Custom definitions for AudioAnalyzer. (#1180)

Added custom definitions for both `GetSpectrum()` and `Changed`.

include/customDefinitions.d.ts

@@ -66,6 +66,14 @@ interface Attachment extends Instance {
 	WorldCFrame: CFrame;
 }
 
+interface AudioAnalyzer extends Instance {
+	/**
+	 * Returns the frequency spectrum of the last audio buffer, as an array of numbers. The elements of the array are root-mean-square volume levels, evenly spaced from 0 hertz to 24,000 hertz.
+	 * @returns number[512]
+	 */
+	GetSpectrum(this: AudioAnalyzer): Array<number>;
+}
+
 interface AvatarEditorService extends Instance {
 	GetAvatarRules(this: AvatarEditorService): AvatarRules;
 	GetBatchItemDetails(