>
>>I am going to try this one more time. I went through all 13000+ messages
>>in the archives and could not find anything on basic filtering. I have
>>seen comments where one contributor stated that every recording he does
>>goes through an FFT filter. I know that not everyone here uses CoolEdit
>>but I am sure that the principles are the same. When one makes
>>recordings that catch background car noises, wind buffeting, operational
>>machinery, or water, what is the approach that you would use in
>>filtering the recording? Are there settings that one would consider
>>standard in editing any outdoor recording? If there is a good reference
>>somewhere on this, I would really appreciate knowing it. I don't have a
>>manual for my version of Pro 2.1 and I don't have an acoustic background.
>
>Dear Scott:
>
>I have written explanations of how I use Cool Edit's FFT filters over the
>years (see copy of message #376 below). The details were in a followup,
>Msg. # 394 et seq., e.g. #489, #497, #867 for tips. I have written and
>offered a short computer course, with examples files, exact settings and
>key-by-key instructions for free to anyone who wants to try it, just to
>get to know how to edit any natural recording to produce the best sound of
>a single source from what you happened to get. It included morphing
>filter designs. I had one taker who took the sound files, spectrum
>examples and course text and never got back to me, so I have no idea if
>interest was lost or it was all just too detailed or incomprehensible for
>him. It was two years and two computers ago, and I would have to hunt for
>it, now. It is about 20 megs in size, if I recall.
>
>I suggest you not try to assimilate this post all now, but print it out,
>and use it with actual field recordings as the need occurs.
>
>First, I must say, your question I think cannot be answered as such,
>because I do not know to what purpose your final recordings will be
>put. For example, Lang Elliott and Bernie Krause usually want to recreate
>sound-scapes for the listener. In contrast, I want to give the listener
>brief sound-bytes that quickly allow them to learn species identity for my
>bird-ID product, EnjoyBirds - Q.V.
>http://www.enjoybirds.com/index_files/page0006.htm So I deliberately cut
>out other ambient sounds and brutally chop out quiet places to present the
>most sound for the least disk space.
>
>Where the purpose is to surround the listener with realistic sounds, the
>use of any FFT filters is usually avoided. Any notch or band filtered out
>makes the overall recording sound harsh, muffled or hollow, depending on
>the band you have eliminated. But where three birds are singing
>simultaneously, and their frequency usage bands are exclusive, the FFT
>filters produce three separate files, one of each species, and it is in
>that mode I have some experience.
>
>Usually there are these steps in reducing a raw recording to a usable
>species example, IF THAT IS YOUR PURPOSE. I usually record from two
>angled shotgun mics at once, so initially I decide which was pointed at
>the singer most accurately, or which had the LEAST annoying extraneous
>sound in the channel, and convert that single channel to a mono file for
>editing. Often low level recordings are also normalized to 85% of max at
>this time. DO THIS FIRST, before editing. If you thought the b.g. noises
>were nearly acceptable initially, this step usually makes them so loud you
>just feel you need to do some editing. This is the order:
>
>1. Scan the whole recording for the clearest sound examples, with least
>overlap from other noise sounds.
>2. Using click-drag select, and the <delete> key, remove the loudest
>interruptions and trim the file to begin to produce a final cut. Save it
>as a new file name at each stage. If I have a recording of an American
>Robin, the original raw cuts would be saved in a project-specific
>directory named \Pittsburgh2001 or some such, and would be named as
>TURMIG00.wav, TURMIG10.wav, TURMIG20.wav, etc.and I would save the first
>one edited as TURMIG01.wav. Say it produced three songs, with some car
>noise and roosters in the b.g.
>3. I remove any impulse noise BEFORE band filtering, which would spread
>out and ruin any sharp clicks or pops.
>4. Set in spectral mode, I try to get a handle on the noise frequency
>structure, and on that of my desired species. This typically involves
>looking more closely at the lower bands, using Alt-UPARROW to expand the
>vertical spectral scale.
