I had recently purchased version 10 of Dragon and at the same time purchase a wireless Plantronics headset through Dragon. I have been using Dragon for quite some time and I had purchased three or four headsets in the past for use with Dragon. One of the best headsets I purchased was a Sennheiser through Newegg.com. I had done some testing of the different microphones and I had found that the microphones yield S/N ratios of 17 to 20 DB. The microphone input on the computer adds the most amount of noise especially when using the microphone boost. In the past I had used the line input with a specially built preamplifier and audio filter going into the line input of the computer to reduce the amount of noise, this increased the signal-to-noise ratio to about 27 DB. The Plantronics headset inputs through the USB port and yields a signal-to-noise ratio of approximately 22 DB., unfortunately I cannot use the preamp audio filter with this headset, it is extremely light and comfortable and I would definitely recommend it except for the price.
I have been using Dragon for quite some time with Ultrahal and never experienced any problems with Hal hearing what he is saying. I turned off the mic feature in UltraHal so my input would not be inputted automatically and I could have a chance to see what I had dictated. Recognition is very good but while using UltraHal I find we speak of topics off the beaten path which Dragon is not familiar with.