The 10 qualities of highly effective hands-free systems

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.