Three acoustic problems account for the majority of room sound issues — and each has a different cause and a different fix. Flutter echo is a rapid, repeating echo caused by sound bouncing between two parallel reflective surfaces (typically two facing walls). You can identify it by clapping once in a room and listening for a "slapback" or "ticking" decay. Standing waves (room modes) are frequency-specific pressure buildups at particular positions in the room caused by the room's dimensions creating constructive interference at certain wavelengths. They make bass sound boomy in some positions and thin in others. Reverberation is the accumulation of all reflected sound what gives rooms a "live" or "dead" character. Each of these problems requires a different treatment approach: flutter echo responds to absorption on facing walls; standing waves require bass traps and broadband low-frequency absorption at boundaries; reverberation requires coverage-area absorption and diffusion. An acoustic measurement identifies which of these problems is dominant in your space.