Due to the reduced ability of the Sensorineural Hearing Loss sufferer to differentiate between voice and noise signals, a directional microphone or microphones allow for an improved Signal to Noise Ratio when conversational listening abilities are the primary objective.
A Directional microphone can take several forms:
Simply put, a directional microphone works by sampling the timing differences between sounds arriving from different locations, for example the front and rear ports. The timing difference between these sources is used to attenuate sounds arriving from undesired locations.
It has been noted that whilst documentary evidence exists to demonstrate the improved speech performance with directionality it always presupposed that the listener and sound source were situated in a defined manner (usually face to face). This is because the directionality worked by reducing the intensity of sounds from the rear, relative to sounds from the front. Whilst this ‘face to face’ format may be the predominant way a normal conversation is held, it is certainly not always the case and Adaptive systems are intended to provide some solution to this problem.