The TinyDB only stores text. The TinyDB can not store sound files although it can record links to sound files stored in Media (Assets) on GoogleDrive or a server for example or in the Internal storage of the device.
The following will help you code your assignment.
Recording a sound is easy , do Taifun's tutorial How to use the Sound Recorder. It shows the directory the sound bite is stored in using the AfterSoundRecorded Block..Use that directory information to provide a link to the sound file that has an autogenerated file name.
What coding have you done so far? Provide some Blocks and someone will certainly provide some specific advice.