Here is a single line with the default line thickness. The corresponding sound is a sinusoid which drops in frequency as the line goes downward to the right. The text in the picture below also shows the parameters used to create the sound which are extracted from the picture by the line2sine program.
You can make a sinusoid louder by increasing its thickness. The default thickness is 0.035 (cm), while the thickness of the line below is 0.2457. The maximum amplitude of all sinusoids at any given time cannot excede 1.0 units; otherwise, the sound will be clipped.
You can also control the amplitude envelope of a line by placing an envelope string in the line's label. This label can be given a width of 0 to hide the amplitude envelope in the picture. The envelope applied to the line below is a triangle envelope. It has a maximum of 1 at the middle, and tapers linearly to 0 at each end.
A line can have any number of segments:
Note that any changes in time direction will cause the line vertices to be resorted into proper time order. The picture below has one line which first goes forward in time, then backward in time; therefore, the line will be sorted so that the vertices will be arrived at forward in time. Listen to the sound to see what happens.
See the manual for more information.
Here are some more examples.