In my March 23rd trip report, I mentioned hearing barks every once in a while as I hiked around in the daylight hours. I managed to isolate one of those barks, actually a double bark, from my recordings and wanted to share it as an example of what I kept hearing. The weird thing about these barks is how indistinct they were, I could never get a fix on where they originated from. This example was captured a short time after 10:00 PM:
http://sites.google.com/site/mongahela/myrecordings2010-1/WS310073-AMNRLPAM-DoubleBark.mp3
Thursday, March 25, 2010
Tuesday, March 23, 2010
First Trip of the Year - March 2010
My first personal research trip of 2010 turned out to be very successful, from an audio recording perspective. I've posted three pieces of the recordings I made the evening of March 20th.
The first is a couple of loud owl hoots that came in response to some vocals and wood knocks I had made. I respond to the hoots with one vocal bark and three rock clacks. I wood knock is audible at the 20 second mark:
http://sites.google.com/site/mongahela/myrecordings2010-1/WS310073-1OwlHoots-CMNRLPAM-Detail.mp3
Some time later, in the second recording, a series of whoops has started up on the hill above me. I can't hear the early whoops in this recording at the time, and only heard the loudest whoops at the very end of the recording as I sat by my campfire. The vocal at 1:19 is punctuated with a wood knock:
http://sites.google.com/site/mongahela/myrecordings2010-1/WS310073-2AudibleWhoops-CMNRLPAM-Detail.mp3
In the third recording the vocals have turned from whoops into downward "woos" and are farther away from camp. Again, only the loudest of these were audible at the time. Vocals at 0:23 and 0:25 seconds seem to be from two different speakers. A wood knock is audible at 0:26:
http://sites.google.com/site/mongahela/myrecordings2010-1/WS310073-3DistantWhoos-CMNRLPAM-Detail.mp3
Trip Report...
On March 20th I wanted to see if the snow had melted enough that I could gain access to the research area where I recorded wood knocks for the first time, last August. I was about ten miles short of my destination when the road became impassible with deep snow left from the February "double whammy" storms that hit this part of the east coast.
So I turned to my plan B, a visit to the location where I heard (but did not record) a single wood knock as I stepped from my vehicle last September. This area is about 15 miles away from the first, but 1000 feet lower in elevation and less likely to be snowed in. But I was wrong about that.
When I arrived at my destination, I found the last half mile to be about 8 inches deep in snow. No one had driven on the snow since it fell 7 weeks ago, and only one set of boot tracks were laid down, going in, but not coming out. I parked my truck and decided to hoof it in to where I wanted to camp, check out the area, see if I could drive all the way in, etc.
I turned on my recorder before my vehicle came to a stop. I parked next to a truck with Georgia tags, apparently belonging to the boot prints that went hiking down the road ahead of me. I got my gear together and started following those tracks south, into my destination.
Along the way I was trying to listen to my surroundings. I heard a loud wood pecker from time to time. Then I thought I heard a loud bark. I stopped and listened, but nothing. I continued on and some time later, heard a loud bark again. This wasn't my imagination. It was loud enough to overcome the noise of my own hiking filling my ears. But I couldn't tell what direction it came from, it was just too indistinct. I did a lot more hiking that day, about 5 miles all together, and heard similar barks from time to time, but could never nail down their source. I should have some of them captured on audio, and will have to spend some time later to isolate them.
As I reached my turn around point, the bitter end of the driveable road where some partiers had built a fire ring, I noticed the loan hiker's boots continued on along a marked hiking trail that followed a stream down the valley. Later in the day I would follow those tracks. That guy covered some ground.
I ate my lunch by the fire ring and listened quietly. There was nothing loud enough for my ears to pick up, no more barks, but a cursory review of my audio recordings seem to have captured some possible vocals and wood knocks. Again these will bear further scrutiny (I used two recorders that weekend and have 26 hours of audio to plow through).
After lunch I picked up my gear and hiked back out to my truck. I decided the parking location of my truck was a great place to deploy my new parabolic mic for its first field trial. I went north from my truck and dropped down over the roadside and into the woods about 50 feet. I propped the parabolic up on a tripod against a fallen tree and pointed it out over a deep valley and at the ridge a half mile to the north east. This was pointing away from the area I would camp in, and would hopefully capture sounds that I wouldn't hear from camp. My camp position was in the next valley to the south and behind the ridge where I had parked.
Back at the truck I put it in 4 wheel low and carefully made my way up the snowy lane. I had tested the depths and thought with a little luck I should be able to make it through the worst. Halfway through my driving ordeal I look up the road to see the loan hiker returning. He stopped to say hi, I admitted that I was the second set of tracks he saw. Before I could ask if he'd heard or seen anything he seemed in a hurry to move on, so I ended the conversation and plowed ahead.
