unity3d – How do I get the joystick axis as a float in Unity 3D

I am trying to make audio play at the same speed as the player movement. Right now I have the audio playing as a float and the character moving with Unity’s character controller. How do I get the controller x and y axis as a float?

//Moving/Jumping
public CharacterController controller;

public float originalSpeed = 12;
public float speed = 12;
public float sprintSpeed = 20;
public float crouchSpeed = 5;
public float gravity = -50;
public float jumpHeight = 3f;

Vector3 velocity;

public float defaultSprintTime;
public float sprintTime;

private float x;
private float y;

In the update function:

        //Getting the movement input
    float x = Input.GetAxis("Horizontal");
    float z = Input.GetAxis("Vertical");

    //Moving the player
    Vector3 move = transform.right * x + transform.forward * z;

    controller.Move(move * speed * Time.deltaTime);

In the audio coroutine:

if (playingStoneSound == false)
    {
        int randomSound = Random.Range(0, FootstepStone.Length); //Makes an int which randomly generates what audio source in the array should be played
        FootstepStone[randomSound].Play(); //Plays audio from the array using the randomly generated int
        playingStoneSound = true; //Making the bool true so you cannot play the sound again until it is done

        if (stillCrouching == true) //If you are crouching play the sound slower
        {
            yield return new WaitForSeconds(0.85f); //Waits before playing the sound again
            playingStoneSound = false; //Making the bool false so you can play the sound again
        }
        else //If you are not crouching
        {
            yield return new WaitForSeconds(speed); //Waits before playing the sound again -- This is where I want my audio to change depending on the joystick speed
            playingStoneSound = false; //Making the bool false so you can play the sound again
        }
    }