

Microphone turns any surface into a multitouch interface - mrsebastian
http://www.extremetech.com/extreme/111847-microphone-turns-any-surface-into-a-multitouch-interface

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bradleyland
The title is grossly misleading. This setup detects "gestures" which is not
the same as the multitouch interfaces we use with our smartphones. Bloggers
threw "multitouch" on the title; not the creator [1].

Nothing in the original article indicates that the setup is able to detect the
location of the touch, only the _type_ of touch. A thump, a tap, a swipe, or a
scratch. The various gestures are mapped to different sounds, creating a
virtual drum set, if you will. The fact that this detection, mapping, and
playback happens so instantaneously is amazing.

I don't mean to take away from the accomplishment. This is an extremely novel
idea, and the product implications are numerous. It's just a shame that the
tech press is distorting the product idea in a way that creates a false
expectation.

<http://www.brunozamborlin.com/mogees/>

~~~
mrsebastian
Hrm, if you watch the video, the tone definitely changes with the location of
the hit -- as in, with the same radius from the microphone, a different note
is produced depending on where a finger strikes the surface. Gestures are also
included, as you say.

With regard to multitouch -- a) some gestures involve more than one point of
contact, and b) there are some bits in the video where it looks like two
fingers are striking a surface at the same time and making two tones/noises.

~~~
bradleyland
Depending upon the type of material, the tone will change when you strike it.
I still think it's a mistake to say that this turns a surface in to a
"multitouch" surface, because of the vast differences between this and what
has commonly been referred to as multitouch.

Again, extremely cool technology, but you couldn't for example, attach a
microphone to a wall and couple this with a projector to control the OS.
That's the inference that gets drawn when you say "multitouch".

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ww520
This is a very creative idea and execution. The next step would be to use two
microphones sitting at a distance to form a triangulation to determine the 2D
location of the touch. Then multitouch can be truly supported.

~~~
edlea
I can't work out if that would be possible or not.

It might be possible to plot the location of a single point in 2D, but how
would you differentiate for multitouch? If you have 2 microphones you might be
able to calculate the distance from each microphone of a touch by timing how
long it takes for the sound of the tap to reach each microphone. However, as
the speed of sound in wood appears to be ~4000 m/s
([http://www.engineeringtoolbox.com/sound-speed-solids-
d_713.h...](http://www.engineeringtoolbox.com/sound-speed-solids-d_713.html))
you'd need to be "listening" at 400kHz to get centimetre accuracy over a 1m
square area.

I can't see how it would be possible to then differentiate between two points
moving at the same time (i.e. a pinch gesture). I'm just assuming regular
microphones are used as the article suggests - I'm not an acoustic engineer so
hopefully I've missed something.

~~~
kabdib
Use a phased array of mics. Classic technology (well, 1960s).

Probably much harder with random mic placement.

~~~
nitrogen
_Probably much harder with random mic placement._

You could run an initial calibration on the system by having the user tap a
large number of points within the touch area and noting the relative phase,
amplitude, and frequency content received by each mic for each location.

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raphman
More or less same technique, presented at UIST in October 2011:

<http://chrisharrison.net/index.php/Research/TapSense>

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NHQ
Contrary to the bloggers report, there is more info and source available:

<http://ftm.ircam.fr/index.php/A_brief_introduction_to_FTM>

<http://imtr.ircam.fr/imtr/Gesture_Follower>

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mhb
Not exactly the same, but worth mentioning:

 _Acoustic tablets have a long technological history, as seen from this 1971
patent..._

<http://en.wikipedia.org/wiki/Acoustic_tablet>

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omegant
Why Is this site so wrong with iphone safary?( stuck page, difficult to scroll
down, unable to go back to HN...). I always promise myself I'll not touch
again this web with a 5' pole( and always forget :/)