I got to my camp location at about 2 p.m. and had plenty of time to hike and scope out the local area. I went downstream following the hiker's boot tracks in the snow. After a half mile his tracks kept going, but I didn't. I heard another bark while I hiked back to camp and decided to head down another trail that went into the next valley to the south. I squirrel hunted this valley last fall and saw bear sign there. I was familiar with what I was seeing but wanted to scope it out as a potential recording location. Unfortunately, due to all the snow melt, a roaring stream was running down this valley and completely drowning out any other sounds (an issue the valley I camped in did not have).
I got back to my camp at about 5:00 p.m. and decided to drive out for a dinner at one of my favorite local restaurants. I returned to my camp as the sun was going down and then got down to business. I double checked the parabolic mic on the way in. It was doing fine and recording for all it was worth.
At my camp I parked about 40 feet away from the fire ring in a nice level spot and next to a small boggy area. I was in the center of a narrow valley, about 100 yards wide, and equidistant between the bases of the two ridges that framed the valley between them. The ridges and valley ran east to west, with downstream being to the east. I was at the head water, or western end of the valley. The ridges to the north and south of camp were about 100 feet higher in elevation than my campsite in the valley floor. The nearest houses were 2 miles as the crow flies to the north, three ridges and three valley's away.
As the sun set I put together a campfire and pulled out my camp chair. The audio recorder was hanging in a small tree, near my truck and away from me. But even at that distance, the sensitive mics easily picked up every little sound I made.
The night was mostly clear and a crescent moon would be setting in about four hours. While it lasted I had periodic moonlight illuminating the splotches of snow under the trees around my camp, except for the ridge to the north which was cloaked in dense red spruce evergreens. Unlike the first time I camped alone, last year, I was not feeling quite so unsettled. This was certainly a creepy camp location, but the fire kept things lit up well and I was pretty comfortable.
At about 8 p.m. it was full dark and I started to make a few wood knocks, then some bark-like vocals, then a few rock clacks, and some whistles. I tried not to over do it. I would leave long pauses of space between each of the sounds that I created. I'd been doing this for about an hour or so when I heard two loud owl hoots from the northwest, upstream and toward where the parabolic dish was located a half mile away. They were pretty loud and sounded very owl-like. I had no reason to doubt they were an owl but they did raise my suspicion a bit. So I responded to the owl hoots with a single bark vocal and then three rock clacks. You can hear this in the first recording in the thread linked at the top of this report. (You can also hear a wood knock at the 20 second point, after my bark and before my rock clacks. And no, I didn't make that wood knock).
I heard nothing more so after a bit I went to my truck, got out a beer and a little laptop computer I travel with. I sat down next to the fire and turned my back to the thick forest on the north ridge (the ridge to the south was forested in deciduous trees, but blocked form view by more conifers around my camp).
I was writing happily on an audio recording "howto" that I intend to share here on the forum. It had been about 45 minutes or so since the owl hoot, and then I heard it...
Up on the ridge behind me, maybe a couple hundred yards away, I heard a low "woo" start up and then a second, immediately followed by a hollow wood knock. The affect on me was immediate. Every bit of my senses were focused on that sound. I stopped my typing and listened keenly as two more, louder but short woos came down from the woods above. They had an eerieness to them that told me, "this is no owl", and I smiled to myself as the hair on my arms, neck and head all stood on end.
It was an involuntary smile really, but I think it was in response to the knowledge that I was experiencing for the first time an effect that has been described by so many people on this forum. I felt it was a sort of initiation.
The vocals I heard are captured in the second recording listed in the thread linked at the top of this report. After listening to the recording, it was interesting to find that the recorder captured several low woos and a couple of wood knocks which I could not hear at the time. It wasn't until the final, loudest vocalizations, that I was even aware something was up there. The recording also reveals a wood knock right in the middle of one of the vocals.
I listened intently for more vocals, but nothing else came. Somehow my mind jumped to the conclusion that these woos and the earlier owl hoots were connected, and that my vocalizations and knocks had brought this thing closer to my camp, where I was camped alone, and where no one knew of my location, in an area that had been snowed in for two months until I drove into it. With all that rushing through my mind, I just couldn't bring myself to voice a response to those vocals. I thought the risk of drawing this thing in even closer was just too great given my singular vulnerability.
