Hear Steps Help

[Star]

I was reading this thread here

http://www.rmxp.org/forums/index.php?topic=12980

And I thought it would be pretty cool to script different sounds for different terrain tags.  But so far I haven't gotten any luck of how to do this right.

Here's the edit I've made so far.  But no matter what I do.  It either makes the same sound play for every terrain, or it doesn't play a sound at all

Spoiler

#==============================================================================
# ** Hear_Steps
#------------------------------------------------------------------------------
#  by arevulopapo
#  9.11.2006
#==============================================================================

class Game_Character
  #--------------------------------------------------------------------------
  attr_accessor :hear_steps
  attr_accessor :step_sound
  attr_accessor :water_sound
  #--------------------------------------------------------------------------
  alias hs_init initialize
  def initialize
    hs_init
    @hear_steps = false
    @step_sound = "Audio/SE/Walk"
    @water_sound = "Audio/SE/splash"
  end
  alias hs_update update
  def update
    if self.moving? and self.hear_steps == true and (Graphics.frame_count + 2 * self.id) % (18 - @move_speed) == 0
      if self.screen_x > 0 and self.screen_x < 640 and self.screen_y > 0 and self.screen_y < 480
        if terrain_tag = 1
          volume = 100 - 5 * Math.sqrt((self.x - $game_player.x)**2 + (self.y - $game_player.y)**2)
          Audio.se_play(@step_sound, volume, 100)
        end
        if terrain_tag = 2
          volume = 100 - 5 * Math.sqrt((self.x - $game_player.x)**2 + (self.y - $game_player.y)**2)
          Audio.se_play(@water_sound, volume, 100)
          end
      end
    end
    hs_update
  end
end

Any pointers?