Audio Track Dropdown Menu

Peter 31Jul15: ToDo-1 Paul's new menu structure requires documenting here once it has stabilized. This may turn out to be quite a big piece of work.

Gale 02Jun15: No mention of Spectral Selection menu items

• Peter 02Jun15: I updated the image and added terse entries for the Spectral Selection views. Removed the P1.

The Audio Track Dropdown Menu is accessed by clicking in the Track Name, by the downward-pointing triangle in the Track Control Panel. Alternatively, you can access the Track Dropdown Menu on the currently focused audio track by pressing SHIFT + M. Use the Drop-Down to manipulate individual or stereo tracks: Rename a track Move a track up or down in the project window Set the current type of view for the track Set whether a track is mono, left channel or right channel Make or split stereo tracks Swap the channels of a stereo track Set the current sample rate and sample format for the track. There is no need to select the track before accessing the dropdown menu. To change the default type of track view with which a new project always starts, change "Default View Mode" in Tracks Preferences. To change the default sample rate and sample format with which a new project always starts, go to Quality Preferences.

Name...

Displays the "Track Name" dialog where you can give the track a new name. Useful in multi-track projects to provide a visual indication of the content of each track.

Moving Tracks

Any individual track can be moved up or down using the menu items.

• Move Track Up: Moves track up.
• Move Track Down: Moves track down.
• Move Track To Top: Move the track to the top of the project window.
• Move Track To Bottom: Move the track to the bottom of the project window.

It is often more convenient to just click in the Track Control Panel on the left of the track and drag the track up or down.

Waveform

This first half of this waveform is a "Chirp" tone which stays at the same amplitude (loudness), as shown by the horizontal top and bottom. The linear scale on the left goes from +1 at the top (the maximum possible loudness without distortion when the signal is positive) to -1 at the bottom (the maximum when it is negative). The horizontal line centered on 0.0 is silence. What you can't see without zooming much further in is that the pitch of this tone is gradually increasing. Zooming would show the individual cycles in the waveform (the positive and negative peaks) occurring much closer together at the end of the sound. The second half of the waveform is the word "Audacity" spoken by a male voice.

This image is a waveform view of an extremely short chirp, one tenth of a second, with only a few cycles, where the pitch increases very rapidly. As it's so short, we can zoom in to show the closer spacing of the cycles as the frequency (and hence the pitch) increases from left to right.

Waveform (dB)

This is the same chirp and word as in the first Waveform image, but in this view the vertical scale is in dB. This is a logarithmic method of displaying the amplitude.

The dB range of the vertical scale is set in Edit > Preferences > Interface.

Steve 18Oct13: I don't believe this is true:
"It gives a better representation of the sound we hear,"
In the Waveform (dB) view, just about everything looks "really loud", which is not like the sound that we hear.
this scaling gives better detail for the fainter sounds.
but only down as far as the minimum dB specified in Preferences. In the case of this image,the minimum dB is -36, (which is not the default for Audacity). Any sound below this limit is not shown at all - again, this is not the way we hear. The default dB range is -60 dB.
It also shows more clearly than the waveform view how the energy of the "Audacity" word is naturally concentrated in the central "dac" part, and weakest at the end.
Generally it is very difficult to get any realistic idea of the sound from the Waveform dB view. The same "increase in density" can be seen in the standard Waveform view - probably more clearly than here.

Bill 21Jul14: I agree with Steve's 3 points above. So the question then becomes, what do we say (if anything) about why the dB view is included?

Steve 21Jul14: Martyn recently came up with a good reason for using the dB view. If recording with 24-bit hardware, (on a system that supports it properly), then you may well want to allow a lot more headroom, particularly if recording live musicians/singers. -20 dB peak is not uncommon for 24-bit recording. On the "normal" waveform view, that is hardly visible, but can clearly be seen in the "Waveform dB" view. I'm not sure this is worth mentioning in the manual until we have 24-bit hardware support on Windows. Gale 22Jul14: There is currently 24-bit hardware support for WASAPI loopback, but that's it. IMO the image should show the default -60 dB range unless there is reason to do something else, in which case the reason should be stated. So if you want to make the image have greater range than -60 dB so that it does show fainter sounds, that would be fine with me.

• Peter 02Feb15: I suspect that it is mainly a historical hangover, the dB view was already present in Audacity 0.98b. My understanding is that when Dominic was originally developing Audacity for his thesis his original objective was the visualization of the audio (he was doing computer music research at CMU under Roger Dannenberg) - the audio editing came as an add-on bonus as part of that, I believe. So maybe there isn't a real "why dB view?"
  • Peter 04Feb15: I removed the contentious wording and it's attendant P2.

    ToDo Px remains in case we want to add a "Why dB view"

Paul 04Feb15: In my opinion it would be adequate to restore one of the sentences and add one of Steve's: "This scaling gives better detail for the fainter sounds,

but only down as far as the minimum dB specified in Preferences." I often find that clicks still loud enough to be distracting are easily seen in this view without zooming the vertical scale. Mention too that piecewise exponential curves, such as the Envelope tool creates, appear as straight lines? That naturally decaying percussive notes also have exponential envelopes?

