This is really interesting:

The "loudness" of our thoughts -- or how we imagine saying something -- influences how we judge the loudness of real, external sounds, a team of researchers from NYU Shanghai and NYU has found.

No-one but you knows what it's like to be inside your head and be subject to the constant barrage of hopes, fears, dreams — and thoughts:
"Our 'thoughts' are silent to others -- but not to ourselves, in our own heads -- so the loudness in our thoughts influences the loudness of what we hear," says Poeppel, a professor of psychology and neural science.

Using an imagery-perception repetition paradigm, the team found that auditory imagery will decrease the sensitivity of actual loudness perception, with support from both behavioural loudness ratings and human electrophysiological (EEG and MEG) results.

“That is, after imagined speaking in your mind, the actual sounds you hear will become softer – the louder the volume during imagery, the softer perception will be,” explains Tian, assistant professor of neural and cognitive sciences at NYU Shanghai. “This is because imagery and perception activate the same auditory brain areas. The preceding imagery already activates the auditory areas once, and when the same brain regions are needed for perception, they are ‘tired’ and will respond less."

This is why meditation, both in terms of trying to still your mind, and meditating on positive things you read, is such a useful activity.

As anyone who’s studied philosophy, psychology, and/or neuroscience knows, we don’t experience the world directly, but find ways to interpret the “bloomin' buzzin' confusion”:

According to Tian, the study demonstrates that perception is a result of interaction between top-down (e.g. our cognition) and bottom-up (e.g. sensory processing of external stimulation) processes. This is because human beings not only receive and analyze upcoming external signals passively, but also interpret and manipulate them actively to form perception.
Source: Science Daily