I've been trialling integrated university lecture timetables in Google Calendar since last year, and it's been very useful so far. One of the added bonuses is that it's allowed me to automate lecture audio recordings on my phone; when a lecture calendar event is active, my phone records from the microphone and then stops at the end of the lecture event. It also gives the recording a filename based on the date, time, and module title. This has been achieved using Tasker, an excellent tool for Android automation.
First you'll want to create a task to start the the recording and to name it appropriately. We'll do this using the Record Audio action. Under the File field, type in the path to where you'd like to save the recording (in my case, I save them in a folder called AudioRecordings), followed by %DATE%TIME%CALTITLE. These are variables for current date, time and calendar event title.
Next you need an event to stop the recording. All you need here is the Record Audio Stop action.
Finally, you'll need to create a profile that's triggered by specific calendar events. To do this, create a new profile based on State, and search for Calendar Entry. Here you can specify how to determine that it's a lecture event. I've simply specified that the title should match the module that I want recorded. You could also specify that every event under a specific calendar account should trigger the audio recording task. Add the Record Lecture task as the main task, and the Stop Record Lecture task as the exit task. That's it.
Using default settings, a two-hour recording is about 12.5MB in size. During lectures I'll usually place my phone on my desk, with the microphone pointed towards the front of the room. Doing this allows me to be able to easily understand lecturers during playback of the recordings.
Disclaimer: please obtain permission from your lecturers prior to recording them.