Ultrasonic Theremin

UPDATE: i have redone the code in the last hour with the help of some Arduino forum members (mainly "Nick Gammon", thanks!), and now it is way more responsive...New vid up

Friday night i made a thermin using a ultrasonic module. the arduino reads module which says how far away my hand is from it(the module) in centimeters. then according to how far my hand is away from the module, the Arduino plays a coordinating tone. the closer my hand is, the lower the tone the speaker plays and each tone has 5 centimeters. so the first 5cm in front of the sensor is dead space, then 5 to 10cm is the lowest tone, and 10 to 15cm is the a little higher tone and so on up to 70cm

The distortions are actually caused by the code being too efficient, i figured out that i needed to add a delay before the code loops again.

Code:

#define trig 7 //trigger pin on sonar module
#define echo 6 //echo pin
#define spkr 4
#define led 12
int dist; //how far the object is away from the module(cm)
float valueSensor=0;

//tones array which holds the frequency to play.
float pitchTable[] = {
  329.63, //E4
  349.23, //F4
  369.99, //F#4/Gb4
  392.00, // G4
  415.30, // G#4/Ab4
  440.000000, // A
  466.163757, // A#/Bb
  493.83301, // B
  523.251160, // C
  554.365234, // C#/Db
  587.329529, // D
  622.253967, // D#/Eb
  659.255127, // E
  698.456482, // F
  739.988831, // F#/Gb
  783.990845, // G
  830.609375, // G#/Ab
  880.00, //A5
  932.33 //A#5/Bb5
};

#define NUMITEMS(arg) (sizeof (arg) / sizeof (arg [0]))

void setup()
{
  pinMode(echo, INPUT);
  pinMode(trig, OUTPUT);
}

void loop()
{
  //send a trigger signal
  digitalWrite(trig, HIGH);
  delayMicroseconds(10);
  digitalWrite(trig, LOW);
  //receive the trigger signal echo, and calculate cm to the object
  valueSensor= pulseIn(echo, HIGH);
  dist= valueSensor/58;

  // each 5 positions represents a different note
  byte i = dist / 5;

  // play note if in range
  if (i < NUMITEMS (pitchTable))
  {
    tone(spkr,pitchTable[i]);
  }
  else
  {
    tone(spkr,523.251160);
  }
  delay(125);
}

Code for Just Reading Sonar Value:

#define trig 7 //trigger pin on sonar module
#define echo 6 //echo pin
int dist; //how far the object is away from the module(cm)
int valueSensor = 0; //see here, just added this line

void setup()
{
  Serial.begin(9600);
  pinMode(echo, INPUT);
  pinMode(trig, OUTPUT);
}

void loop()
{
  //send a trigger signal
  digitalWrite(trig, HIGH);
  delayMicroseconds(10);
  digitalWrite(trig, LOW);
  //receive the trigger signal echo, and calculate cm to the object
  valueSensor= pulseIn(echo, HIGH);
  dist= valueSensor/58; //converts raw to cm, valueSensor/74/2 = inches
 
  Serial.println(dist);
}

Pics:

LM386 scheme: