An in-ear earpiece comprising: an eartip comprising: a round body configured to rest in the concha of an ear of a user including an earpiece mating surface for coupling to a housing of an electroacoustic transducer of the earpiece such that a conical structure and the round body are positioned between the user's ear and the housing when the eartip is inserted into the ear of the user; a positioning and retaining structure comprising the round body to engage features of the lateral surface of the ear of the user to position the earpiece and to hold the earpiece in place; a conical structure configured to engage the entrance of the ear canal and formed of material that conforms to the entrance to the ear canal to seal the ear canal, wherein the round body is joined to the conical structure by a passageway through the interior of the conical structure, ending at a smaller end of the conical structure, a volume of air between the passageway and a wall of the conical structure providing room for the conical structure to deform when inserted into the ear of the user, wherein the conical structure is not responsible for retention of the in-ear earpiece. an eartip comprising: a round body configured to rest in the concha of an ear of a user including an earpiece mating surface for coupling to a housing of an electroacoustic transducer of the earpiece such that a conical structure and the round body are positioned between the user's ear and the housing when the eartip is inserted into the ear of the user; a positioning and retaining structure comprising the round body to engage features of the lateral surface of the ear of the user to position the earpiece and to hold the earpiece in place; a conical structure configured to engage the entrance of the ear canal and formed of material that conforms to the entrance to the ear canal to seal the ear canal, wherein the round body is joined to the conical structure by a passageway through the interior of the conical structure, ending at a smaller end of the conical structure, a volume of air between the passageway and a wall of the conical structure providing room for the conical structure to deform when inserted into the ear of the user, wherein the conical structure is not responsible for retention of the in-ear earpiece. a round body configured to rest in the concha of an ear of a user including an earpiece mating surface for coupling to a housing of an electroacoustic transducer of the earpiece such that a conical structure and the round body are positioned between the user's ear and the housing when the eartip is inserted into the ear of the user; a positioning and retaining structure comprising the round body to engage features of the lateral surface of the ear of the user to position the earpiece and to hold the earpiece in place; a conical structure configured to engage the entrance of the ear canal and formed of material that conforms to the entrance to the ear canal to seal the ear canal, wherein the round body is joined to the conical structure by a passageway through the interior of the conical structure, ending at a smaller end of the conical structure, a volume of air between the passageway and a wall of the conical structure providing room for the conical structure to deform when inserted into the ear of the user, wherein the conical structure is not responsible for retention of the in-ear earpiece.