diff --git a/dev/devSandbox.m b/dev/devSandbox.m
index 29165b3..637830a 100644
--- a/dev/devSandbox.m
+++ b/dev/devSandbox.m
@@ -23,22 +23,62 @@
     % Init the structure that will contain PTB setup
     cfg = struct;
 
+    %% Visual
+
+    % set to false if no visual stimulation
+    cfg.screen.do = true;
+
     % Set the PTB window background manually
-    cfg.color.background = [127 127 27];
+    cfg.color.background = [127 127 127];
+
+    % Set monitor parameters if you care about visual angle
+    cfg.visualAngle.do = true;
+    cfg.screen.monitorWidth = 21.5; % cm
+    cfg.screen.monitorDistance = 30; % cm
 
     % Init PTB, see the Sub-Functions below
     cfg = devSandbox_initPTB(cfg);
 
+    % OUTPUT:
+    %
+    %  cfg.screen.idx % Screen number where to draw, external screen if avaliable
+    %  cfg.screen.win % The onscreen window whose content should be shown at flip time
+    %  cfg.screen.winRect % The onscreen window size in pixels coordinates
+    %  cfg.screen.winWidth
+    %  cfg.screen.winHeight
+    %  cfg.screen.center % Center of the screen window
+    %  cfg.screen.ifi % Frame duration
+    %  cfg.screen.monitorRefresh % Monitor refresh rate
+
+    % Compute pixels per degrees
+    cfg = devSandbox_computePpd(cfg);
+
+    % OUTPUT:
+    %
+    % cfg.screen.ppd % The number of pixels per degree given the distance to screen
+
+    %% Auditory
+    % Set AUDIO
+
+    % set to false if no auditory stimulation
+    cfg.audio.do = true;
+
+    % Set audio freq. and nb. of channels of your audio file input
+    cfg.audio.fs = 44100;
+    cfg.audio.channels = 2;
+
+    % Init Audio, see the Sub-Functions below
+    cfg = devSandbox_initAudio(cfg);
+
+    % OUTPUT:
+    %
+    % cfg.audio.pahandle
+
     %%
     % -------------------------------------------------------------------------
     % -------------------------- SET YOUR VARS HERE ---------------------------
     % -------------------------------------------------------------------------
 
-    % Define black and white
-    white = WhiteIndex(cfg.screen.idx);
-    grey = white / 2;
-    inc = white - grey;
-
     % Grating size in pixels
     gratingSizePix = 600;
 
@@ -66,6 +106,12 @@
         % -------------------------------------------------------------------------
         % ------------------------------ PLAYGROUND -------------------------------
         % -------------------------------------------------------------------------
+
+        % Define black and white
+        white = WhiteIndex(cfg.screen.idx);
+        grey = white / 2;
+        inc = white - grey;
+
         % Define Half-Size of the grating image.
         textureSize = gratingSizePix / 2;
 
@@ -167,29 +213,65 @@
 
     % Shorter version of `initPTB.m`
 
-    % Skip the PTB sync test
-    Screen('Preference', 'SkipSyncTests', 2);
+    if cfg.screen.do
+
+        % Skip the PTB sync test
+        Screen('Preference', 'SkipSyncTests', 2);
 
-    % Open a transparent window
-    PsychDebugWindowConfiguration;
+        % Open a transparent window
+        PsychDebugWindowConfiguration;
 
-    % Here we call some default settings for setting up Psychtoolbox
-    PsychDefaultSetup(2);
+        % Here we call some default settings for setting up Psychtoolbox
+        PsychDefaultSetup(2);
 
-    % Get the screen numbers and draw to the external screen if avaliable
-    cfg.screen.idx = max(Screen('Screens'));
+        % Get the screen numbers and draw to the external screen if avaliable
+        cfg.screen.idx = max(Screen('Screens'));
 
-    % Open an on screen window
-    [cfg.screen.win, cfg.screen.winRect] = Screen('OpenWindow', cfg.screen.idx, cfg.color.background);
+        % Open an on screen window
+        [cfg.screen.win, cfg.screen.winRect] = Screen('OpenWindow', cfg.screen.idx, cfg.color.background);
+
+        % Get the size of the on screen window
+        [cfg.screen.winWidth, cfg.screen.winHeight] = WindowSize(cfg.screen.win);
+
+        % Get the Center of the Screen
+        cfg.screen.center = [cfg.screen.winRect(3), cfg.screen.winRect(4)] / 2;
+
+        % Query the frame duration
+        cfg.screen.ifi = Screen('GetFlipInterval', cfg.screen.win);
+
+        % Get monitor refresh rate
+        cfg.screen.monitorRefresh = 1 / cfg.screen.ifi;
+
+        % Set up alpha-blending for smooth (anti-aliased) lines
+        Screen('BlendFunction', cfg.screen.win, 'GL_SRC_ALPHA', 'GL_ONE_MINUS_SRC_ALPHA');
+
+    end
+
+end
+
+function cfg = devSandbox_initAudio(cfg)
+
+    if cfg.audio.do
+
+        InitializePsychSound(1);
+
+        cfg.audio.pahandle = PsychPortAudio('Open', ...
+            [], ...
+            [], ...
+            [], ...
+            cfg.audio.fs, ...
+            cfg.audio.channels);
+
+    end
+end
 
-    % Get the size of the on screen window
-    [cfg.screen.winWidth, cfg.screen.winHeight] = WindowSize(cfg.screen.win);
+function cfg = devSandbox_computePpd (cfg)
 
-    % Query the frame duration
-    cfg.screen.ifi = Screen('GetFlipInterval', cfg.screen.win);
+    % Computes the number of pixels per degree given the distance to screen and
+    % monitor width. This assumes that the window fills the whole screen
 
-    % Set up alpha-blending for smooth (anti-aliased) lines
-    Screen('BlendFunction', cfg.screen.win, 'GL_SRC_ALPHA', 'GL_ONE_MINUS_SRC_ALPHA');
+    cfg.screen.FOV = 180 / pi * 2 * atan(cfg.screen.monitorWidth / (2 * cfg.screen.monitorDistance));
+    cfg.screen.ppd = cfg.screen.winWidth / cfg.screen.FOV;
 
 end
 
diff --git a/tests/test_setDefaultsPTB.m b/tests/test_setDefaultsPTB.m
index 7db37ed..b7aefc3 100644
--- a/tests/test_setDefaultsPTB.m
+++ b/tests/test_setDefaultsPTB.m
@@ -65,7 +65,7 @@ function test_setDefaultsPtbAudio()
         'color',  struct( ...
         'background', [0 0 0]), ...
         'text', struct('font', 'Courier New', 'size', 18, 'style', 1));
-    
+
     expectedCFG.screen.monitorWidth = 42;
     expectedCFG.screen.monitorDistance = 134;
     expectedCFG.screen.resolution = {[], [], []};