Sports Tracker uses Siri for voice audio feedback.
To modify the Siri settings go to:
1. Phone settings - Siri& Search
(eg. you can choose the gender in Siri Voice. Note this is not supported in all Languages)
2. Phone settings - Siri& Search  -scroll down to apps - Sports Tracker. 
3. If you want Sports Tracker to react on Siri commands go in app to Profile -Settings- Siri - Enable