Steps to reproduce:
1. Open attached project
2. Select "Timeline" object and in the Timeline editor window press play to listen to the music track
3. Select the music in the bottom audio track
4. Set the speed Multiplier to 2 and observe the audo clip duration being halved
5. Press play on the timeline editor
6. The music plays half the duration, but does not play at double the pitch
7. Enter Unity Play mode, music plays as expected at double the pitch and half the duration

Expected: Since the duration immediately reflects the new speed multiplier of the audio clip, the pitch should also immediately be audible
Actual: It take sometimes 2 or 3 tries of playing it through the timeline editor, or just entering play mode to hear the actual change in pitch

Reproduced on:
Version 2019.3.0a4 (7368acd360f4)
Tue, 21 May 2019 18:40:41 GMT
Branch: trunk

2019.2.0b5, 2019.1.6f1, 2018.4.2f1