Hindsight being 20/20, I probably should have made a vocal, just to let it know that I knew it was there. But that kind of reasoning didn't enter the equation. Whatever that thing was, I'm sure it knew I was down there. My campfire smoke filled the top end of the valley and the firelight would have been visible at great distance, even through those dark spruce forests.
I just stayed hunkered in my seat, not moving, just listening. Eventually, after hearing no approaching foot steps behind me, I went back to typing. I kept an ear out for more sounds, but relaxed enough to get my head back into what I was writing. It was some time later, maybe 15 minutes, when I heard the vocals again.
They were lower this time, and instead of ascending in tone, they were descending in tone. And they were farther away, maybe a quarter mile to the east. It seemed that whatever this thing was, it was moving away. It vocalized a few times and then went quiet. Somehow this relaxed me a little. The third recording in the thread linked at the top of this report captures these vocals, and again, my ears only picked up the loudest of the vocals. The recorder captured more, including wood knocks. It's also interesting that at 23 seconds there is a very soft, low vocal and at 25 seconds a much louder, clearer vocal. They sound like different voices, as if two speakers are interacting with each other.
Not long after this I decided it was time to turn in. I climbed into the back of my SUV and soundly locked all the doors. But try as I might, I could not get to sleep. For hours I tossed and turned and imagined that I could hear footsteps outside my vehicle. Twice I had to get out to use the bathroom, and doing so at 5 a.m. was a real exercise.
Eventually the sun came up though, and I was none the worse for wear. I packed up my audio recorder, which was fine at 5 a.m., but dead by 7 a.m. (the temps had dropped below freezing and possibly drained the battery). I was driving away at 7:15 and picked up the parabolic from its location on the way out. It too was dead despite having a lithium battery.
Since getting back home I've been trying to isolate those sound you hear above, and skim through the rest of the audio for any other vocals. My initial impression, which needs closer scrutiny to verify, is that something did come check me out at around 3 or 4 a.m., if the single wood knocks in close proximity to my camp are any indication (I hope to post more on this later). And the parabolic mic seems to have had some luck as well, including a series of low moaning barks in the middle of the night.
As a final interesting aside, I think if you pay close attention to the vocals in the third recording, it becomes evident why some of the old timers called these things yahoos.
The first is a couple of loud owl hoots that came in response to some vocals and wood knocks I had made. I respond to the hoots with one vocal bark and three rock clacks. I wood knock is audible at the 20 second mark:
http://sites.google.com/site/mongahela/myrecordings2010-1/WS310073-1OwlHoots-CMNRLPAM-Detail.mp3
Some time later, in the second recording, a series of whoops has started up on the hill above me. I can't hear the early whoops in this recording at the time, and only heard the loudest whoops at the very end of the recording as I sat by my campfire. The vocal at 1:19 is punctuated with a wood knock:
http://sites.google.com/site/mongahela/myrecordings2010-1/WS310073-2AudibleWhoops-CMNRLPAM-Detail.mp3
In the third recording the vocals have turned from whoops into downward "woos" and are farther away from camp. Again, only the loudest of these were audible at the time. Vocals at 0:23 and 0:25 seconds seem to be from two different speakers. A wood knock is audible at 0:26:
http://sites.google.com/site/mongahela/myrecordings2010-1/WS310073-3DistantWhoos-CMNRLPAM-Detail.mp3
Trip Report...
On March 20th I wanted to see if the snow had melted enough that I could gain access to the research area where I recorded wood knocks for the first time, last August. I was about ten miles short of my destination when the road became impassible with deep snow left from the February "double whammy" storms that hit this part of the east coast.
So I turned to my plan B, a visit to the location where I heard (but did not record) a single wood knock as I stepped from my vehicle last September. This area is about 15 miles away from the first, but 1000 feet lower in elevation and less likely to be snowed in. But I was wrong about that.
When I arrived at my destination, I found the last half mile to be about 8 inches deep in snow. No one had driven on the snow since it fell 7 weeks ago, and only one set of boot tracks were laid down, going in, but not coming out. I parked my truck and decided to hoof it in to where I wanted to camp, check out the area, see if I could drive all the way in, etc.
I turned on my recorder before my vehicle came to a stop. I parked next to a truck with Georgia tags, apparently belonging to the boot prints that went hiking down the road ahead of me. I got my gear together and started following those tracks south, into my destination.
Along the way I was trying to listen to my surroundings. I heard a loud wood pecker from time to time. Then I thought I heard a loud bark. I stopped and listened, but nothing. I continued on and some time later, heard a loud bark again. This wasn't my imagination. It was loud enough to overcome the noise of my own hiking filling my ears. But I couldn't tell what direction it came from, it was just too indistinct. I did a lot more hiking that day, about 5 miles all together, and heard similar barks from time to time, but could never nail down their source. I should have some of them captured on audio, and will have to spend some time later to isolate them.
