return {
  dirt = {
       {
         filename = "__base__/sound/walking/dirt-02.ogg",
         volume = 0.8
       },
       {
         filename = "__base__/sound/walking/dirt-03.ogg",
         volume = 0.8
       },
       {
         filename = "__base__/sound/walking/dirt-04.ogg",
         volume = 0.8
       }
  },
  grass = {
        {
          filename = "__base__/sound/walking/grass-01.ogg",
          volume = 0.8
        },
        {
          filename = "__base__/sound/walking/grass-02.ogg",
          volume = 0.8
        },
        {
          filename = "__base__/sound/walking/grass-03.ogg",
          volume = 0.8
        },
        {
          filename = "__base__/sound/walking/grass-04.ogg",
          volume = 0.8
        }
  },
  ice = {
        {
          filename = "__base__/sound/walking/concrete-01.ogg",
          volume = 1.2
        },
        {
          filename = "__base__/sound/walking/concrete-02.ogg",
          volume = 1.2
        },
        {
          filename = "__base__/sound/walking/concrete-03.ogg",
          volume = 1.2
        },
        {
          filename = "__base__/sound/walking/concrete-04.ogg",
          volume = 1.2
        }
  },
  sand = {
        {
          filename = "__base__/sound/walking/sand-01.ogg",
          volume = 0.8
        },
        {
          filename = "__base__/sound/walking/sand-02.ogg",
          volume = 0.8
        },
        {
          filename = "__base__/sound/walking/sand-03.ogg",
          volume = 0.8
        },
        {
          filename = "__base__/sound/walking/sand-04.ogg",
          volume = 0.8
        }
  },
  sand = {
        {
          filename = "__base__/sound/walking/sand-01.ogg",
          volume = 0.8
        },
        {
          filename = "__base__/sound/walking/sand-02.ogg",
          volume = 0.8
        },
        {
          filename = "__base__/sound/walking/sand-03.ogg",
          volume = 0.8
        },
        {
          filename = "__base__/sound/walking/sand-04.ogg",
          volume = 0.8
        }
  },
  snow = {
    { filename = "__alien-biomes__/sound/walking/snow-01.ogg", volume = 0.75 },
    { filename = "__alien-biomes__/sound/walking/snow-02.ogg", volume = 0.75 },
    { filename = "__alien-biomes__/sound/walking/snow-03.ogg", volume = 0.75 },
    { filename = "__alien-biomes__/sound/walking/snow-04.ogg", volume = 0.75 },
    { filename = "__alien-biomes__/sound/walking/snow-05.ogg", volume = 0.75 },
    { filename = "__alien-biomes__/sound/walking/snow-06.ogg", volume = 0.75 },
    { filename = "__alien-biomes__/sound/walking/snow-07.ogg", volume = 0.75 },
    { filename = "__alien-biomes__/sound/walking/snow-08.ogg", volume = 0.75 },
    { filename = "__alien-biomes__/sound/walking/snow-09.ogg", volume = 0.75 },
    { filename = "__alien-biomes__/sound/walking/snow-10.ogg", volume = 0.75 },
  },
  water = {
    { filename = "__alien-biomes__/sound/walking/water-01.ogg", volume = 0.9 },
    { filename = "__alien-biomes__/sound/walking/water-02.ogg", volume = 0.9 },
    { filename = "__alien-biomes__/sound/walking/water-03.ogg", volume = 0.9 },
    { filename = "__alien-biomes__/sound/walking/water-04.ogg", volume = 0.9 },
    { filename = "__alien-biomes__/sound/walking/water-05.ogg", volume = 0.9 },
    { filename = "__alien-biomes__/sound/walking/water-06.ogg", volume = 0.9 },
    { filename = "__alien-biomes__/sound/walking/water-07.ogg", volume = 0.9 },
    { filename = "__alien-biomes__/sound/walking/water-08.ogg", volume = 0.9 },
    { filename = "__alien-biomes__/sound/walking/water-09.ogg", volume = 0.9 },
    { filename = "__alien-biomes__/sound/walking/water-10.ogg", volume = 0.9 },
    { filename = "__alien-biomes__/sound/walking/water-11.ogg", volume = 0.9 },
    { filename = "__alien-biomes__/sound/walking/water-12.ogg", volume = 0.9 },
  }
}
