I haven't been able to find any footage or audio, but there are some pieces of info from some of the reviews.
Motor1: "Press the first power button ever fitted to a Porsche (yes, it’s left of the steering wheel for those Le Mans-style starts, duh), and a low-frequency thrum emerges. Switching to Sport Plus makes the sound more prominent inside, sending a phaser-like hum through the cabin during acceleration. While the exterior pedestrian warning sound is undeniably cool from the outside, the effect inside is thankfully defeatable within the Individual setting. (Like many party tricks, this one is initially cool but eventually overstays its welcome.) "
Whichcar: "The first thing you notice when on the move is that this electric car is hush-quiet but by no means totally silent. Instead, it hums up to 30km/h to warn stray pedestrians; above 50 it invites the wind, the tyres and the suspension to join an improvised and constantly varying jam session"
Top Gear: "Porsche of all companies knows that the noise is an important part of a car’s character. So the Taycan has its own signature sound. Not just the dreary pedestrian-warning low-speed synthesised hum, but a quite exciting cabin sound too. Wow. Sorry, that’s the best I can do to describe it: a heterodyning electro wow. It rises in pitch with speed, and in volume with power."