As I reached my turn around point, the bitter end of the driveable road where some partiers had built a fire ring, I noticed the loan hiker's boots continued on along a marked hiking trail that followed a stream down the valley. Later in the day I would follow those tracks. That guy covered some ground.
I ate my lunch by the fire ring and listened quietly. There was nothing loud enough for my ears to pick up, no more barks, but a cursory review of my audio recordings seem to have captured some possible vocals and wood knocks. Again these will bear further scrutiny (I used two recorders that weekend and have 26 hours of audio to plow through).
After lunch I picked up my gear and hiked back out to my truck. I decided the parking location of my truck was a great place to deploy my new parabolic mic for its first field trial. I went north from my truck and dropped down over the roadside and into the woods about 50 feet. I propped the parabolic up on a tripod against a fallen tree and pointed it out over a deep valley and at the ridge a half mile to the north east. This was pointing away from the area I would camp in, and would hopefully capture sounds that I wouldn't hear from camp. My camp position was in the next valley to the south and behind the ridge where I had parked.
Back at the truck I put it in 4 wheel low and carefully made my way up the snowy lane. I had tested the depths and thought with a little luck I should be able to make it through the worst. Halfway through my driving ordeal I look up the road to see the loan hiker returning. He stopped to say hi, I admitted that I was the second set of tracks he saw. Before I could ask if he'd heard or seen anything he seemed in a hurry to move on, so I ended the conversation and plowed ahead.
I got to my camp location at about 2 p.m. and had plenty of time to hike and scope out the local area. I went downstream following the hiker's boot tracks in the snow. After a half mile his tracks kept going, but I didn't. I heard another bark while I hiked back to camp and decided to head down another trail that went into the next valley to the south. I squirrel hunted this valley last fall and saw bear sign there. I was familiar with what I was seeing but wanted to scope it out as a potential recording location. Unfortunately, due to all the snow melt, a roaring stream was running down this valley and completely drowning out any other sounds (an issue the valley I camped in did not have).
I got back to my camp at about 5:00 p.m. and decided to drive out for a dinner at one of my favorite local restaurants. I returned to my camp as the sun was going down and then got down to business. I double checked the parabolic mic on the way in. It was doing fine and recording for all it was worth.
At my camp I parked about 40 feet away from the fire ring in a nice level spot and next to a small boggy area. I was in the center of a narrow valley, about 100 yards wide, and equidistant between the bases of the two ridges that framed the valley between them. The ridges and valley ran east to west, with downstream being to the east. I was at the head water, or western end of the valley. The ridges to the north and south of camp were about 100 feet higher in elevation than my campsite in the valley floor. The nearest houses were 2 miles as the crow flies to the north, three ridges and three valley's away.
As the sun set I put together a campfire and pulled out my camp chair. The audio recorder was hanging in a small tree, near my truck and away from me. But even at that distance, the sensitive mics easily picked up every little sound I made.
The night was mostly clear and a crescent moon would be setting in about four hours. While it lasted I had periodic moonlight illuminating the splotches of snow under the trees around my camp, except for the ridge to the north which was cloaked in dense red spruce evergreens. Unlike the first time I camped alone, last year, I was not feeling quite so unsettled. This was certainly a creepy camp location, but the fire kept things lit up well and I was pretty comfortable.
At about 8 p.m. it was full dark and I started to make a few wood knocks, then some bark-like vocals, then a few rock clacks, and some whistles. I tried not to over do it. I would leave long pauses of space between each of the sounds that I created. I'd been doing this for about an hour or so when I heard two loud owl hoots from the northwest, upstream and toward where the parabolic dish was located a half mile away. They were pretty loud and sounded very owl-like. I had no reason to doubt they were an owl but they did raise my suspicion a bit. So I responded to the owl hoots with a single bark vocal and then three rock clacks. You can hear this in the first recording in the thread linked at the top of this report. (You can also hear a wood knock at the 20 second point, after my bark and before my rock clacks. And no, I didn't make that wood knock).
I heard nothing more so after a bit I went to my truck, got out a beer and a little laptop computer I travel with. I sat down next to the fire and turned my back to the thick forest on the north ridge (the ridge to the south was forested in deciduous trees, but blocked form view by more conifers around my camp).
I was writing happily on an audio recording "howto" that I intend to share here on the forum. It had been about 45 minutes or so since the owl hoot, and then I heard it...
