If, like me, you're a headphone addict, you spend most of your time passively listening to podcasts, audiobooks, music, radio and phone calls - your hands free to take care of business.

Whilst you'd probably rather shut the world out completely, you're often obligated to leave 50% of your hearing apparatus unoccupied because it's more courteous or safe.

So which ear do you plug?

I've long suspected that there's something to plugging the left ear. Spoken content seems to stick better, and music feels more stimulating. New research supports my hypothesis.

Neuroscience researchers in Switzerland used fMRI to investigate the impact of various categories of sounds (vocal; non-vocal), emotional valence (positive, neutral, negative) and spacial origin (left, centre, right) on the auditory cortex - the part of the brain that interprets sounds.

They found that participants responded more strongly to positive human sounds like laughter or pleasant vocalisations when it was played through the left ear. 

The left ear is controlled by the brain's right hemisphere, which is typically regarded as the creative and emotional side, as opposed to the left hemisphere, which is more logical and calculating.

I recall reading many years ago that humans can recall around 70% of emotional words whispered into the left ear, compared to 58% in the right. We can also recall melodies more accurately when played through the left ear. I've even heard that mothers instinctively cradle their babies in such a way that they can whisper into their left ear, though I don't know if this is true.

One factor that determines how we perceive sounds is where they come from. People rate looming sounds as more unpleasant, potent, arousing, and intense than receding sounds, especially if they come from behind rather than from in front. This phenomenon has a reasonable evolutionary explanation: A sound approaching from behind could signal a stalking predator. 

Researchers do not yet have a clear understanding as to why our brains favour positive vocalisations coming from the left. Prof Stephanie Clarke thinks that with more research, a better understanding of the mechanisms at play will be formed, from which "we may speculate whether it is linked to hand preference or the asymmetric arrangements of the internal organs."

For now, I'll carry on punishing one eardrum.