diff --git a/index.d.ts b/index.d.ts
index d3901f8..07ce1c5 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -1,12 +1,16 @@
 import { Writable, WritableOptions } from 'stream';
 
-namespace Speaker {
+declare namespace Speaker {
     interface Options extends WritableOptions {
         readonly channels?: number;
         readonly bitDepth?: number;
         readonly sampleRate?: number;
         readonly lowWaterMark?: number;
         readonly highWaterMark?: number;
+        readonly device?: string;
+        readonly samplesPerFrame?: number;
+        readonly float?: boolean;
+        readonly signed?: boolean;
     }
 
     interface Format {
@@ -25,8 +29,8 @@ namespace Speaker {
  *
  * @param opts options.
  */
-class Speaker extends Writable {
-    constructor(opts?: Speaker.Options);
+export default class Speaker extends Writable {
+    constructor (opts?: Speaker.Options);
 
     /**
      * Closes the audio backend. Normally this function will be called automatically
@@ -54,6 +58,4 @@ class Speaker extends Writable {
      * @return whether or not is playable
      */
     public isSupported(format: number): boolean;
-}
-
-export = Speaker
+}
\ No newline at end of file