Visit the Audacity Waveform page for details and examples of the waveform views.

Spectrogram

Gale 14Sep14: Posting some "brain dump" material from Paul L that may help make this section more understandable in relation to Spectrograms Preferences.

• Every frequency band at -20 dB or higher appears white in default display settings. 0 to -20 dB is indistinguishably white, -100 and below is indistinguishably gray, and -40 is red, -60 magenta, -80 pale blue, with gradations between.
• Try generating sine waves with amplitudes 1, .1, .01, .001, etc. which correspond to those dB values. Each of those linear values is 20 dB lower, so 0 dB, -20 dB, -40 dB etc.
• It isn't explained that there are red, magenta, and pale blue colors evenly spaced along the dB scale between "Gain" and "Gain - Range". I figured that out by playing and later confirmed that is how the code also works.
• "Gain" is just where white gives way to pink and "Gain - range" is just where pale blue fades to gray.

This view of the same chirp and word shows how the amount of energy in different frequency bands changes over time. Higher frequencies are at the top of the scale, lower frequencies at the bottom. The blue color is the least energy and the red and white are the most. The progressive increase of pitch in the chirp tone is vividly demonstrated by the upward sloping diagonal line. Spectrogram view also confirms that the "Audacity" word has most energy in the middle of the word.

• Go to the Spectrograms Preferences to see the options for adjusting exactly how the spectrum is displayed.
• You can click in the Vertical Scale at any time to zoom in to a particular frequency range, or right-click to zoom out. Frequencies higher than half the sample rate of the track are not displayed because a given rate cannot contain higher frequencies than that.
• This tutorial in the Wiki shows how the Spectrogram view can be used to help track down and eliminate hard to find clicks.

Spectrogram log(f)

This view is the same as the Spectrogram view except that the vertical scale is logarithmic.

Visit the Spectrogram View page for details and examples of the spectrogram views.

Pitch (EAC)

Pitch (EAC) view highlights the contour of the fundamental frequency (musical pitch) of the audio, using the Enhanced Autocorrelation (EAC) algorithm.

The EAC Algorithm was developed to produce a mathematical representation of the changes of pitch in a piece of audio. The aim was to allow automated comparison of sound files so that two versions of the same tune could be recognized as being similar, even if played in different keys, or on different instruments.

When using Pitch view, go to Spectrograms Preferences and make sure that "Frequency Gain" is set to 0 or 1. Any other setting will make the Pitch view unusable.

Splitting and Joining Channels

• Mono, Left Channel and Right Channel Mainly used on each of multiple single channel tracks (ones that are not the split left and right channels of a stereo pair) to mix to a final stereo track. "Mono" feeds the output of that track to both left and right speakers on most two channel systems. "Left Channel" and "Right Channel" feed it only to that respective speaker. Currently Audacity does not support multi-channel playback.
• Make Stereo Track Use this command on the upper of two adjacent, single channel tracks which you want to join into one stereo track. The upper track always becomes the left channel of the new stereo pair and the lower the right channel, irrespective of whether each was mono, left or right before joining to stereo.
• Swap Stereo Channels Use this command on a stereo track to swap the left and right channels without having to split the stereo track (see below). The left channel and the right channel and will change places, so that the audible content of the left channel moves into the right and the audible content of the right channel moves into the left.
• Split Stereo Track splits the two channels of a stereo pair into separately editable tracks for left and right channels, left above the right. If you are mixing multiple single channel files, you might want to use the "Split Stereo to Mono" command noted below then use the pan slider on the Track Control Panel. This will give you more control over the pan than leaving the tracks as left and right channel.
• Split Stereo to Mono splits the two channels of a stereo pair into two separately editable mono tracks.

See Splitting and Joining Stereo Tracks for more details on using the Split Stereo Track, Split Stereo to Mono and Make Stereo Tracks commands.

Set Sample Format

Converts the sample format of the current track state to 16-bit integer PCM, 24-bit integer PCM or 32-bit floating point. The number of computer bits representing each sample in the waveform will be recalculated for the changed precision. Further edits will be performed at the new bit depth, but audio data for any track states before the conversion remains at its previous bit depth. This means that undoing the format change is always lossless.

Set Rate

Change the sample rate of the track, which can be thought of as the concentration of audio samples in the track or the time distance between them. Increasing the rate squeezes the existing samples into a shorter length (so increasing playback speed and pitch), while decreasing the rate spreads them out over a greater length (so reducing playback speed and pitch). This is useful for example if you import a file that has the wrong rate and thus plays at the wrong speed.

Changing the sample rate of a track without changing the speed involves resampling. Resampling for export is always done by changing the Project Rate in Selection Toolbar. To resample a track for use in the project, choose Resample in the Tracks Menu.