PURPOSE: To adjust the axial length of the speaker cabinet without any deterioration in characteristics and improve the easiness of use by axially expanding and contracting the speaker cabinet which is partitioned with two electroacoustic means and two intermediate baffles to constitute air chambers while keeping the airtightness.

CONSTITUTION: The speaker cabinet 16 is divided into the three air chambers with the two intermediate baffles 15 provided with the electroacoustic means 18a and 18b, and received sound radiating means 19 and 20 are provided at parts of the two air chambers. The speaker cabinet part constituting the air chamber 16c surrounded with the two electroacoustic transducing means 18 and two intermediate baffles 15 is separated into two parts, which are airtightly coupled by a movable part 40 which can expand and contract axially. As the capacity of the 3rd air chamber 16c increases, the low-frequency reproduction limit frequency of sound pressure frequency characteristics decreases and the reproduction frequency band expand. The sound pressure frequency characteristics, however, are held nearly flat even the air capacity increases. Consequently, the axial length of the speaker cabinet can be adjusted without deteriorating the sound pressure frequency characteristics.