SpeakUp? app for iPhone and iPad

SpeakUp?™ monitors your sound environment, and notifies you when you or the people around you are not speaking loudly enough. It is intended for conference calls on speakerphones, where remote parties have a hard time hearing the local conversation.
To adjust the required voice volume, touch the upper part of the speaker cone and slide the blue marker to the required setting.
To adjust the feedback volume, use the physical volume control on your device, or the slider on the second page.
To change the feedback message, use the picker on the second page.