A system and method for generating frequency-multiplexed synthetic sound-speech stimuli and for detecting and analyzing electrical brain activity of a subject in response to the stimuli. Frequency-multiplexing of speech copora and synthetic sounds helps the composite sound to blend into a single auditory object. The synthetic sounds are temporally aligned with the utterances of the speech corpus. Frequency multiplexing may include splitting the frequency axis into alternating bands of speech and synthetic sound to minimize the disruptive interaction between the speech and synthetic sounds along the basilar membrane and in their neural representations. The generated stimuli can be used with both traditional and advanced techniques to analyze electrical brain activity and provides a rapid, synoptic view into the functional health of the early auditory system, including how speech is processed at different levels and how these levels interact.