[UKönig]

"3. actively with ASDIC - they send out a sound pulse or ping which reflects off the hull of the submarine and tells the destroyer where and how deep you are."

Actually GR, The one thing ASDIC cannot tell the operator is how deep you are. It can reveal direction, but not depth. They too must use their intuition or instincts to bomb the right place. If you have newbie HKs, you'll have a better chance of avoiding, but if you are on the hook by experienced crews, you will have to push your boat to the limits of its depth design.
By then, it won't be the bombs that kill you, it will be pressure hull failure.

In the novel "das boot", it is described as...(paraphrased)

...The enemy has us trapped in the tendrils of his direction finder. Right now, they're turning the handwheels, searching through the 3 dimensions with pulsing beams.
The ASDIC, I remind myself, is only effective up to a speed of 13 knots. Any faster and the destroyer can no longer maintain contact. At higher speed, the ASDIC suffers interference from the ship's own noises, including its propellers, which is an advantage for us, because it allows a last moment chance to change course a little. But the enemy captain knows that we won't stand still and wait for an attack, only, which way we move is the one thing his directional boys can't tell him. Here, he has to use his own instinct.
One more break for us is that our enemy and his clever machine cannot reveal how deep we are. In this, nature is on our side. Water is not simply water. Right down to our present depth it forms layers, like sedimentary rock. The salt content and physical conditions of these layers changes constantly. And they scatter the ASDIC. All we have to do is move suddenly from a layer of warm water to a layer of cold, and the beam becomes inaccurate. Even a layer of dense plankton can influence it. And the enemy above with their apparatus cannot correct their course plotting for us, because they don't know where these dammed layers are.

But once they've found you, and are pinging your boat, being quiet is no longer part of it. Might as well make all the racket you can and go deep as fast as you can. Go silent after a series of blasts and that will help confuse them as they search the depths, actively and passively to find you again.