Many students do not realize there is a difference between "comprehensibility" and "intelligibility" of speech although in the "real world" they are used interchangeably. A person who is comprehensible is readily understood because of the listener's familiarity to either them, the topic being discussed, or added cues such as gesture or familiar dialect. Intelligibility in my field has to do strictly with articulation. I have come across people who perfectly pronounce all of their words, but because they speak too quickly or too low, they are not comprehensible (readily understood by the listener). In this short segment, I would encourage you to record yourself and see if your rate might have a negative impact on how your words are understood. For those who find they are moving too quickly, I will share a quick and dirty tip for naturally slowing down without thinking "okay well I better slow down".
TIP: EMPHASIZE the ending consonants of all your words! Look at this sentence: The magazine is in the bookcase. I naturally slow down if I over-exaggerate and over-articulate the endings >> ThUH - magga-ZEEN - iZ -iN- thUh - buh-KAYY-SSS >> and there is a nice way of monitoring the rate and making certain endings of words do not get cut off. In many cases this can increase comprehensibility (as well as intelligibility) of the intended message of the speaker!