Public Declare Function sndPlaySound Lib "winmm.dll" Alias "sndPlaySoundA" (ByVal lpszSoundName As String, ByVal uFlags As Long) As Long
Const SND_ASYNC = &H1 'modo asíncrono. La función retorna una vez iniciada la música (sonido en background).
Const SND_LOOP = &H8 'La música seguirá sonando repetidamente hasta
'que la función sndPlaySound sea llamada de nuevo con un valor nulo para NombreWav (NULL).

Private Sub Command1_Click()
    Unload Me
    'Para detener lo que se esté tocando
    Call sndPlaySound(ByVal "", 0)
End Sub

Private Sub Form_Load()
    'Para tocar un Wav de forma indefinida:
    Call sndPlaySound(ByVal "\siren.wav", SND_ASYNC + SND_LOOP)
End Sub

Compile error:

Constants, fixed-length strings, arrays, user-defined types and Declare statementa not allowed as Public members of object modules