Changing the audio on key press! Help

I am trying to make it so that always the audio is the “breathing walking” sound and when i press sprint button then the audio is “breathing running”.

I tried using audio.Play and Input.GetButton but it doesn’t work.

Use Input.KeyDown

function Update(){

    if(Input.KeyDown("shift")){
    audio.Play
}
    if(Input.KeyUp("shift")){
    audio.Stop
}
    }

AudioSources audioClips = GetComponents();
bool Sprinting = false;

if (input.getbutton("sprint"){
sprinting = true
}

if(sprinting){
audioClips[0].stop;

//now do a duration check 
//so you know when to play
//the clip again. if so

audioClips[1].play;

}

getcomponents();
gets all audiosources attached as an array;

you can then access each audio source individually to stop and start various ones