If you hold down the volume button in standby mode, you will activate/deactivate the Environmental mode. This essentially amplifies the surrounding noise around you when you're not on a call. The idea is that you don't need to take your headset off during a face-to-face conversation. While we think it's a neat idea, we didn't think it was absolutely necessary. Also, when the Environmental mode is on, there was almost too much amplification, resulting in a little bit of background buzz.
The Sound ID 400 is also compatible with Sound ID's Remote Microphone. It acts almost like a hearing aid, especially when you're having a conversation with someone in a very loud environment. Simply pair the two devices, place the remote microphone next to a sound source, and you will hear the sound without much background noise. You could also place the microphone next to the television so you don't have to raise the volume, or you could put it next to a speaker in a lecture if you're a little hard of hearing.
Other features of the Sound ID 400 include the normal answering, ending, and rejecting calls, last-number redial, automatic volume control, a low-battery indicator, and the ability to transfer calls from the headset to the phone and vice versa. It also has multipoint technology, which lets it connect up to two devices at once.
We paired the Sound ID 400 with the Apple iPhone 3G. We were very pleased with the sound quality overall. The Personal Sound modes combined with the noise-canceling Noise Navigation technology results in crystal clear sound on both sides. On our end, we heard our callers loud and clear for the most part. Whenever we encountered particular bad background noise, like in the train station for example, we would simply switch to a different Personal Sound mode to reduce the background noise a bit. This works quite well, though remember that the stronger the Personal Sound, the less natural the voice.
On their end, callers heard us very clearly as well. There was a bit of static and echo at times, and not all environmental sound was blocked, but it was good enough for everyday situations. Call quality was even quite good in wind noise, which we tested by talking in front of a fan. Callers could still hear us, though they said we sounded a bit muffled at times. We also did a test with the Noise Navigation turned off completely, and the sound quality was audibly worse than when it was enabled.
The Sound ID 400 has a rated battery life of 7 hours talk time and eight days.