B737 captain reported a flight attendant was injured during a wake turbulence encounter at FL340.

Attributes
ACN	1440422
Time
Date	201704
Local Time Of Day	1801-2400
Place
Locale Reference	ZOB.ARTCC
State Reference	OH
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	Cruise
Flight Plan	IFR
Person 1
Function	Pilot Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 800 Flight Crew Total 24000 Flight Crew Type 11182
Events
Anomaly	Flight Deck / Cabin / Aircraft Event Illness Inflight Event / Encounter Wake Vortex Encounter

Narrative:

While at cruise [a] flight attendant was hurt when the aircraft [encountered] wake turbulence at FL340. It only lasted a second but it went from smooth calm air to moderate turbulence back to calm in seconds. [The flight attendant] said she was fine afterwards but the next day she decided to file a report.

Original NASA ASRS Text

Title: B737 Captain reported a Flight Attendant was injured during a wake turbulence encounter at FL340.

Narrative: While at cruise [a] Flight Attendant was hurt when the aircraft [encountered] wake turbulence at FL340. It only lasted a second but it went from smooth calm air to moderate turbulence back to calm in seconds. [The Flight Attendant] said she was fine afterwards but the next day she decided to file a report.

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.