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Tracks
Track Layout
Tracks show the actual sound waveforms or spectrograms. Getting to know
how to work with tracks in central to using Thinklabs Phonocardiography
for working with heart sounds or lung sounds. The basic anatomy of a
Track is shown above:
Track Menu - Provides options
for manipulating each Track. See Track Pop-Down Menu. Click the Playback Select button to select
which Track to Play. Playback Select will be bright cyan for the
selected playback Track.
Waveform Track - Shows the
actual heart sound or lung sound time domain waveform. It is possible
to scroll to any position along the time axis, or zoom in or out to
look closely at one section or larger portions of a waveform. Note that
the color scheme can be changed on the Thinklabs Menu to show a bright
blue waveform on a dark background (Dark Color Scheme) or a dark
waveform on a white background (Light Color Scheme).
Label Track - The Label Track
provides a place to annotate events along the time axis such as S1, S2,
S3, murmurs, etc. Label Tracks can be added or deleted as required
using Project > Add Label Track to add a Label Track, and X to
delete the Label Track. Note that if a span of time is selected first,
the whole span can be labelled. This allows you to select an entire
duration of a murmur, for example, and then label it. If you then click
on the Label, it will immediately highlight the entire span.
Track Name - Every Track can be
uniquely named. When Importing a Sound File, it will take the name of
the file. If you Record a new recording, you must give it a name via
the Track Pop-down Menu.
Track Control Area - The Track
Control Area provides information about the Track(s) and allows for
control of editing and playback. At the top of the Area are the details
of the file you are working with. It is either Stereo or Mono. The
Sampling Rate is also shown. High Quality audio requires 44100Hz
Sampling Rate. You can use a lower sampling rate, but if you wish to
record CD's, use 44100Hz. Below the Stereo/Mono is the data format.
About Stereo or Mono Tracks -
Usually, you do not need Stereo for heart sounds or lung sounds
recorded from the stethosope. If you used an iPod for recording, one
channel will probably be blank and you only need the Left Channel. If
you have Imported a Stereo Track, use the Track Pop-Down Menu to first
Split Stereo to Mono, and then delete the blank track using the X in
the top left corner.
Controlling and Editing Tracks
Tracks or parts of tracks can be selected for Playback or Editing as
illustrated here:
Playback - You must select
which track you would like to hear when the PLAY button is clicked. You
do this by clicing "Playback Select" (turning it bright Cyan/turquoise)
in the Track Control area as shown below.
Volume - The Slider just below
"Playback Select" controls the Volume of the track playback. There are
also other places to control volume (a) Mixer Toolbar, and (b) In
Windows on the Audio Controls. (If sounds are too quiet, consider using
the Amplify function on the Thinklabs Toolbar to Amplify a track.)
Editng a Whole Track - An
entire track, or part of a track, can be edited (Amplify, Filter, Tempo
Change, .deleted, copied, etc.). To select the entire track for
editing, Click anywhere in the Track Control area, as shown below.
Notice that the COLOR of the Track Control area is GREY for a track
that is selected for editing, and the portion of the track itself that
will be edited also turns grey.
Editing Part of a Track - To
select a portion of a Track to edit, DRAG your mouse ACROSS the portion
you wish to edit. It will turn Grey as shown below. If you wish to
select a new portion, simply redo the drag operation:
The Dispay view can show waveform, spectrum, or both. The above image
shows both waveform and spectrum. It is generally faster to locate
sections of interest using waveform only view, and then switching to
waveform + spectrogram when a region of interest is in view. Turning
Spectrogram on of off can be done using the Thinklabs Toolbar Display
button, or the Toolbar Pulldown Menu.It is also possiblt to show
Spectrogram only.
Spectrum View
Spectrum Only view is selected on the Track Pop-Down Menu (see below)
and shows the Spectrogram only. Note that resolution of the Spectrogram
can be adjusted via Edit > Preferences > Spectrogram. Using a
higher resolution requires a faster computer.
Name... - lets you change the name of the track. Importing a
Track will name the Track to the file name. Recording will not name a
Track - you must name it using this Menu selection.
Move Track Up - exchange places with the track above this
one.
Move Track Down - exchange places with the track below this
one.
Waveform - sets the display to Waveform - this is the default
way of visualizing audio.
Spectrum - display the track as a spectrogram, showing the
amount of energy in different frequency bands. Shoing the Spectrum
requires a fast computer. It is better to zoom in to the view you want
and then show spectrum, rather than panning and zooming with Spectrum
on.
Waveform and Spectrum - display both waveform and
spectrogram. Can achieve this on ALL tracks at once by using the
Display button on the Thinklabs Toolbar. See notice above on Spectrum
and computer speed.
Split Stereo To Mono - when you Import a Track, if it is a
Stereo recording, both Channels/Tracks will show (left and right). For
phonocardiography use, the second track is redundant or blank. Once you
Import a track, Click Split Stereo to Mono, and it will split Left and
Right. Then DELETE the redundant track (X in the top left corner of the
track).
Label Tracks can be used to annotate an audio Track. They can be
used to label S1, S2, S3, S4, murmurs, and even save selected portions
of a sound.
Label Tracks are generated automatically when you Import a sound
file. You can then delete the Label Track by clicking X in the left
corner of the Label Track.
To create a new Label Track, select New Label Track from the
Project Menu.
Alternatively, simply
click or select where you would like to place a label, and choose
Add Label at Selection from the Project Menu,
and a Label Track will be created automatically if one doesn't already
exist.
To add a new label, click or select where you want the new label to
appear,
then select Add Label at Selection from the
Project Menu,
then type the name of the
label, and finally press Enter or click outside of the label.
In addition, you can use the Add Label at Playback Position command
from the Project
Menu if you want to
add a label at a certain place while you are listening. By default,
this
command has a shortcut of Control+M.
To edit the name of a label, click anywhere in it.
Zoom in first if there are too many labels crowded together and you
are unable to click on the one you want. When a label is selected
for editing, it looks like the S2 label below:
When editing the name of a label, you are limited to using just
the backspace key for editing. There is currently no way to move the
insertion point to append a letter to the beginning of a label.
Once a label is selected, you can move to the next label by pressing
Tab, and move to the previous label by pressing Shift-Tab.
To delete a label or multiple labels, select the area containing the
label flags you wish to delete, and choose Silence from the
Edit Menu.
Alternatively you can delete
an individual label by clicking on it and pressing Backspace until you
have deleted all of the characters in the label, then pressing Enter.
To move labels, use the normal editing commands like Cut, Copy,
Paste, Delete, and Silence.
You can save a selection in a label. When you create a new
label, the left selection edge determines the position of the label's
flag. However, the right selection edge is also stored in the label,
and when you click on it, the full original selection will be restored.
If you wish to apply this selection to only a subset of the tracks,
shift-click in the label area to the left of each track's waveform
to change whether each track is part of the selection or not.
Exporting and Importing label tracks
Label Tracks are saved when you save an Audacity Project, so if you
just want to continue using the labels along with the same file,
just save a project. But you can also export the labels to a simple
text file, and import them. This allows you to save information about
the locations of events in an audio file for use in another program,
and also provides a way to mass-edit the labels if necessary.
To export a Label Track, choose Export Labels... from the
File Menu. The
exported file will
contain one line per label, starting with the time offset in
seconds, then a tab, and then the name of the label, for example:
1.217995 Bass intro
3.921073 Guitar enters
7.584454 Drums enter
11.070002 Chorus
To import a Label Track, choose Import Labels... from the
File Menu.
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