A Buddhist master—was it Dogen?—said that listening is the gateway to enlightenment; our acoustic sense provides the true path.
Breath can be calmed, and the other senses can be stilled, yet sound still retains its capacity for intrusion.
It does not ask permission.
You can close your eyes, or gaze forward at no place in particular until your vision dissolves. You can sit in zazen posture until the skin of your entire body merges into a single pressure point in the universe. You can overwhelm your nose with incense such that no other scent can penetrate, and your tongue pressed into the roof of your mouth is quick to forget. But the presence-then-not-presence of sound remains unmoved.
Birdsong like a flurry of sparks across your ears; rain against the window like drunken soldiers upon your skull.
And the shimmering void between the notes, and the emptiness that separates each raindrop collision, in that piercing moment of absence—just now, and just now again—a single fleeting instant that traces the echo back to the origin of mind.
