Question
Can you please discuss the advantages and disadvantages of the multiple polar plots available in digital products? Specifically, what are the ideal situations for each polar pattern?
Answer
The dual microphone feature has been enhanced by the introduction of a series of digitally controlled inter-microphone delays, allowing the user or the fitter to select either a cardiod directional, a hyper-cardiod directional, or a bi-directional polar pattern.
The cardiod directional places the polar plot null directly behind the patient (180 degrees) and would be most useful when the offensive background noise originates directly from behind. The hypercardioid pattern introduces two nulls, one at 120 and one at 240 degrees, and is most useful in diffuse background noise situations. The bi-directional pattern introduces two nulls at 90 and 270 degrees, reducing noise sources from either side, but providing amplification to sounds from the front and behind. This pattern has classically been described as appropriate for taxi-cab drivers, but can also be useful for wearers working in cubicles where they might be spoken to or addressed from behind.
BIO:
David Smriga, M.A., holds a bachelor's degree in communication disorders and a master's degree in Audiology, both from Northern Illinois University, DeKalb, Illinois. Smriga has authored over 45 publications and has conducted more than 350 seminars in both the United States and Canada on audiologic and other industry issues.