It could be that you’re using an earplug that’s too small or that your Autditio is not placed properly in your ear; this can cause a temporary whistling tone. Also if, for example, you hold a phone next to the ear that has the Auditio in it, short whistle tones may occur in case of strong amplification. If you hold your hand still, the whistle tone will disappear and you can make your phone call.