Like on the SM100, the Sound ID 300 comes with three Personalized Sound modes to increase speech intelligibility depending on your preference. The three modes are Normal Listening Enhancement, Moderate, and Strong, and you can toggle through these with the aforementioned volume key. If you prefer a more natural sounding voice with not as much difference between the voice and the background, you would opt for Normal mode. If you prefer to really set the speech apart from the surrounding noise, you would opt for the Moderate or Strong Listening Enhancement modes. Do note that you would be sacrificing the "natural" quality of the speech the stronger the mode, resulting in a more machine-like voice.
We paired the Sound ID 300 with the Apple iPhone 3G. Because of the Noise Navigation technology plus the dual microphone noise cancellation, callers could hear us very clearly, even in a busy cafeteria. Call quality didn't fare so well with wind noise, though, with some static and echo at times. Still, we could hear our callers clearly enough, especially with the help of the Personalized Sound modes.
To really tell the significance of the Noise Navigation, we turned it off to compare the call quality with and without it. Indeed, having the noise cancellation on makes a huge difference--there was a lot more background noise without it. The automatic volume adjustment also did a great job in adjusting the incoming volume levels, depending on whether we were in a quiet environment or in a noisier one.
Other features of the Sound ID 300 include answering, ending, and rejecting calls, call-waiting support, voice-dial support, call mute, and a battery life indicator. The Sound ID 300 has a rated talk time of 6 hours and a standby time of 9 days.