The word "echoey" is usually used to describe sounds that reverberate or bounce back. However, there are several synonyms to refer to this type of sound. The first synonym is "resonant" which suggests a sound with a deep or full tone. Another synonym is "reverberant" which implies that the sound persists for a long time due to multiple reflections. "Ringing" is also a suitable synonym, especially when referring to a high-pitched sound that lingers in the air. Finally, "haunting" can be used to describe an echoey sound that gives a spooky feeling. In conclusion, these synonyms help to add variety and depth to descriptions of sounds that are characterized as "echoey".