Gregg Stewart has a great article today  at Search Engine Watch on how Voice Search may be the “next big thing” that’s actually already arrived to large degree.
He posts an interesting graph from the Kelsey Group  that estimates some fantastic growth figures for ad-sponsored directory assistance usage over the next few years.
Although I don’t really question any of the points Gregg made, I do think there’s some caveat to voice search: it’s still very prone to error, and there are some significant issues with making usable interfaces with voice/audio systems and introducing advertising into them as well. All of us have very low tolerance of phone tree navigations when we try to call company help lines, and this could easily transfer to low tolerance of audio ads. We have a fairly high tolerance of visual ads which don’t obscure info we’re trying to access on webpages, but using audio interstitials could very easily result in reducing user acceptance of some ad-propelled directory assistance, or if a user has too many experiences where they encounter errors while using them.
So, there’s likely a very thin dividing line across how long one is willing to listen to an audio ad before it becomes unacceptable, and users who encounter problems while using voice search might not ever come back again.
The sort of folx working on these applications are undoubtedly working hard to find that happy medium in monetizing while improving quality, and the ones who get it right will likely win out in this marketplace.
I previously wrote a brief critique on Goog-411 service , if you’re interested in just one example of common issues in voice search.Â People with accents or even mild speech impediments have great difficulty in using voice search systems, and voice search has trouble recognizing all sorts of unusual words/names even from people with clear, unaccented voices.