These works featured minimal melodies and often had subtle, weird and unnatural noises within the song structures.

"Even a subtle noise that doesn't actually wake you up is disruptive enough to affect the sleep quality," Dr. Stepanski said.

It was only then that we heard the soft, subtle noises from the trunk at the back.

All this told Jeffrey that Challenger's hydrophone arrays were working hard to pull in even the subtlest noises from outside.

She almost missed the noise, so subtle was it, like the faintest scratching sound.

Based on the video you're about to see, we've made subtle noises to RTG.

And there was smirking going on; a smirk makes a subtle noise if you're listening for it.

Unable to identify the subtle noise, many listened instinctively for some change in the flow of the nearby Lower Rhine.

And The Pride was proceeding with power-down, a series of subtle noises that her ear knew in every nuance.

The air transmitted a whole choir of subtle humming, whining noises to my shielded ears, and smelled a little like a hospital's, except cleaner.