// write as3 code here..
// 1〜7のキーボードで鍵盤

package {
 
 import flash.display.Sprite;
 import flash.filters.BlurFilter;
 import flash.media.Sound;
 import flash.media.SoundChannel;
 import flash.events.Event;
 import flash.events.KeyboardEvent;
 import flash.events.SampleDataEvent;
 import flash.events.TimerEvent;
 import flash.text.TextField;
 import flash.utils.Timer;
 
 
 public class Main extends Sprite {
 
 public const snd:Sound = new Sound();
 public const wrapper:Sprite = new Sprite(); 
 public const g:Sprite = new Sprite(); 
 public const t:TextField = new TextField();
 public const keys:Array = [0,2,4,5,7,9,11];
 public const tones:Array = ["ド","レ","ミ","ファ","ソ","ラ","シ"];
 public var ch:SoundChannel;
 public var tone:Number = 1;
 
 public function Main() {
 //配置
 addChild(wrapper);
 wrapper.addChild(g);
 wrapper.filters = [new BlurFilter(8,8,1)];
 addChild(t);
 //Text
 t.selectable = false;
 t.width = 300;
 t.height = 300;
 t.htmlText = "!";
 t.x = (stage.stageWidth-t.width)/2;
 t.y = (stage.stageHeight-t.textHeight)/2;
 //描画
 g.graphics.beginFill(0x660066);
 g.graphics.drawRect(0,0,10,10);
 g.graphics.endFill();
 //音
 snd.addEventListener(SampleDataEvent.SAMPLE_DATA, onSampleData);
 //キーボード
 stage.addEventListener(KeyboardEvent.KEY_DOWN,onKeyDown);
 stage.addEventListener(KeyboardEvent.KEY_UP,onKeyUp);
 }
 
 private function onKeyDown(e:KeyboardEvent):void {
 var n:Number = e.keyCode - 48;
 if ( n < 1 || n > keys.length ) return;
 tone = (1+keys[n-1]/12)/2;
 if ( ch ) ch.stop();
 ch = snd.play();
 t.htmlText = ""+tones[n-1]+"";
 }
 private function onKeyUp(e:KeyboardEvent):void {
 var n:Number = e.keyCode - 48;
 if ( n < 1 || n > keys.length ) return;
 ch.stop();
 t.htmlText = "!";
 }

private function onSampleData(event:SampleDataEvent):void {
 for (var c:int=0; c<8192; c++) {
 var rad:Number = (Number(c+event.position)*tone/Math.PI);
 var amp:Number = Math.sin(rad) / 4; // -1 から 1 の間の値なら OK
 event.data.writeFloat(amp); // 左チャネルの音
 event.data.writeFloat(amp); // 右チャネルの音
 }
 }
 }
}

Sound Test