>
>In this example, the robin sound never falls below 800 Hz and the car
>overlaps a bit from as low as the mic recorded - say 30 - 50 Hz, up
>through 1200 or more Hz. So I know this will be a compromise. I also
>know that any FFT filter curves I make need gradual edges, NEVER sharp
>domain walls. The latter cause distress among listeners of all kinds. In
>fact, the final sound file should have the background sounds as nearly
>flat across the spectrum as possible for a listener to judge it as being
>acceptably natural. So my goal, given that the car and the birds overlap
>in the 600 to 1200 Hz region, is not to cut OUT the car, but to reduce it
>so it is the same loudness and other background sounds average in the
>range of the robin songs as well. Put another way, if the robin was not
>singing, all the sounds should average out at about the same loudness from
>bass to treble. If the b.g. is structured on this plan, it will minimize
>user questions such as:" What is that hiss?" or "What caused that roar?"
>
>5. I set and save the file to a new name, e.g. TURMIG11.wav, and begin the
>FFT trials.
>I have a starting filter: at the top the Log box is checked; on the middle
>right the top box says 40 db, the lower on -40 db.
>The line is in the middle stretching from 0 dB to 0 dB. This flat filter
>does nothing to the sound. It is the canvas, if you will, on which the
>best filter line will soon be drawn, by repeated trial and error. My
>starting filter looks like the picture saved to my web site:
>http://www.enjoybirds.com/HowItWorks/exFFT01.jpg
>
>
>
>I drag the lowest point down to about -30 and drop it. When you put the
>cursor on the line anywhere and press and hold the left button, you set a
>node on the curve. You can move it up or down, to cause gain or loss at
>that point in the curve, which becomes a "knee". Where you have loud b.g.
>noise throughout the recording, you drag the curve down, making as few new
>nodes as you need. Typically I drag 60 Hz down part way as low as the
>bottom, and 400 Hz part of that way, making a gradual curve that increases
>the bass loss as the freq. point goes down. But this will vary with each
>recording. The rule is make the b.g. in final recording sound flat, and
>only drag a point as low as it needs, avoiding vertical parts for the
>curve. Also: Do it all with one complex curve. doing successive filter
>makes it sound lousy very soon. To delete an extra knee, drag it off the
>edge of the window (that one took two weeks to figure out).
>
>Do not be tempted to raise any part of the line above 0 dB, as the ensuing
>sounds will very likely exceed the maximum signal level for the file
>without warning and the result will be permanently ruined. Keep clicking
>the [Preview] button {in the middle right} to hear the result. It will
>all sound almost the same until you do it a few hundred times. When you
>like it, click [Ok] and look at the spectrum that results. Almost
>there? Press Ctrl-Z to undo the filter, then [F2] to redo it, modify the
>position of a few nodes again, and try [Ok] again. Play with the file for
>as long as it takes to fulfill your design goals (see above). It might
>look like the example I posted:
>http://www.enjoybirds.com/HowItWorks/exFFT02.jpg
>
>Now you are ready to tackle noises WITHIN the main song band. These fall
>into two categories: those in "silences" between songs, and those within a
>song. The first is easy, the second impossible, usually, but read on.
>6. If you want to shorten the interval of "silence" between songs as with
>EnjoyBirds audio files -- which offends many biologists who want to
>preserve the rep-rate of the original singer -- just click and drag and
>[delete] the unwanted among-band sounds in your recording. I often do NOT
>wish to do this, so replace these "silent" portions with Copy-Paste
>sections from the same recording, somewhere among other "silent"
>places. This is simple:
>A. mark the offending sound to find its total length (see lower right of
>screen)
>B. find a quieter part elsewhere and click and drag a same-length portion,
>press Crtl-C to copy it.
