Narrative:

Shortly after leveling off at our cruising altitude captain; who was PF (pilot flying); assumed control of the radios while I; pm (pilot monitoring); took a few minutes to eat a crew meal. During this short period captain queried ATC asking for an altitude change to a lower; and hopefully smoother; altitude. After his request; an ATC supervisor keyed in asked him if 'everything was okay' and it 'sounds like you're slurring your words'. Captain said everything was fine and that we were just getting bounced around due to the ride conditions. I finished my meal; returned to working the radio; and we landed uneventfully. Due to an aircraft swap; we had to exit security to transition to another terminal. Once outside security; captain made several calls to the ZZZ chief pilots; duty pilot; and [company] for guidance on how to handle the situation. We didn't want to show up to our next aircraft with ATC thinking we weren't fit to fly. With helpful information from all available resources it was determined that two managers would meet us to assess captain fitness for duty through a series of questions. The questions were administered and we were cleared to board the aircraft and work our last leg of the night back to ZZZ1.captain's voice; slight accent; and the ride conditions attributed to ATC's questioning. While I do not know what controllers are trained to listen for specifically; I understand that if they were concerned about our well-being that they would ask the questions they did. Simply; captain could annunciate more and be clearer when using the radio. ATC could have explained what they were asking about in a little more detail.

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Original NASA ASRS Text

Title: EMB-190 flight crew reported ATC Controller suspected slurred speech by Captain.

Narrative: Shortly after leveling off at our cruising altitude Captain; who was PF (Pilot Flying); assumed control of the radios while I; PM (Pilot Monitoring); took a few minutes to eat a crew meal. During this short period Captain queried ATC asking for an altitude change to a lower; and hopefully smoother; altitude. After his request; an ATC supervisor keyed in asked him if 'everything was okay' and it 'sounds like you're slurring your words'. Captain said everything was fine and that we were just getting bounced around due to the ride conditions. I finished my meal; returned to working the radio; and we landed uneventfully. Due to an aircraft swap; we had to exit security to transition to another terminal. Once outside security; Captain made several calls to the ZZZ Chief Pilots; Duty Pilot; and [Company] for guidance on how to handle the situation. We didn't want to show up to our next aircraft with ATC thinking we weren't fit to fly. With helpful information from all available resources it was determined that two managers would meet us to assess Captain fitness for duty through a series of questions. The questions were administered and we were cleared to board the aircraft and work our last leg of the night back to ZZZ1.Captain's voice; slight accent; and the ride conditions attributed to ATC's questioning. While I do not know what Controllers are trained to listen for specifically; I understand that if they were concerned about our well-being that they would ask the questions they did. Simply; Captain could annunciate more and be clearer when using the radio. ATC could have explained what they were asking about in a little more detail.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.