Intelligent Acoustic Signage

An interesting article on Lamb Wave devices can be found here.

In short Lamb waves are guided elastic waves that propogate in solid plates or layers with free boundaries. The energyis guided along the plate parallel to the boundaries. Now the most imortant factor for Lamb wave proagation is the frequency-thickness product. Only certain fundamental modes are supported depending on the FT product.

So why am I excited about this technology? Well as described in the paper it does open up the realm of "intelligent devices". Let me explain:

By coupling capacitive micromachined vibration transducers which would then couple with lamb waves in structures one could capture the acoustic signage of the external force. This "acoustic image" then could be correlated to templates in a data base for applications ranging from detection of failures (i.e. machine parts) to detection of activity (a keyboad/ touchscreens).



I uploaded this cool video on French Start up which uses the blackboard to remotely command the windows media player on the latop. Guess which song from Queen is rendered ? What the researcher is doing is remarkable. He records the acoustic waves and maps the waves to a key in the database (that's why he has to return to the laptop each time in the beginning). Later on using correlation, of Energy distribution of Fast fourrier transforms with the templates of the recorded audio signals the system is able to detect the correct key.


So the technology is smart, in some fields (big touchscreens) it can even be a killer application .
The new interactive JC Decaux abribus billboards could do even better with such a technology and this could open up a new realm in interactive marketing ( A google AdSense model on billboards ? - if people do not break these things in the first place) giving real time data back to marketing personnel ...

So What do you think ?