1. Field of the Invention
This invention relates generally to audio enhancement and more particularly to systems and methods to enhance audio signals to compensate for phase distortion.
2. Description of the Related Art
When voice or music is reproduced through transducers, such as loudspeakers, which exhibit both spring and mass in their construction, the transducers produce phase shifting of the audio signal throughout the frequency spectrum within which the transducers operate.
Ideally, the cone of a loudspeaker operates as a unit. At a frequency determined by the design of the loudspeaker, the cone propagates a radial wave outward from the voice coil region to the surround region. The loudspeaker delays higher frequency waves with respect to lower frequency waves. In an embodiment, the amount of delay is dependent on the speed of sound permitted by the speaker material. The delay produces phase shifting throughout the frequency spectrum within which the transducers operate.
This has been realized by loudspeaker manufacturers, but little can be done in the manufacturing process to alleviate this problem. Components of speakers, such as cones and diaphragms, have mass. Speaker centering and restoring devices, such as spiders and surrounds, exhibit spring constants. Further, air itself exhibits a spring constant. This combination produces phase shifting throughout the frequency range.
The phase shifting produces significant changes in the waveform, which the transducer is attempting to reproduce. The result is a phase distortion of the audio signal, which is distinctly audible.