Earphone device, sound tube forming a part of earphone device and sound generating apparatus

A sound generating apparatus for supplying sound to a human being, comprising:

• a source of sound signal for producing a sound signal;
• a source of voltage for generating voltage;
• and
• an earphone device connected to said source of sound signal and said source of voltage for sending out sound into at least one external ear of said human being, and including
• a signal-to-sound converter converting said sound signal to internal sound,
• an ear coupler engaged with said at least one external ear of said human being and formed with a first sound propagation path open at one end thereof to said at least one external ear so that external sound and said internal sound are sent out into said external ear of said human being and
• a sound tube connected between said signal-to-sound converter and said ear coupler and formed with a second sound propagation path connected at one end thereof to the other end of said first sound propagation path and at the other end thereof to said signal-to-sound converter so that said internal sound is propagated from said signal-to-sound converter to said first sound propagation path, said sound tube being further formed with an external sound entrance open at one end thereof to environment and at the other end thereof to said second sound propagation path,
• an active valve unit supported by said sound tube and responsive to voltage so as to be deformed for closing said external sound entrance therewith and permitting said environment to be conducted to said second sound propagation path through said external sound entrance, and
• an electric coupling connected between said source of voltage and said active valve unit for supplying said voltage to said active valve unit.