Singing in the shower is not uncommon. Moreover, this is done by people who are often ashamed to sing in public or who believe, sometimes not without reason, that they have neither voice nor hearing. They sing without realizing why they are doing it.
A surge of cheerfulness
In fact, it is natural for a person to sing when he feels joyful and happy. Taking a shower, he gets a charge of vivacity: hot water, massage while rubbing the body with a washcloth make the blood circulate more intensively, the heart beats faster. Contrasting water jets stimulate the skin. The pores open, the person breathes not only with full chest, but literally with the whole body!
And this happens precisely in the process of taking a shower. Few people would think of singing while immersed in a bath - this position contributes to a rather relaxed and contemplative mood. Being in an upright position, actively moving, a person feels much more energetic, and he has a desire to express this state through singing.
Music of falling streams
The sound of water, the sound of many drops breaking on the echoing surface of the bathtub create a certain "musical accompaniment". The human ear is able to catch a certain rhythm and a kind of harmony in this seeming cacophony. Perceiving the surrounding vibrations, he can feel the desire to join them, join this chorus, add his voice to it. And the person sings, feeling himself in harmony with the environment!
The illusion of loneliness and isolation
Another reason why a person feels the desire to sing in his soul is the illusion of loneliness and isolation from the outside world. Yes, he intellectually understands that he is in an apartment where, perhaps at this moment, his loved ones are present, and neighbors live behind the wall. But the closed small space of the bath or shower stall creates a feeling of isolation from all these people, from the outside world. There are only wet walls, water falling from above, the pleasant scent of shampoo or shower gel, the fresh smell of toothpaste, and he is naked and completely alone.
There are people who cannot stand silence and loneliness. As a rule, these are pronounced extroverts. They strive to fill the space around them, if not with people, then at least with sounds: they turn on the TV or music "for the background." They were the ones who probably came up with shower radios or music playback devices that are not afraid of the humidity of the bathroom. If such a person is deprived of the technical ability to neutralize the "emptiness and silence" around him, he begins to sing.
There are those who feel uncomfortable in a confined space. Perhaps such people try to cheer themselves up by singing, which, in general, is quite natural.
They also sing too shy people who cannot find a way to express themselves "publicly". The feeling of security in a closed bathroom gives them courage and self-confidence, and they finally dare to express themselves in full voice!