Most segmental speech errors probably are articulatory blends of competing segments. Perceptual consequences were studied in listeners' reactions to misspoken segments. 291 speech fragments containing misspoken initial consonants plus 291 correct control fragments, all stemming from earlier SLIP experiments, were presented for identification to listeners. Results show that misidentifications (i.e. deviations from an earlier auditory transcription) are rare (3%), but reaction times to correctly identified fragments systematically reflect differences between correct controls, undetected, early detected and late detected speech errors, leading to the following speculative conclusions: (1) segmental errors begin their life in inner speech as full substitutions, and competition with correct target segments often is slightly delayed; (2) in early interruptions speech is initiated before competing target segments are activated, but then rapidly interrupted after error detection; (3) late detected errors reflect conflict-based monitoring of articulation or monitoring overt speech.