Not long ago researchers at MIT have shown a loudspeaker that is thinner than a sheet of paper. It has a thickness of a few microns and the novelty is the way it has to generate the sound.
Until now, the speakers we know have a membrane that vibrates and produces sound waves. In this new case it is a piezoelectric material where there are small domes that vibrate individually when the electric current passes through them, and these domes measure one sixth of the thickness of a human hair.
Being so small, they are very sensitive to the passage of current and therefore sounds are generated with much lower consumption than current speakers. On the order of a tenth.
Once the prototype is made, it remains to be seen the quality of the sound in all frequencies (especially those that are audible) to find practical applications in different markets.
In the following video you can see a small demonstration: https://dai.ly/x8ae1yq
Size and consumption are two very important advantages, but the quality of the sound it provides is essential for some types of market.
Being so fine, it can be adapted to any type of surface, both straight and curved, thus increasing the number of its possible applications.
It seems ideal for use in closed places such as cars, planes, etc... in which it is important to reduce environmental noise, since this is achieved by applying a sound signal in phase opposition to that of ambient noise, and here quality is not the most important.
It could also be useful in some devices that have very little power to drive a speaker. But I don't see it competing with a home audio system with good bass quality.
At the moment it is a very interesting development, and it remains to be seen how far it can go in its practical applications. But again, it is interesting.
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