Systems, devices, and methods for reducing signal noise

A method, comprising:

• receiving one or more source signals measured by one or more source sensors;
• receiving a plurality of reference signals measured by a plurality of reference sensors, the plurality of reference sensors including at least two different types of sensors;
• and
• processing the one or more source signals using one or more adaptive filters that uses as a reference at least one reference signal from the plurality of reference signals to produce a filtered output;
• the filtered output having less than or equal to of the source noise component than the one or more source signals.

A method, comprising:

• receiving one or more source signals measured by one or more source sensor;
• receiving a plurality of reference signals measured by at least one sensor associated with a user and at least one sensor configured to measure movement, the plurality of reference sensors including at least two different types of sensors;
• and
• processing the one or more source signals using a first adaptive filter that uses as a reference at least one reference signal from the at least one sensor associated with the user to produce a first output;
• processing the first output using one or more adaptive filters that uses as a reference at least one reference signal from the at least one sensor configured to measure movement to produce a filtered output;
• the filtered output having less than or equal to of the source noise component than the one or more source signals.