Methods and apparatus for controlling the output of moving armature transducers

A portable phone alerter having a sound output enhanced magnetic transducer assembly comprising:

• a moving-armature magnetic transducer mounted within an enclosure in the portable phone and adapted to emit a first sound from a first portion and simultaneously to emit a second sound from a second portion, the first sound and second sound both having a phase, the phase of the second sound differing from the phase of the first sound, the transducer having one or more front holes emitting a first sound and one or more rear holes emitting a second sound;
• the enclosure containing the transducer formed by a housing wall and containing a first acoustical cavity and a second acoustical cavity separated by the transducer, the first cavity having a first opening oriented generally perpendicular to the rear holes of the transducer, the second cavity being adapted to direct the second sound from the rear holes to the second opening, the second cavity together with the second opening being further adapted to shift the phase of the second sound to produce a second phase-shifted sound from the second opening, the second phase-shifted sound being in phase with the first sound so as to constructively interfere with the first sound to reinforce the first sound and produce a combined sound having a peak sound output greater than a peak sound output of the first sound or a peak sound output of the second sound, said combined sound for providing an audible alert.

A method of reinforced sound emission from a moving-armature magnetic transducer utilized as an alerter in a portable phone, including the steps of:

• mounting the moving-armature magnetic transducer in an enclosure within the portable phone;
• emitting a first sound from a first side of the magnetic transducer and a second sound from a second side of the magnetic transducer,
• directing the first sound into and out of a first acoustical cavity;
• and
• directing the second sound into and out of a second acoustical cavity, the step of directing the second sound also including phase-shifting the second sound to be in phase with the first sound as it exits the cavity so as to reinforce the first sound and produce a combined sound having a peak sound output greater than a peak sound output of the first sound or a peak sound output of the second sound, said combined sound for providing an audible alert.