The first time I saw � and heard � a hands-free kit in action was in 1988. (Or was it 1989? Meh, same difference.) At the time, I was pretty impressed with the sound quality. Heck, I was impressed that hands-free conversations were even possible. You have to remember that mobile phones were still an expensive novelty � about $4000 in today�s US dollars. And good grief, they looked like this:It�s almost a shock to see how far we�ve come since 1988. We�ve become conditioned to devices that cost far less, do far more, and fit into much smaller pockets. (Though, admittedly, the size trend for smartphones has shifted into reverse.) Likewise, we�ve become conditioned to hands-free systems whose sound quality would put that 1998 kit to shame. The sound might have been okay at the time, but because of the contrast effect, it wouldn�t pass muster today. Our ears have become too discerning.
Which brings me to a new white paper from Phil Hetherington and Andrew Mohan of the acoustics team at QNX Software Systems. Evaluating hands-free solutions from various suppliers can be a complex endeavor, for the simple fact that hands-free systems have become so sophisticated and complex. To help simplify the decision process, Phil and Andrew have boiled the problem down to 10 key factors:
- Acoustic echo cancellation
- Noise reduction and speech reconstruction
- Multi-channel support
- Automatic gain control
- Equalization
- Wind buffet suppression
- Intelligibility enhancement
- Noise dependent receive gain
- Bandwidth extension
- Wideband support
Ultimately, you must judge a hands-free solution by the quality of the useful sound it delivers. By focusing on these 10 essentials, you can make a much sounder judgment (pun fully intended).
Recently, Electronic Design published a version of this paper on their website. For a longer version, which includes a decision checklist, visit the QNX download center.