>C. return to your offending sound, click and drag the same part of it, hit
>Ctrl-V and the quieter part will paste-replace the offending sound. Be
>sure an listen to the whole thing several times to be sure it blends ok.
>
>7. For offending sounds AMONG your wanted sounds we could likely write
>several PhD dissertations, which would really be more useful than most
>actual ones (including mine). The key is: Structure is everything. For
>files intended only for educational species-ID purposes, with a repetitive
>sound (like many wren calls), I have actually (horrors!#%*^&@#) copied a
>healthy part of the rep, and pasted it over the sick part - to make the
>sound come out to the proper number of reps and the proper length. But
>this is artistry not science and I am sure I will be kicked out of the AOU
>for admitting it, and that everybody within the sound of this message will
>. . . .never, never, never again buy my EnjoyBirds product as a
>result! The very idea! Heresy! Might as well use a Moog and be done wit=
h
it!
>
>Seriously, I also use morphing filters to remove sounds that slur up or
>down, fade in and out from WITHIN songs and sounds I wanted.
>Morphing filters work exactly like the FFT filter you just built, and all
>start with making one with the "lock to constant filter" checked.
>But if you want to remove a rooster crow, it rises then falls in
>frequency, so your curve has to follow that, or take too big a chunk out
>of the song you wanted to save. So after you nearly have it perfect as a
>single FFT curve, and you have run it and Ctrl-Z undone it several times,
>you unclick the dot next to "lock to constant filter" , so it reads:
>Morph. Now you have two identical filters, and you can make one higher
>pitched and one lower pitched to follow that bird (rooster)!
>
>Inexplicably, Cool Edit chooses these two filter with two boxes at the
>very top right of the window! It took months for me to discover these
>boxes, since up until now, you work from the top downward on the screen.
>"View initial filter graph" and "View final". These are two set points,
>and I discovered after much error that they only work well if the have the
>same number of nodes in them, so the morphing process matches set points
>and can interpolate properly.
>
>It is important to understand exactly what this does: It follows the
>"Transition curve" over the course of whatever part of the sound you have
>selected, and ranges between Initial and Final curves, depending on the
>position of the Transition Curve (TC). In the simple cas that the TC
>starts at the bottom left, and rises along a straight line to the top
>right, the program will begin with the Init. curve at the left of your
>select interval, gradually apply interpolated setting to it as it makes it
>look more like the Final Curve, ending at the right side with the curve
>exactly like the Final one. If Final and Initial are exactly alike,
>morphing is just like a constant filter. If the initial "U"- shaped dip
>is dragged a few Hz lower in pitch, and the Final a few higher, and the TC
>is made to begin low, rise fairly quickly, the fall beck to the bottom at
>the end, the filter will remove the main freq. component of the rooster's
>infamous wail. Now, all you need is to save the morph filter, e.g. as
>"rooster1" and duplicate it for the second harmonic, then the thirds, etc.
>
>Nobody said it would be easy.
>
>Although I predict that, like several of my previous posts, not a single
>person will read through all of this, let alone use any of it, I STILL
>send all my hopes for good recordings and my best regards, ;^0
>
>Marty Michener, MIST Software Assoc. Inc., P. O. Box 269, Hollis, NH 0304=
9
>
>"They that can give up essential liberty to obtain a little temporary
>safety deserve neither liberty nor safety." - Ben Franklin, 1775
>"Pues cuando ardi=F3 la p=E9rdida reverdecieron sus maizales"
>
>
>COPY: Nature Recordists Msg 376:
>
>Doug:
>
>I have DL your dove file and can tell you that I have lots of files
>that are much worse, from which I can often extract enough
>of a facsimile to produce ID teaching bird song examples.
>I had a White-cheeked Pintail from USVI, overlapping kids
>bleating for their mother's milk (uh, goats, that is), frogs in the
>same pond, and Black-necked Stilts piping to beat hell.