Up on the ridge behind me, maybe a couple hundred yards away, I heard a low "woo" start up and then a second, immediately followed by a hollow wood knock. The affect on me was immediate. Every bit of my senses were focused on that sound. I stopped my typing and listened keenly as two more, louder but short woos came down from the woods above. They had an eerieness to them that told me, "this is no owl", and I smiled to myself as the hair on my arms, neck and head all stood on end.
It was an involuntary smile really, but I think it was in response to the knowledge that I was experiencing for the first time an effect that has been described by so many people on this forum. I felt it was a sort of initiation.
The vocals I heard are captured in the second recording listed in the thread linked at the top of this report. After listening to the recording, it was interesting to find that the recorder captured several low woos and a couple of wood knocks which I could not hear at the time. It wasn't until the final, loudest vocalizations, that I was even aware something was up there. The recording also reveals a wood knock right in the middle of one of the vocals.
I listened intently for more vocals, but nothing else came. Somehow my mind jumped to the conclusion that these woos and the earlier owl hoots were connected, and that my vocalizations and knocks had brought this thing closer to my camp, where I was camped alone, and where no one knew of my location, in an area that had been snowed in for two months until I drove into it. With all that rushing through my mind, I just couldn't bring myself to voice a response to those vocals. I thought the risk of drawing this thing in even closer was just too great given my singular vulnerability.
Hindsight being 20/20, I probably should have made a vocal, just to let it know that I knew it was there. But that kind of reasoning didn't enter the equation. Whatever that thing was, I'm sure it knew I was down there. My campfire smoke filled the top end of the valley and the firelight would have been visible at great distance, even through those dark spruce forests.
I just stayed hunkered in my seat, not moving, just listening. Eventually, after hearing no approaching foot steps behind me, I went back to typing. I kept an ear out for more sounds, but relaxed enough to get my head back into what I was writing. It was some time later, maybe 15 minutes, when I heard the vocals again.
They were lower this time, and instead of ascending in tone, they were descending in tone. And they were farther away, maybe a quarter mile to the east. It seemed that whatever this thing was, it was moving away. It vocalized a few times and then went quiet. Somehow this relaxed me a little. The third recording in the thread linked at the top of this report captures these vocals, and again, my ears only picked up the loudest of the vocals. The recorder captured more, including wood knocks. It's also interesting that at 23 seconds there is a very soft, low vocal and at 25 seconds a much louder, clearer vocal. They sound like different voices, as if two speakers are interacting with each other.
Not long after this I decided it was time to turn in. I climbed into the back of my SUV and soundly locked all the doors. But try as I might, I could not get to sleep. For hours I tossed and turned and imagined that I could hear footsteps outside my vehicle. Twice I had to get out to use the bathroom, and doing so at 5 a.m. was a real exercise.
Eventually the sun came up though, and I was none the worse for wear. I packed up my audio recorder, which was fine at 5 a.m., but dead by 7 a.m. (the temps had dropped below freezing and possibly drained the battery). I was driving away at 7:15 and picked up the parabolic from its location on the way out. It too was dead despite having a lithium battery.
Since getting back home I've been trying to isolate those sound you hear above, and skim through the rest of the audio for any other vocals. My initial impression, which needs closer scrutiny to verify, is that something did come check me out at around 3 or 4 a.m., if the single wood knocks in close proximity to my camp are any indication (I hope to post more on this later). And the parabolic mic seems to have had some luck as well, including a series of low moaning barks in the middle of the night.
As a final interesting aside, I think if you pay close attention to the vocals in the third recording, it becomes evident why some of the old timers called these things yahoos.
Monday, March 1, 2010
Using Spectrograms To Get Even More Out of Your Audio Recordings
Last year I began paying a lot of attention to the various audio recordings of potential sasquatch vocalizations that are available on the internet. And while I have a fairly practiced ear when it comes to audio analysis, I had a sneaking suspicion there is more to these recordings than normally meets the ear. So I set about finding tools that could help me take a closer listen to, and look at, some of these recordings.
The first thing I learned was some new tricks from an old friend, Audacity. I found that with some judicious post processing, as described in this post, I could clean up a lot of noisy recordings and uncover previously obscured or inaudible sounds. The second thing I found was that your ears work better when your eyes are involved. So to "visualize" the sounds captured in an audio recording I looked into spectrograms, and found a free, open source application with audio analysis at its core. Sonic Visualiser (http://www.sonicvisualiser.org/ ) is one of a collection of audio applications capable of generating spectrograms, but in terms of capability and configurability, it's very hard to beat. And the the price is certainly nothing to sneeze at.
