Arduino memsic gyro sensor project w/ processing dataviz

arduinoPart.pde

/*
   Memsic2125
   
   Read the Memsic 2125 two-axis accelerometer.  Converts the
   pulses output by the 2125 into milli-g's (1/1000 of earth's
   gravity) and prints them over the serial connection to the
   computer.
   
   The circuit:
	* X output of accelerometer to digital pin 2
	* Y output of accelerometer to digital pin 3
	* +V of accelerometer to +5V
	* GND of accelerometer to ground
  
   http://www.arduino.cc/en/Tutorial/Memsic2125
   
   created 6 Nov 2008
   by David A. Mellis
   modified 30 Aug 2011
   by Tom Igoe
   
   This example code is in the public domain.

 */

// these constants won't change:
const int xPin = 9;		// X output of the accelerometer
const int yPin = 10;		// Y output of the accelerometer

void setup() {
  // initialize serial communications:
  Serial.begin(115200);
  // initialize the pins connected to the accelerometer
  // as inputs:
  pinMode(xPin, INPUT);
  pinMode(yPin, INPUT);
}

void loop() {
  // variables to read the pulse widths:
  int pulseX, pulseY;
  // variables to contain the resulting accelerations
  int accelerationX, accelerationY;
  
  // read pulse from x- and y-axes:
  pulseX = pulseIn(xPin,HIGH);  
  pulseY = pulseIn(yPin,HIGH);
  
  // convert the pulse width into acceleration
  // accelerationX and accelerationY are in milli-g's: 
  // earth's gravity is 1000 milli-g's, or 1g.
  accelerationX = ((pulseX / 10) - 500) * 8;
  accelerationY = ((pulseY / 10) - 500) * 8;

  // print the acceleration
  Serial.print(accelerationX);
  // print a tab character:
  Serial.print(",");
  Serial.print(accelerationY);
  Serial.print(".");
}

processingPart.pde

import processing.serial.*;
import ddf.minim.*;
import ddf.minim.ugens.*;
Serial myPort; 



// create all of the variables that will need to be accessed in
// more than one methods (setup(), draw(), stop()).
Minim minim;
AudioOutput out;

// the Oscil we use for modulating frequency.
Oscil fm;

void setup()
{
  size(1600, 900);
  myPort = new Serial(this, Serial.list()[2], 115200);
  fill(255);
  minim = new Minim( this );
  out   = minim.getLineOut();
  Oscil wave = new Oscil( 200, 0.8, Waves.TRIANGLE );
  fm   = new Oscil( 10, 2, Waves.SINE );
  fm.offset.setLastValue( 200 );
  fm.patch( wave.frequency );
  wave.patch( out );
}

int x=0, y=0;

String data = "";

void draw()
{
  fill(0, 0, 0, 10);
  noStroke();
  rect(0, 0, width, height);
  pushMatrix();
  translate(width/2, height/2);
  String inBuffer = myPort.readString();   
  if (inBuffer != null) {
    if (inBuffer.indexOf(".") != -1)
    {
      data += inBuffer.substring(0, inBuffer.indexOf("."));
      printData();
    }
    else
    {
      data += inBuffer;
    }
  }
  popMatrix();
}

int oldX,oldY;
color c;

void printData()
{
  c = color(random(255),random(255),random(255));
  x=int(split(data, ',')[0]);
  y=int(split(data, ',')[1]);
  fill(255);
  stroke(c);
  line(oldX,oldY,x,y);
  oldX=x;
  oldY=y;
  ellipse(x, y, 50, 50);
  float modulateAmount = map( y, 0, height, 220, 1 );
  float modulateFrequency = map( x, 0, width, 0.1, 100 );

  fm.frequency.setLastValue( modulateFrequency );
  fm.amplitude.setLastValue( modulateAmount );
  data="";
}

Why is the serial pot on 115200?