>
>Let me emphasize that these files are only for helping
>folks learn wild bird songs, they are not for any kind of
>scientific comparisons, and many are labeled
>"Warning, long silences have been shortened."
>(or, as: Objects in the mirror appear . . . )
>
>I have given up completely on COOLs "noise reduction"
>filters. Just when you are getting some interesting
>purification, you get all these distant bells ringing.
>And the more you listen to them, the worse of an artifact
>you decide they really are! I do it all now manually.
>Having said that, I do use many of the tricks already
>mentioned to produce a more normal-sounding final
>example. My real goal is for a learner to just say:
>"oh, that's what it sounds like." and not "What is wrong
>with that bird?"
>
>Usually, the first step is to remove clicks and crunches,
>deleting (between selected zero crossing points)
>in the time domain. Since I often walk as I record,
>foot crunches are unavoidable. I might later say
>something about how to hand hold shotguns while
>minimizing the creaks and groans of sixty-year old
>wrist joints <g>.
>
>To keep the same pacing of a longer song, I measure
>the times between each part, in milliseconds, and
>when these "silences" are plagued with loud noises
>(usually people, dogs or nearby common bird species)
>I will copy a piece of quiet ambience of exactly the same
>length, and paste-replace the noisy part. I know that there
>is a great danger in doing this that you will overwrite
>a subtle part of the bird's repertoire, so you've got to
>be on your auditory toes to do this. But this doesn't help
>when the "jaaayyyy!" overlaps with your Nightingale-thrush
>song itself!
>
>The second step is filtering, but I often use -40
>dB, which usually produces garish sounding results,
>as though coming through a culvert or from inside
>a conch shell.
>
>My favorite example was early near daybreak at
>the Cockscomb Jaguar Sanctuary in Belize when
>I had three species singing at once, all new to my library,
>and they were mutually completely separable in their
>frequency spectral bands. So, I finished with three
>20 second digital files from the same 20 seconds of
>DAT tape! That was less than 24 hours before the
>DAT became useless, ostensibly from humidity.
>
>I also make very specific (morphing) filters for
>many of the common species of birds, esp.
>the corvids, where I go through a recording and select
>specific non-target sounds and morph filter them
>into annihilation, like a frequency domain surgeon.
>Watching in the spectral mode, the file will grow to
>have black slices out of it where the jay or crow
>previously had made the file useless for teaching.
>I have literally hundreds of filters saved, named
>for each species they exclude, e.g. de-LEPVER
>for one that removes Leptotilla verreauxi. As we
>all know, human voices are the toughest, since
>our ears are exquisitely sensitive to murmurs of
>other humans.
>
>I then frequently use a file from which recognizable
>specific sounds have been removed, as a source
>of ambient hiss or whatever you wish to call it, and
>perform a complimentary filtering on it, so it provides
>the noise frequencies obviously missing from my brutally
>freq-filtered original. Then I use a mix paste, as has
>already been mentioned, to produce a more normal
>sounding result. I will frequently use COOL
>Ctrl-Z to undo, then F2 to re-try a filter or mix-paste,
>trying different levels until it sounds best.
>
>BTW I use a Bose Acoustimass system on my
>computer, rather than headphones, which tend to rot
>my ears in hot weather.
>
>As we all know, the expensive part is the time spent in
>Jamaica, Panama or Costa Rica, not that at the computer.
>
>I am not at all proud to perform this analog of cosmetic
>surgery, any more than a liposuction patient posts his operation
>on his web site. But if it helps me or others learn the songs
>better - it seems worth it.
>
>my very best regards,
>
>Marty Michener
>MIST Software Associates, Inc.
>75 Hannah Drive
>Hollis, NH
----------
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"Microphones are not ears,
Loudspeakers are not birds,
A listening room is not nature."
Klas Strandberg
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________________________________________________________________________
________________________________________________________________________
"Microphones are not ears,
Loudspeakers are not birds,
A listening room is not nature."
Klas Strandberg
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