Types of waveform

This video just has a plain transcript, not time-aligned to the videoAs we have already seen, waves can be either simple or complex. A simple wave be described by the mathematical sine function showing a simple oscillation. A complex wave is made up of at least two sine waves added together.
Waves may differ in their complexity, while sharing a fundamental frequency. For example, both the complex red wave and the simple blue wave have an F0 of 100 Hz
The specific shape of a complex wave may not affect our perception of the pitch of that sound, but it does effect the overall quality.
Each of the waves here differ in their complexity, but all have the same F0.
While simple waves are always periodic, meaning that they repeat at regular intervals, complex waves may be either periodic or aperiodic
Complex periodic waves have a repeating pattern, and we can use that pattern to calculate the fundamental frequency.
Complex aperiodic waves do not have any pattern to their oscillations, and therefore will not have an F0.
Complex waves may also be either continuous or transient.
Transient waves are always aperiodic, while continuous waves may be either periodic or aperiodic.
Here we have examples of continuous and transient waves both in speech and non-speech. in the upper left we have a continuous wave represented a continuous oscillation of a vowel.
In the lower left, we have continuous aperiodic wave represented white noise.
In the upper right we have a transient aperiodic wave representing the strike of a hammer.
And in the bottom right, we have a transient aperiodic wave representing the burst of an unaspirated [t].
We can use these concepts of periodic, aperiodic, transient and continuous to describe major classes of speech sounds in the waveform.
For example, this waveform of a man saying “scan it” is made up of an aperiodic continuous sound, followed by a transient sound, followed by three periodic continuous sounds with different complexities, and finished by another (low amplitude) transient sound.
These various sound waves correspond to major classes of speech sounds, namely fricative, plosive, vowel, and nasal. As a result, the waveform of “Scan it!” is visually similar to the waveform of “Spoon up!”, which is made of the same major classes in the same order.