Answer: The absolute phrase of "Music blaring, the car sped down the highway on the way to the beach" is "music blearing".
Explanation: An absolute phrase is a phrase that usually contains a noun and a participle. Moreover, it can also include modifiers and/or objects. An absolute phrase is generally placed at the beginning of a sentence and it is always separated from the rest of the elements by means of a comma. In the sentence provided, "music blearing" is the absolute phrase because it contains a noun ("music") and a participle ("blearing"). Furthermore, it has been placed at the beginning and it has been separated from the rest of the sentence.