Metal sounds:

default_dig_metal.ogg - yadronoff - CC-BY-3.0

- https://www.freesound.org/people/yadronoff/sounds/320397/

default_dug_metal.*.ogg - Iwan Gabovitch - qubodup - CC0

- http://opengameart.org/users/qubodup

default_metal_footstep.*.ogg - Ottomaani138 - CC0

- https://www.freesound.org/people/Ottomaani138/sounds/232692/

default_place_node_metal.*.ogg - Ogrebane - CC0

- http://opengameart.org/content/wood-and-metal-sound-effects-volume-2

function default.node_sound_metal_defaults(table)

table = table or {}

table.footstep = table.footstep or

{name = "default_metal_footstep", gain = 0.5}

table.dig = table.dig or

{name = "default_dig_metal", gain = 0.5}

table.dug = table.dug or

{name = "default_dug_metal", gain = 0.5}

table.place = table.place or

{name = "default_place_node_metal", gain = 0.5}

default.node_sound_defaults(table)

return table