In this demonstration, a segment of speech is processed by the linear shift invariant system studied in the previous demonstration. It is "filtered" by a low-pass filter which attenuates frequencies above about 800 Hz. You hear that the speech sounds more muffled. The "crispness" in the sound is gone.
We also demonstrate the results of filtering speech with a high-pass filter that attenuates frequencies below about 800 Hz. This results in speech that is distinctly "crisp", but lacks body.