Providing speakers in a vehicle seat

A seat comprising:

• a seat back having a first vertically-oriented cavity open at the top of the seat back;
• a first speaker enclosure comprising:
• a speaker having a sound-radiating element with a first side and a second side, and
• an at least partially enclosed volume of space larger than a volume of space occupied by the speaker and acoustically coupled to the second side of the sound-radiating element of the speaker,
• the enclosure sized to fit within the first cavity;
• a motor coupled to the first speaker enclosure and operable to move the first speaker enclosure between a first position in which the first speaker enclosure is fully contained within the first cavity and a second position in which the first speaker enclosure protrudes from the top of the seat back such that the first side of the sound-radiating element is coupled to free space at the top of the seat back;
• and
• a headrest, wherein:
• the headrest comprises a vertically-oriented shaft that protrudes into the seat back and supports the headrest in at least two vertical positions;
• and
• the first speaker enclosure further comprises a protrusion extending from the enclosure and aligned with the shaft of the headrest, such that the protrusion limits the upper vertical extent of the second position of the first speaker enclosure according to the position of the headrest.