this is a defintion of voice matching i found from crutchfieldadvisor.com
however I just cant wrap my head around which specs I should be looking for
Voice-matching
When speakers possess a similar timbre or tonal quality. Voice-matched (or timbre-matched) speakers in a home theater system will result in more seamless, consistent, convincing wraparound sound. A good way to get voice-matched speakers is to stay within a family or series of speakers from a single manufacturer, or to get a pre-matched multi-speaker system.