I want my Jump sound play one time when jumping

Questions & Answers
1

I Can Play The Jump Sound Multiple Times While My Character Is Still In The Air And I Just Want The Character To Make The Jump Noise Only When He Is On The Ground.
Here Is The Code

public AudioSource jump;

// Update is called once per frame
void Update()
{
    if (Input.GetKeyDown(KeyCode.Space))
        jump.Play();
}

}

2