How to solve this "xpected primary-expression before ',' token" I'm new in this arduino world, and I'm having some trouble. I am programming something for a school assignment. The program gives an error, and my teacher also doesn't know how to solve it. Maybe someone can help me? 

#include &lt;CapacitiveSensor.h&gt;
#define speaker 

CapacitiveSensor   cs_2_3 = CapacitiveSensor(2,3);        
CapacitiveSensor   cs_2_4 = CapacitiveSensor(2,4);         
CapacitiveSensor   cs_2_5 = CapacitiveSensor(2,5);     
CapacitiveSensor   cs_2_6 = CapacitiveSensor(2,6);     
CapacitiveSensor   cs_2_7 = CapacitiveSensor(2,7);      
CapacitiveSensor   cs_2_8 = CapacitiveSensor(2,8);         
CapacitiveSensor   cs_2_9 = CapacitiveSensor(2,9);  
CapacitiveSensor   cs_2_10 = CapacitiveSensor(2,10);     

int s1;
int s2;
int s3;
int s4;
int s5;
int s6;
int s7;
int s8;


void setup(){ 
  Serial.begin(9600);
}

void loop()                    
{

  s1 =  cs_2_3.capacitiveSensor(3000);
  s2 =  cs_2_4.capacitiveSensor(3000);
  s3 =  cs_2_5.capacitiveSensor(3000);
  s4 =  cs_2_6.capacitiveSensor(3000);
  s5 =  cs_2_7.capacitiveSensor(3000);
  s6 =  cs_2_8.capacitiveSensor(3000);
  s7 =  cs_2_9.capacitiveSensor(3000);
  s8 =  cs_2_10.capacitiveSensor(3000);

  Serial.print("s1: ");
  Serial.println(s1);
  Serial.print("s2: ");
  Serial.println(s2);
  Serial.print("s3: ");
  Serial.println(s3);
  Serial.print("s4: ");
  Serial.println(s4);
  Serial.print("s5: ");
  Serial.println(s5);
  Serial.print("s6: ");
  Serial.println(s6);
  Serial.print("s7: ");
  Serial.println(s7);
  Serial.print("s8: ");
  Serial.println(s8);


  if (s1 &gt; 500){  
    tone(speaker,131);   
   }
  else if (s2 &gt; 500){ 
    tone(speaker,147);   
   }
  else if (s3 &gt; 500){ 
    tone(speaker,165);
   }
  else if (s4 &gt; 500){ 
    tone(speaker,175);
   }
  else if (s5 &gt; 500){ 
    tone(speaker,196);
   }
  else if (s6 &gt; 500){ 
    tone(speaker,220);
   }
  else if (s7 &gt; 500){ 
    tone(speaker,247);
   }
  else if (s8 &gt; 500){ 
    tone(speaker,262);  
   }

  if (s1&lt;=500  &amp;&amp;  s2&lt;=500  &amp;&amp;  s3&lt;=500 &amp;&amp; s4&lt;=500  &amp;&amp;  s5&lt;=500  &amp;&amp;  s6&lt;=500 &amp;&amp;  s7&lt;=500 &amp;&amp;  s8&lt;=500){
    noTone(speaker);
  }
}
This:

#define speaker


defines "speaker" as nothing, an empty string. Then:

tone(speaker,131);


is translated into

tone(,131);


which makes no sense. The compiler expected to find an expression before the comma.