A low note keeps sounding while the chords above it change. The bass seems still, yet the passage does not feel motionless. Its relationship with the upper notes keeps changing: comfortable in one moment, more unsettled in another.
That is a useful entrance to hearing a pedal point. In a common form, a pitch is held or repeated through a changing harmonic setting, including moments when it is not a member of the chord above.
Listen to the fixed note and the moving harmony separately
Music Theory for the 21st-Century Classroom explains a pedal point as a note sustained through changing harmonies, beginning as a chord tone before becoming a non-chord tone. It notes that bass placement is common, while higher-voice and double pedal points also occur.
On a keyboard, try a small illustrative sequence at a comfortable volume. Hold a low C while playing C–E–G above it. Keep the low C while changing the upper notes to G–B–D, then return to C–E–G. Listen to the continuing bass against each upper group rather than trying to make the example sound like a finished composition.
The low C belongs to the first upper triad but not the second. The changing relationship is the point of this exercise. If your instrument cannot sustain the bass for long, repeat it gently without changing its pitch.
Do not confuse the musical idea with a piano control
A piano’s sustain pedal can prolong many notes, but pressing it does not automatically create a pedal point. Conversely, a player can produce a pedal point without using that control. The term describes what a pitch does in the music.
When listening to a recording, choose a brief passage and follow only the lowest part first. Then listen again for the changing chords. Write a modest observation such as “the bass stayed on one pitch while the upper harmony changed,” and check it against a score when one is available.
A repeated melody or rhythmic pattern raises a different question from a single held harmonic anchor. Naming the fixed pitch helps you hear why a seemingly unmoving part can make the surrounding movement more noticeable.