1. A non-transitory processor-readable medium storing code representing instructions to be executed by a processor, the code comprising code to cause the processor to: record a reference speech sample spoken by a native speaker; record a student speech sample spoken by a language student; generate a reference digital data file representative of the reference speech sample and a student digital data file representative of the student speech sample, the reference digital data file including information indicative of a sound intensity level as function of time over a chronological duration of the reference speech sample and the student digital data file including information indicative of a sound intensity level as a function of time over a chronological duration of the student speech sample; segment the reference digital data file into a reference speech-unit data file and the student digital data file into a student speech-unit data file, the reference speech-unit data file including a plurality of reference speech-units from the reference digital data file over a reference speech sample duration and the student speech-unit data file including a plurality of student speech-units from the student digital data file over a student speech sample duration; and generate a plurality of student speech-unit duration differences by calculating a difference in duration between each student speech-unit from the plurality of student speech-units and the remaining speech-units from the plurality of student speech-units.