The thing that makes Sonic Visualiser so appealing to me, its capability, also created a learning curve that took me a few weeks to work through. But the value of this type of tool, even for the simple act or reviewing your audio recordings, is so immense that I found it well worth the effort. And because I believe this tool can fundamentally change the way you will look at your field recordings, I'm willing to write this direct "how-to" to help you get up and productive with this software as quickly as possible.
Why do this? Because listening to hours of field recordings on the off chance that something catches your ear has become a pitiful activity. Your time is better spent examining the sounds you've captured, and this tool will help you find the sounds you would never have known were there. With spectrograms you'll not only be able to scroll through hours of "visual" audio in much less time than it takes to play it, you'll actually begin to recognize patterns that tell you what kind of sound you've captured, before you even listen to it. So enough hyperbole, let's get to it...
Begin by downloading Sonic Visualiser from the download page at the link above and installing it on your computer. You don't need anything super powerful to run this, but a computer bought within the last couple of years will give you the most satisfactory graphics performance (this is a visual application after all). Older computers will work as well, but with diminishing performance as age increases (hmmm, sounds familiar).
Once Sonic Visualser (SV for short) is installed, you'll want to start it and then open your first audio file. Choose something short for these exercises, just till you get the hang of things. Go to the File menu and select the "Import Audio File" option. In the resulting window navigate to the file you wish to listen to, select it, and click Open.
The file will open in SV's default view, the well known spectrum image. This adds little value to our exercise so click the 'X' in the upper left corner to close that spectrum window. Your audio file will remain loaded, but we're going to view it in a different form, as a spectrogram.
On the keyboard hit the "G" key, which is a short cut to the "Pane>Add Spectrogram" menu item. This will open a spectrogram view of your audio file.
First thing to do is notice the panel on the right of your screen, that's where you'll make all the tweaks to your spectrogram (the configurability I referred to above).
Start by clicking on the tab labeled #2, that will overlay a time grid on your spectrogram. Use the "up" arrow on your key board to zoom in on your file. I normally zoom in until I can see the individual seconds of the file. This zoom will give you good fidelity on the signals that are visible in your spectrogram.
But notice how difficult it is to distinguish the colors of this "default" lime green spectrogram. We can improve this by clicking on tab #3 and from there selecting the drop down menu next to the "Colour" option. You'll see a number of "themes" in the drop down, and eventually you should play with them all and find your favorite. But for now, let's choose my favorite, "Fruit Salad". I know the result is garish at best, but we can make one more tweak to improve that. Just below Colour, select the drop down menu next to "Scale" and choose the dBV^2 settting. This will give you an image with the quiet areas of your recording painted in blue, and the louder portions of your recording painted in increasingly warmer colors (red being the loudest).
Now look at the left hand edge of the spectrogram window. You'll see a range of numbers, high at the top, low at the bottom. These are the frequencies, represented in Hertz, that were captured by the audio recorder that made your recording. From my experience, we'll find most of the sounds we're interested in below 2500 Hertz. So to focus in on that area look in the lower right corner of the spectrogram and note the two short, vertical columns stacked on top of the horizontal bar. (If this is not readily obvious, click the Z key on your keyboard repeatedly. This will toggle the columns on and off. You want them on.) Once you've spotted them, use your mouse to double click the left column. This pops up a window where you can specify the range to view. I leave the first number at its default (the lowest frequency), and change second number to 2500. Click OK and the image will zoom in. 2500 Hertz will be the top number on the left hand edge of the spectrogram.
This is a good spot to give your file it first playback. Easiest way to do that is hit the space bar to start playback (and hit it again to stop). You can also use the buttons on the top menu bar, which should look familiar to you.
As the file plays, watch the vertical bar move left to right across the spectrogram. As it crosses over the "hottest" colors in your file, you'll hear the sound that the color represents. The bright red colors are obvious, and probably easily heard through your computer speakers. But notice all those "warm colors", the oranges and yellows. Those are sounds too. If you pay attention as the vertical bar scrolls over them, they may pop out and become more audible. This is the coordination of eye and ear working together. The eye focuses your attention and the ear picks up the sounds. The more files you listen to, the tighter this eye-ear coordination becomes.
If you focus on a specific blob of color, notice it's relative vertical position. If it's closer to the top of the image, its a higher pitch sound that your ear should listen for. Conversely, colors at the lower edge are low frequency sounds. This is important to remember because often you'll have overlapping sounds, some high and some low, but a spectrogram can clue you in to their existence (where one might normally obscure the other fainter sound). Eventually, once you can see that two or more sounds exist at one point in time, you'll be able to filter out the louder sound and hear the fainter sound in the background. (Doing this without a visual queue can take a lot of focus thought. This is where spectrograms really start to shine).
