Speech Intelligibility in Home Cinemas - June 18th, 2009
Most home cinemas suffer from poor speech intelligibility. Lyrics in songs lose their meaning and movie plots are confusing; does this sound familiar? Reflections generated in small listening spaces contribute to degraded dialog intelligibility, creating a very unpleasant listening experience.
Speech intelligibility is a quite interesting topic, especially if one takes into consideration that early reflections support the direct sound and are necessary. However, in home cinema design and all custom home cinema installations, one would have to investigate the subject a bit further. Various authors have investigated the effect of early reflections in regards to their level and delay from the direct sound. One can derive to the conclusion that intelligibility progressively improves in home theatre applications as the delay of a single reflection is reduced and the listener would perceive a stronger ’summed’ sound.
Further investigation in small listening spaces like a home cinema room proved that the biggest issue with speech intelligibility is the signal-to-noise ratio. Noisy air conditioning systems and noise bleeding from the adjacent rooms greatly degrades the result. In other words, “more noise, less intelligible speech”.