Researchers at the Massachusetts Institute of Technology have developed a loudspeaker that can turn any surface into an active sound source. To do this, they used a thin film that can reproduce sound regardless of the surface it’s attached to. This requires some of the energy of a conventional loudspeaker with minimal disturbance.
The relatively simple manufacturing process can be scaled up to make speakers that cover the interior of a car or wallpaper a room. A laser is used to make tiny holes in a polyethylene terephthalate or PET film. An 8-micrometer layer of polyvinylidene fluoride or PVDF, a piezoelectric material that deforms under electrical voltage, is laminated underneath. Then the whole is heated from the bottom and vacuum is applied from the top. This creates small bubbles of PVDF at the locations of the holes in the cover. On the other side, another cover layer is laminated to separate bubbles from the surface on which the speaker is mounted.
For testing, the film was mounted on a wall and a microphone was placed 30 centimeters away. A volume of 66 decibels was achieved at a voltage of 25 volts at 1 kilohertz, at 10 kHz this increased to 86 dB. Where the average speaker uses 1W to produce a comparable sound pressure, only 100 milliwatts of power is required per square meter of speaker area. Queen’s song We Are the Champions in the video below doesn’t sound very good yet, although the developers claim it has “high sound quality.”
Source: Fudzilla
Source: Hardware Info