That's it, you have the basics down and from here you can do all kinds of experimentation. But before you do, you should save your settings before going farther (or closing the file). That's because SV doesn't automatically keep your settings for you. Every new file you open will have to go through these set up steps (a real hassle if you want to listen to the same file more than once, and who doesn't?). So go to the File menu and select "Save Session As". Enter a file name in the resulting window and click save (try to save this new ".sv" session file in the same directory as the audio file, for convenience's sake).
A couple other things worth touching upon before we go, though.
First, use the left and right arrow keys on your keyboard to scroll forward and backward in your audio file. Hitting the left arrow is a quick way to repeat a sound that you want to "loop".
Second, hitting the "T" key on your keyboard will add a new tab to the panel on the right. When that tab is on top you can click on the spectrogram and enter text labels to next to the sounds you hear. This is a great way of noting neat sounds that you want to come back to, or to highlight for other people who use SV. You can also export all those notes as text, with their time location in the file, and share them in an email.
Third, hitting the "X" key will make the panel on the right disappear, giving you a wider spectrogram to view.
Fourth, everything's better with headphones. If you really want to hear what's going on in your audio recordings, you'll absolutely need a decent set of closed, over the ear head phones (Sennheiser has two or three models from $25 up to $100 or so). Some in-ear head phones might work too, if you can deal with the discomfort.
Finally, to get a real feel for how useful spectrograms are for rapid review of large audio files, load up a big file (preferably something that has been post processed as described in the post above) and scroll through it with the arrow keys. When you see a bright blob on your screen stop, and play through it. When you see a faint blob stop and listen to that, too. That's where the real surprises begin to appear, in the faint signals that your ears normally would have never noticed.
Good luck.
The first thing I learned was some new tricks from an old friend, Audacity. I found that with some judicious post processing, as described in this post, I could clean up a lot of noisy recordings and uncover previously obscured or inaudible sounds. The second thing I found was that your ears work better when your eyes are involved. So to "visualize" the sounds captured in an audio recording I looked into spectrograms, and found a free, open source application with audio analysis at its core. Sonic Visualiser (http://www.sonicvisualiser.org/ ) is one of a collection of audio applications capable of generating spectrograms, but in terms of capability and configurability, it's very hard to beat. And the the price is certainly nothing to sneeze at.
The thing that makes Sonic Visualiser so appealing to me, its capability, also created a learning curve that took me a few weeks to work through. But the value of this type of tool, even for the simple act or reviewing your audio recordings, is so immense that I found it well worth the effort. And because I believe this tool can fundamentally change the way you will look at your field recordings, I'm willing to write this direct "how-to" to help you get up and productive with this software as quickly as possible.
Why do this? Because listening to hours of field recordings on the off chance that something catches your ear has become a pitiful activity. Your time is better spent examining the sounds you've captured, and this tool will help you find the sounds you would never have known were there. With spectrograms you'll not only be able to scroll through hours of "visual" audio in much less time than it takes to play it, you'll actually begin to recognize patterns that tell you what kind of sound you've captured, before you even listen to it. So enough hyperbole, let's get to it...
Begin by downloading Sonic Visualiser from the download page at the link above and installing it on your computer. You don't need anything super powerful to run this, but a computer bought within the last couple of years will give you the most satisfactory graphics performance (this is a visual application after all). Older computers will work as well, but with diminishing performance as age increases (hmmm, sounds familiar).
Once Sonic Visualser (SV for short) is installed, you'll want to start it and then open your first audio file. Choose something short for these exercises, just till you get the hang of things. Go to the File menu and select the "Import Audio File" option. In the resulting window navigate to the file you wish to listen to, select it, and click Open.
The file will open in SV's default view, the well known spectrum image. This adds little value to our exercise so click the 'X' in the upper left corner to close that spectrum window. Your audio file will remain loaded, but we're going to view it in a different form, as a spectrogram.
On the keyboard hit the "G" key, which is a short cut to the "Pane>Add Spectrogram" menu item. This will open a spectrogram view of your audio file.
First thing to do is notice the panel on the right of your screen, that's where you'll make all the tweaks to your spectrogram (the configurability I referred to above).
Start by clicking on the tab labeled #2, that will overlay a time grid on your spectrogram. Use the "up" arrow on your key board to zoom in on your file. I normally zoom in until I can see the individual seconds of the file. This zoom will give you good fidelity on the signals that are visible in your spectrogram.
