You prefer it as a new tab? Disable "Reuse tab" in the preferences.

Are you sure your sound is turned on? The speak action is limited to 195 characters, it will tell you that if you try to speak more than 195 characters.

If you want speak action to only speak, use the checkbox "Use audio only for Google Translate Voice" in the preferences.

If you have other suggestions, please file a new issue on GitHub. https://github.com/Smile4ever/firefoxaddons/issues

If any of these remarks helped you, please consider updating your review.