Minimal pair words differ by a single phoneme. Which acoustic cue helps the listener perceive the difference between words like ‘pea’ and ‘bee’?

• A. Spectrum of the aperiodic noise associated with the stop
• B. Voice onset time (interval between release burst and onset of voicing)
• C. Steepness of the formant transition between the consonant and the vowel
• D. Amplitude of the energy peak in the vowel

Answer: (B)

The key idea is how listeners hear voicing in a start consonant. When you say pea vs bee, the crucial cue is the timing between the release of the consonant and when the vocal folds start vibrating—voice onset time, or VOT. For a voiceless aspirated stop like the initial sound in “pea,” voicing starts after a noticeable delay, so the VOT is longer. For a voiced stop like the initial sound in “bee,” voicing begins almost immediately after release, giving a very short VOT. Our perceptual system uses this timing difference to distinguish the two words reliably.

Other cues exist—such as the spectrum of the release, how the vowel formants shift at the consonant–vowel boundary, or how strong the vowel’s energy peak is—but they don’t carry the primary voicing difference as effectively as VOT does. So the timing between release and voicing onset is the best acoustic cue for telling these two apart.