Loudspeaker
A loudspeaker including: a diaphragm having a first radiating surface and a second radiating surface, wherein the first radiating surface and the second radiating surface are located on opposite faces of the diaphragm; a drive unit configured to move the diaphragm based on an electrical signal; a loudspeaker support structure, wherein the diaphragm is suspended from the loudspeaker support structure via one or more loudspeaker suspension elements. The loudspeaker support structure comprises a self-supporting porous shell which encloses a volume configured to receive sound produced by the second radiating surface, wherein at least part of the self-supporting porous shell is provided by at least one self-supporting portion of porous material having a specific airflow resistance in the range 500-10000 Pa·s/m so as to allow sound produced by the second radiating surface to exit the volume enclosed by the shell.
1 . A mid-high frequency loudspeaker including:
a diaphragm having a first radiating surface and a second radiating surface, wherein the first radiating surface and the second radiating surface are located on opposite faces of the diaphragm;
a drive unit configured to move the diaphragm based on an electrical signal;
a loudspeaker support structure, wherein the diaphragm is suspended from the loudspeaker support structure via one or more loudspeaker suspension elements;
wherein the loudspeaker support structure comprises a self-supporting porous shell which encloses a volume configured to receive sound produced by the second radiating surface, wherein at least part of the self-supporting porous shell is provided by at least one self-supporting portion of porous material having a specific airflow resistance in the range 500-5000 Pa·s/m so as to allow sound produced by the second radiating surface to exit the volume enclosed by the shell;
wherein the mid-high frequency loudspeaker has, within a frequency band of 500 Hz-2 kHz, a sound pressure level (SPL) measured on a principal radiating axis that is at least 6 dB higher than the SPL measured at the same listening distance at 180° to the principal radiating axis, for substantially the entire frequency band of 500 Hz-2 kHz.
2 . The mid-high frequency loudspeaker according to claim 1 , wherein the/each self-supporting portion of porous material has a specific airflow resistance in the range 1500-3000 Pa·s/m.
3 . The mid-high frequency loudspeaker according to claim 1 , wherein the self-supporting porous shell is formed entirely of a single self-supporting portion of porous material.
4 . The mid-high frequency loudspeaker according to claim 1 , wherein the/each self-supporting portion of porous material is formed from paper.
5 . The mid-high frequency loudspeaker according to claim 4 , wherein the paper has a density in the range 0.5 g/cm 3 -1 g/cm 3 and a thickness in the range 0.3 mm-2 mm.
6 . The mid-high frequency loudspeaker according to claim 1 , wherein the/each self-supporting portion of porous material is formed from a felted fabric.
7 . The mid-high frequency loudspeaker according to claim 1 , wherein the at least one self-supporting portion of porous material includes a portion of porous material which includes one or more corrugations.
8 . The mid-high frequency loudspeaker according to claim 7 , wherein the one or more corrugations take the form of a plurality of folds or dimples.
9 . The mid-high frequency loudspeaker according to claim 1 , wherein the loudspeaker support structure comprises a frame from which the diaphragm is suspended, and the self-supporting porous shell, wherein the self-supporting porous shell is attached to the frame.
10 . The mid-high frequency loudspeaker according to claim 1 , wherein the diaphragm is suspended from the self-supporting porous shell.
11 . The mid-high frequency loudspeaker according to claim 1 , wherein the volume enclosed by the self-supporting porous shell is 100 cm 3 or less.
12 . A seat assembly that includes:
a headrest;
one or more mid-high frequency loudspeakers, the one or more mid-high frequency loudspeakers being mounted in the headrest of the seat assembly, wherein the/each mid-high frequency loudspeaker includes:
a diaphragm having a first radiating surface and a second radiating surface, wherein the first radiating surface and the second radiating surface are located on opposite faces of the diaphragm;
a drive unit configured to move the diaphragm based on an electrical signal;
a loudspeaker support structure, wherein the diaphragm is suspended from the loudspeaker support structure via one or more loudspeaker suspension elements;
wherein the loudspeaker support structure comprises a self-supporting porous shell which encloses a volume configured to receive sound produced by the second radiating surface, wherein at least part of the self-supporting porous shell is provided by at least one self-supporting portion of porous material having a specific airflow resistance in the range 500-5000 Pa·s/m so as to allow sound produced by the second radiating surface to exit the volume enclosed by the shell;
wherein the/each mid-high frequency loudspeaker has, within a frequency band of 500 Hz-2 kHz, a sound pressure level (SPL) measured on a principal radiating axis that is at least 6 dB higher than the SPL measured at the same listening distance at 180° to the principal radiating axis, for substantially the entire frequency band of 500 Hz-2 kHz.
13 . The seat assembly according to claim 12 , wherein the one or more mid-high frequency loudspeakers include:
a first mid-high frequency loudspeaker, wherein the first mid-high frequency loudspeaker is located within the headrest for use with a first ear of a user located at a listening position that 30 cm or less from the first radiating surface of the diaphragm of the first mid-high frequency loudspeaker;
a second mid-high frequency loudspeaker, wherein the second mid-high frequency loudspeaker is located within the headrest for use with a second ear of a user located at a listening position that is 30 cm or less from the first radiating surface of the diaphragm of the second mid-high frequency loudspeaker;
wherein the seat assembly is configured to position a user who is sat down in a seat portion of the seat assembly such that the first ear of the user is located at the first listening position, and such that the second ear of the user is located at the second listening position.