Maybe just change `Blockly.playAudio = function(name, opt_volume)` to `Blockly.playAudio = function(name, options)` and get rid of the new function.
Then you can change `Blockly.playAudio('whack', .5)` to `Blockly.playAudio('whack', {volume : .5})`

It's not that many files to change:

```
$user-> grep -r "playAudio" apps/ core/
apps//maze/maze.js:  Blockly.playAudio('whack', .5);
apps//maze/maze.js:    Blockly.playAudio('whack', .5);
apps//maze/maze.js:    Blockly.playAudio('win', .5);
core//block_svg.js:  Blockly.playAudio('delete');
core//block_svg.js:  Blockly.playAudio('click');
core//blockly.js:Blockly.playAudio = function(name, opt_volume) {
```