But notice how difficult it is to distinguish the colors of this "default" lime green spectrogram. We can improve this by clicking on tab #3 and from there selecting the drop down menu next to the "Colour" option. You'll see a number of "themes" in the drop down, and eventually you should play with them all and find your favorite. But for now, let's choose my favorite, "Fruit Salad". I know the result is garish at best, but we can make one more tweak to improve that. Just below Colour, select the drop down menu next to "Scale" and choose the dBV^2 settting. This will give you an image with the quiet areas of your recording painted in blue, and the louder portions of your recording painted in increasingly warmer colors (red being the loudest).
Now look at the left hand edge of the spectrogram window. You'll see a range of numbers, high at the top, low at the bottom. These are the frequencies, represented in Hertz, that were captured by the audio recorder that made your recording. From my experience, we'll find most of the sounds we're interested in below 2500 Hertz. So to focus in on that area look in the lower right corner of the spectrogram and note the two short, vertical columns stacked on top of the horizontal bar. (If this is not readily obvious, click the Z key on your keyboard repeatedly. This will toggle the columns on and off. You want them on.) Once you've spotted them, use your mouse to double click the left column. This pops up a window where you can specify the range to view. I leave the first number at its default (the lowest frequency), and change second number to 2500. Click OK and the image will zoom in. 2500 Hertz will be the top number on the left hand edge of the spectrogram.
This is a good spot to give your file it first playback. Easiest way to do that is hit the space bar to start playback (and hit it again to stop). You can also use the buttons on the top menu bar, which should look familiar to you.
As the file plays, watch the vertical bar move left to right across the spectrogram. As it crosses over the "hottest" colors in your file, you'll hear the sound that the color represents. The bright red colors are obvious, and probably easily heard through your computer speakers. But notice all those "warm colors", the oranges and yellows. Those are sounds too. If you pay attention as the vertical bar scrolls over them, they may pop out and become more audible. This is the coordination of eye and ear working together. The eye focuses your attention and the ear picks up the sounds. The more files you listen to, the tighter this eye-ear coordination becomes.
In this spectrogram of a 2009 audio recording from the BFRO expedition to the Olympic Peninsula, vocals audible to the unaided ear are the brightest colors on the chart. But fainter, inaudible wood knocks and vocals also become visually discernible, and subsequently audible, once the ear knows where to listen. These fainter signals might easily have gone unnoticed in a typical audio file review. (click image for larger view)
If you focus on a specific blob of color, notice it's relative vertical position. If it's closer to the top of the image, its a higher pitch sound that your ear should listen for. Conversely, colors at the lower edge are low frequency sounds. This is important to remember because often you'll have overlapping sounds, some high and some low, but a spectrogram can clue you in to their existence (where one might normally obscure the other fainter sound). Eventually, once you can see that two or more sounds exist at one point in time, you'll be able to filter out the louder sound and hear the fainter sound in the background. (Doing this without a visual queue can take a lot of focus thought. This is where spectrograms really start to shine).
That's it, you have the basics down and from here you can do all kinds of experimentation. But before you do, you should save your settings before going farther (or closing the file). That's because SV doesn't automatically keep your settings for you. Every new file you open will have to go through these set up steps (a real hassle if you want to listen to the same file more than once, and who doesn't?). So go to the File menu and select "Save Session As". Enter a file name in the resulting window and click save (try to save this new ".sv" session file in the same directory as the audio file, for convenience's sake).
A couple other things worth touching upon before we go, though.
First, use the left and right arrow keys on your keyboard to scroll forward and backward in your audio file. Hitting the left arrow is a quick way to repeat a sound that you want to "loop".
Second, hitting the "T" key on your keyboard will add a new tab to the panel on the right. When that tab is on top you can click on the spectrogram and enter text labels to next to the sounds you hear. This is a great way of noting neat sounds that you want to come back to, or to highlight for other people who use SV. You can also export all those notes as text, with their time location in the file, and share them in an email.
Third, hitting the "X" key will make the panel on the right disappear, giving you a wider spectrogram to view.
Fourth, everything's better with headphones. If you really want to hear what's going on in your audio recordings, you'll absolutely need a decent set of closed, over the ear head phones (Sennheiser has two or three models from $25 up to $100 or so). Some in-ear head phones might work too, if you can deal with the discomfort.
Finally, to get a real feel for how useful spectrograms are for rapid review of large audio files, load up a big file (preferably something that has been post processed as described in the post above) and scroll through it with the arrow keys. When you see a bright blob on your screen stop, and play through it. When you see a faint blob stop and listen to that, too. That's where the real surprises begin to appear, in the faint signals that your ears normally would have never noticed.
Good luck.