Patent ID: 9736570
Date: 2017-08-15
CPC Classifications: H04R

Claim:
1. An earphone, comprising: a driver comprising a transducer diaphragm; and a nozzle comprising an internal passage having an inlet opening, an outlet opening, and a wall connecting the inlet opening and the outlet opening, the wall comprising an inner surface within the passage, the inner surface extending from the inlet opening to the outlet opening, the outlet opening being smaller area than the inlet opening, the inner surface being longitudinally convexly curved, based on at least one tractrix, between the inlet opening and the outlet opening, the nozzle attached to the driver with the transducer diaphragm facing the inlet opening and the inlet opening positioned nearer to the diaphragm than is the outlet opening, wherein the transducer diaphragm has an effective area of sound propagation, the effective area having an effective radius, the outlet opening having an outlet radius, the effective radius being longer than the outlet radius, wherein the tractrix is defined according to wherein: