1D multiple peak detection? - actionscript-3

Question

I am currently trying to implement basic speech recognition in AS3. I need this to be completely client side, as such I can't access powerful server-side speech recognition tools. The idea I had was to detect syllables in a word, and use that to determine the word spoken. I am aware that this will grealty limit the capacities for recognition, but I only need to recognize a few key words and I can make sure they all have a different number of syllables.
I am currently able to generate a 1D array of voice level for a spoken word, and I can clearly see, if I somehow draw it, that there are distinct peaks for the syllables in most of the cases. However, I am completely stuck as to how I would find out those peaks. I only really need the count, but I suppose that comes with finding them. At first I thought of grabbing a few maximum values and comparing them with the average of values but I had forgot about that peak that is bigger than the others and as such, all my "peaks" were located on one actual peak.
I stumbled onto some Matlab code that looks almost too short to be true, but I can't very that as I am unable to convert it to any language I know. I tried AS3 and C#. So I am wondering if you guys could start me on the right path or had any pseudo-code for peak detection?

Answer 1

The matlab code is pretty straightforward. I'll try to translate it to something more pseudocodeish.
It should be easy to translate to ActionScript/C#, you should try this and post follow-up questions with your code if you get stuck, this way you'll have the best learning effect.
Param: delta (defines kind of a tolerance and depends on your data, try out different values)
min = Inf (or some very high value)
max = -Inf (or some very low value)
lookformax = 1
for every datapoint d [0..maxdata] in array arr do
this = arr[d]
if this > max
max = this
maxpos = d
endif
if this < min
min = this
minpos = d
endif
if lookformax == 1
if this < max-delta
there's a maximum at position maxpos
min = this
minpos = d
lookformax = 0
endif
else
if this > min+delta
there's a minimum at position minpos
max = this
maxpos = d
lookformax = 1
endif
endif

Answer 2

Finding peaks and valleys of a curve is all about looking at the slope of the line. At such a location the slope is 0. As i am guessing a voice curve is very irregular, it must first be smoothed, until only significant peaks exist.
So as i see it the curve should be taken as a set of points. Groups of points should be averaged to produce a simple smooth curve. Then the difference of each point should be compared, and points not very different from each other found and those areas identified as a peak, valleys or plateau.

Answer 3

If anyone wants the final code in AS3, here it is:
function detectPeaks(values:Array, tolerance:int):void
{
var min:int = int.MIN_VALUE;
var max:int = int.MAX_VALUE;
var lookformax:int = 1;
var maxpos:int = 0;
var minpos:int = 0;
for(var i:int = 0; i < values.length; i++)
{
var v:int = values[i];
if (v > max)
{
max = v;
maxpos = i;
}
if (v < min)
{
min = v;
minpos = i;
}
if (lookformax == 1)
{
if (v < max - tolerance)
{
canvas.graphics.beginFill(0x00FF00);
canvas.graphics.drawCircle(maxpos % stage.stageWidth, (1 - (values[maxpos] / 100)) * stage.stageHeight, 5);
canvas.graphics.endFill();
min = v;
minpos = i;
lookformax = 0;
}
}
else
{
if (v > min + tolerance)
{
canvas.graphics.beginFill(0xFF0000);
canvas.graphics.drawCircle(minpos % stage.stageWidth, (1 - (values[minpos] / 100)) * stage.stageHeight, 5);
canvas.graphics.endFill();
max = v;
maxpos = i;
lookformax = 1;
}
}
}
}