Confusing Sounds

Hey guys I just started putting sounds into my project and I came along a problem. I have tried to find a solution on the forums and through google but there is little that is helping. I basically want to change an audioclip being played based on the number of a variable. I find that the audio clip is successfully changing, but I believe because it is updating over and over that the audioclip does not have a chance to complete before it instantly starts again.

Here is my script

var thrustidle : AudioClip;
var thrustone : AudioClip;
var thrusttwo : AudioClip;
var thrustthree : AudioClip;

var thrusters: AudioClip;

function Update () {

if (BasicFlightControl.throttle <= 0) {

audio.clip = thrustidle;
     
audio.Play();
}

if (BasicFlightControl.throttle >= 1  BasicFlightControl.throttle <=3) {

audio.clip = thrustone;
     
audio.Play();
}



if (BasicFlightControl.throttle >= 4  BasicFlightControl.throttle <=6) {

audio.clip = thrusttwo;
audio.Play();
     
}

if (BasicFlightControl.throttle >= 7  BasicFlightControl.throttle <=10) {

audio.clip = thrustthree;
  audio.Play();   

}



}

How would I go about modifying it so that it does not keep trying to play all the time?

You need to check if the audio is already playing.

if (!audio.isPlaying) audio.Play();