A dual mode transducer (600) includes an electromagnetic driver (604), an armature including upper and lower substantially parallel planar suspension members (610) coupled to the driver (604), and a magnetic motional mass (616) suspended between the suspension members (610). The suspension members (610)...http://www.google.de/patents/US5524061?utm_source=gb-gplus-sharePatent US5524061 - Dual mode transducer for a portable receiver
