How might I trigger an audio oneshot when y position is <0 to play just once?

Unity Engine
,
1

Expectation - When a ball rolls off the floor I want to trigger an audio oneshot to play a “falling” sound.
Problem - With this code the one shot plays many instances of the falling sound. I believe this is because the update continues to see this position as being < 0 and plays multiple instances of the audio file as long as y position is < 0.

using UnityEngine;

public class Ball : MonoBehaviour
{
    public AudioClip ballFall;
    private AudioSource audioSource;

    void Start()
    {
        audioSource = GetComponent<AudioSource>();
    }

    void Update()
    {
        if (transform.position.y < 0)
        {
            audioSource.PlayOneShot(ballFall);
        }
    }
}

Does anyone have suggestions on how might I rewrite the code so the audio will play only once when the threshold is crossed and not again? Thanks!

2

This is working using a bool to tell if the clip was played resulting in a single play of the audio clip:

using UnityEngine;

public class Ball : MonoBehaviour
{
    public AudioClip ballFall;
    private AudioSource audioSource;
    private bool clipPlayed = false;
    private float fallDelay = 0;

    void Start()
    {
        audioSource = GetComponent<AudioSource>();
    }

    void Update()
    {
        if (transform.position.y < fallDelay && !clipPlayed)
        {
            audioSource.PlayOneShot(ballFall);
            clipPlayed = true;
        }
    }
}