Rigidbody otherRb = collision.rigidbody;
    if (otherRb == null) return;

    Vector3 myVelocity = rb.velocity;
    Vector3 otherVelocity = otherRb.velocity;

    Vector3 relativeVelocity = thisVelocity - otherVelocity;

    float impactForce = relativeVelocity.magnitude;

    float dotProduct = Vector3.Dot(transform.forward, -relativeVelocity.normalized);

 if (dotProduct > 0.5f)
    {
        PlayImpactSoundLerped(impactForce, true);
    }
    else (dotProduct < -0.5f)
    {
        PlayImpactSoundLerped(impactForce, false);
    }


void PlayImpactSound(float impactForce, bool? frontal)
{
    float volume = Mathf.Clamp01(impactForce / 20f);
    float pitch = Mathf.Lerp(0.8f, 1.5f, impactForce / 20f);

    if (frontal == true)
        audioSource.PlayOneShot(frontImpactSound, volume);
    else if (frontal == false)
        audioSource.PlayOneShot(rearImpactSound, volume);
    else
        audioSource.PlayOneShot(sideImpactSound, volume);

    audioSource.pitch = pitch;
}