A device comprising: a body portion at least partially covering a frame defining an outline of the device; an audio playback circuit comprising an amplifier and signal processing component; a loudspeaker transducer (302, 702) disposed within a portion of the frame and configured to radiate sound directly out of a forward radiation area; and a sealed enclosure (304, 704) coupled to a rear side of the loudspeaker transducer and configured such that rearward radiation from the loudspeaker transducer propagates into and is contained within the sealed enclosure, wherein the sealed enclosure is configured to generate internal resonances that apply a loading to a diaphragm element of the transducer and thereby lower its resonance frequency, wherein the sealed enclosure comprises a transmission line which defines an internal space of the sealed enclosure, wherein the transmission line is defined by an array of segments that effectively increases the length of the transmission line, wherein the array of segments is defined by a set of partial baffles that create a folded duct, wherein the transmission line merges into a cavity of the sealed enclosure (304, 704), and wherein the cavity is defined by available space of the sealed enclosure (304, 704) to fit into a reserved portion of the frame, wherein the transmission line is configured to form a closed pipe acoustically coupled to the transducer through which the rearward radiation propagates to produce standing waves corresponding to the dimensions of the closed pipe, characterised in that the signal processing component is configured to compensate for localized attenuation due to resonance within the transmission line. a body portion at least partially covering a frame defining an outline of the device; an audio playback circuit comprising an amplifier and signal processing component; a loudspeaker transducer (302, 702) disposed within a portion of the frame and configured to radiate sound directly out of a forward radiation area; and a sealed enclosure (304, 704) coupled to a rear side of the loudspeaker transducer and configured such that rearward radiation from the loudspeaker transducer propagates into and is contained within the sealed enclosure, wherein the sealed enclosure is configured to generate internal resonances that apply a loading to a diaphragm element of the transducer and thereby lower its resonance frequency, wherein the sealed enclosure comprises a transmission line which defines an internal space of the sealed enclosure, wherein the transmission line is defined by an array of segments that effectively increases the length of the transmission line, wherein the array of segments is defined by a set of partial baffles that create a folded duct, wherein the transmission line merges into a cavity of the sealed enclosure (304, 704), and wherein the cavity is defined by available space of the sealed enclosure (304, 704) to fit into a reserved portion of the frame, wherein the transmission line is configured to form a closed pipe acoustically coupled to the transducer through which the rearward radiation propagates to produce standing waves corresponding to the dimensions of the closed pipe, characterised in that the signal processing component is configured to compensate for localized attenuation due to resonance within the transmission line.