A ultra-slim includes bass, alto membranes and acoustical element, where a surrounding embossed pattern is configured on a location adjacent to the rim of the bass membrane to form a dangling edge, and a frame stopping portion formed by a step is disposed on the center thereof. Whereby, a groove formed by a step is disposed on the center of alto membrane, and the acoustical element is formed by stacking a plurality of ceramic material layers together, thereby mounting the acoustical element on the alto membrane, and then lodging the alto membrane in the inner edge of the frame stopping element of the bass membrane to construct a thinned speaker in which sound is guided out through the bass and alto membranes after audio signals are received, capable of the application thereof to thinned products such as iPad, iPhone, cellular phones or notebook computers.