While the high L2 group sounded less accented, more comprehensible and more fluent than the low L2 group, the NS group performed better than both L2 groups in these measures.

Undue or long pauses, repetitions and false starts are dysfluencies imperceptible by listeners.

Since the NS group members had their fluency affected by additional cognitive demands of high workload conditions, fluency measures may be a good indicator of cognitive overload.

Both the amount of retained information and the listeners’ perception of speech are affected by the workload.

High cognitive workload worsens the speech production of low-proficiency L2 speakers.