Mumbling Isn't Sloppy Or Careless Speaking - It's Data Compression (Science Says So!)

"[Data-compression] algorithms trim down the space needed to digitally store sounds and images by throwing out information that is redundant or doesn't add much to our perceptual experience — for example, tossing out data at sound frequencies we can't hear, or not bothering to encode slight gradations of color that are hard to see. The idea is to keep only the information that has the greatest impact. Mumbling — or phonetic reduction, as language scientists prefer to call it — appears to follow a similar strategy."

Article source here:Arts Journal