I have run both programs without any crashing!

Ok well thanks for doing that. But which do you think is a better approach?

Personally I prefer to use object orientation. There is a small performance hit when using OO but when you start creating larger and more complex sketchs OO is much better and will significantly reduce development time.

No crashes for me either.
But i noticed you call

1.  println(angle);

Thanks,

Yes println() was used for debugging. Anyway it seems to be running fine now and no crash. Maybe it was my computer I don't know, but the OO programme was crashing and the other wasn't. Anyway not an issue now.

I am trying to create a wave that will have it's peak where the sound wave is compressed and a trough where the rarefaction occurs. Exactly the same as is in the first bit of code (using arrays) I posted earlier. But this isn't working, all I can get is a dot to move in a sin wave and progress to the right.

Below is my sketch so far.

1. int numSpots = 300;
2. int amplitude = 30;
3. float frequency = PI/40;
4. //Declare and create the array
5. Spot[] spots = new Spot[numSpots];
6. void setup() {
7.   size(600, 300);
8.   smooth();
9.   noStroke();
10.   for (int i = 0; i < spots.length; i++) {
11.     float x = random(60, width-amplitude);
12.     float m = ((height/2)+30)/2;
13.     float equilib = x;
14.     float xGlide = 10;
15.     float y = random(30, height/2);
16.     //Create each object
17.     spots[i] = new Spot(x, m, equilib, xGlide, y, 3, frequency);
18.   }
19. }
20. void draw() {
21.   frameRate(24);
22.   background (33, 204, 232);
23.   fill(255);
24.   for (int i = 0; i < spots.length; i++) {
25.     if (i==0) {
26.       spots[0].glide();
27.       spots[0].displayInitWave();   
28.       spots[0].speaker();
29.       spots[0].wave();
30.     } else {
31.       spots[i].move(); //Move each object
32.       spots[i].display(); //Display each object
33.     }
34.   }
35. }
36. class Spot {
37.   float x, y, equilib, xGlide, diameter, frequency, angle, m, wy, wx;
38.   //Constructor
39.   Spot(float xpos, float mpos, float equilibpos, float xGlidepos, float ypos, float dia, float fr) {
40.     x = xpos;
41.     m = mpos;
42.     xGlide = xGlidepos;
43.     equilib = equilibpos;
44.     y = ypos;
45.     diameter = dia;
46.     frequency = fr;
47.   }
48.   void move() {//This method moves each of the particles
49.     if (equilib < spots[0].x) { //equilib is the equilibrum position for each dot and spots[0].x is the x variable of the object spots[0]
50.       x = equilib + (sin(angle))*amplitude;
51.       angle += frequency;
52.     }
53.   }
54.   void display() {
55.     if (x > 42) {
56.       ellipse(x, y, diameter, diameter);
57.     }
58.   }
59.   void displayInitWave() { //displays the bar moving across which starts the wave
60.     if (x < width) {
61.       fill(0, 10);
62.       rect(x, 20, 10, height/2 - 10);
63.       fill(255);
64.     }
65.   }
66.   void glide() { //this method moves the original dot which starts the others moving
67.     xGlide += 3.0;
68.     x = xGlide;
69.   }
70.   void wave() {
71.     //for(int j = 0; j <= width -20; j += frequency){
72.     fill(#FF0000);
73.     ellipse(wx, wy, 3, 3);
74.     wy = 210 + (sin(angle + frequency))*amplitude;
75.     angle += frequency;
76.     wx += 1.0;
77.     fill(255);
78.     //}
79.   }
80.   void speaker() {
81.     stroke(1);
82.     fill(#34B3F5);
83.     beginShape();
84.     vertex(40, 20);
85.     vertex(20, m - 20); //m is the mid y-value for the speaker
86.     vertex(10, m - 20);
87.     vertex(10, m + 20);
88.     vertex(20, m + 20);
89.     vertex(40, 2*m - 15);
90.     endShape(CLOSE);
91.     line(20, m - 20, 20, m + 20);
92.     line(10, m - 10, 2, m - 10);
93.     line(10, m + 10, 2, m + 10);
94.     ellipse(2, m - 10, 3, 3);
95.     ellipse(2, m + 10, 3, 3);
96.     noStroke();
97.     fill(255);
98.   }
99. }
100. boolean bStop;
101. void mousePressed()
102. {
103.   bStop = !bStop;
104.   if (bStop)
105.     noLoop();
106.   else
107.     loop();
108. }

Thanks,

Shane