An SLP asks a listener to identify the word “pie” when presented with words that start with different voice-onset-times. Six responses are obtained for each of the following VOTs: VOT = −20, 0/6 = pie; VOT = −10, 0/6 = pie; VOT = 0, 1/6 = pie; VOT = +10, 2/6 = pie; VOT = +20, 4/6 = pie; VOT = +30, 6/6 = pie. What VOT value corresponds to this listener’s perceptual category boundary between “pie” and “bye”?

An SLP asks a listener to identify the word “pie” when presented with words that start with different voice-onset-times. Six responses are obtained for each of the following VOTs: VOT = −20, 0/6 = pie; VOT = −10, 0/6 = pie; VOT = 0, 1/6 = pie; VOT = +10, 2/6 = pie; VOT = +20, 4/6 = pie; VOT = +30, 6/6 = pie. What VOT value corresponds to this listener’s perceptual category boundary between “pie” and “bye”?

• A. −20 ms VOT
• B. 0 ms VOT
• C. 15 ms VOT
• D. +30 ms VOT

Answer: (C)

Perceptual category boundary is the VOT where the listener is equally likely to hear either category, here pie or bye. Looking at the data, pie responses are 2 out of 6 at +10 ms and 4 out of 6 at +20 ms. The 50% point lies halfway between these two, so the boundary occurs at +15 ms VOT. This is the VOT value where the listener would be about equally likely to identify the sound as pie or bye.

Perceptual category boundary is the VOT where the listener is equally likely to hear either category, here pie or bye. Looking at the data, pie responses are 2 out of 6 at +10 ms and 4 out of 6 at +20 ms. The 50% point lies halfway between these two, so the boundary occurs at +15 ms VOT. This is the VOT value where the listener would be about equally likely to identify the sound as pie or bye.