What are some alternatives?
When comparing EarTrumpet and Background Music, you can also consider the following products
Volume2 - Volume2 is an advanced Windows audio mixer, a complete replacement for the standard Volume Control.
Power mixer - Power Mixer is a complete Windows volume control replacement.
Audio Sliders - Volume Control replacement that is five times smaller than its Windows counterpart.
Volumouse - From authors website:
Sound Control - App-specific volume control
Volti - Volti is an GTK+ application for controlling audio volume from system tray/notification area.