Recording a lecture and actually reviewing it
Recording 90 minutes does not give you 90 minutes to listen again. Turning it into searchable text is what lets you go back to the few minutes that matter. This is how to record for that, and what to do afterwards.
Check first
Whether it is a university lecture or an industry seminar, ask whether recording is allowed. Some lectures forbid it, and some venues say no because of the copyright on the material. Without permission, none of the rest of this applies.
Where to sit, where to put the device
Distance to the speaker decides most of the quality. If you can sit near the front, everything afterwards gets easier. If only the back is free, do not lay the device flat on the desk — rest it on a bag or a book so it sits a few centimetres up, and it picks up far less desk-tapping and chair-creaking.
In a room with a PA system, slightly off-axis from a speaker is easier to understand than directly in front of it. Straight on, the sound can be strong enough to distort.
Settings
| Format | WAV, because the point is to transcribe it |
|---|---|
| Bit depth | 24-bit, to leave room for distant sounds such as questions from the floor |
| Channels | Mono. Half the size, and recognition is no different |
| Splitting | On. Do not leave 90 minutes as a single file — split every 30 |
An incoming call during the lecture stops the recording. Switch on airplane mode before it starts. Recording continues with the screen off.
What helps while it runs
If you take notes, write times, not content. One line saying "38 min — said this will be on the exam" is enough to jump straight there using the timestamps in the transcript. Copying down the content is the recording's job, and the effort is better spent listening.
Afterwards
- Transcribe the whole thing with a light model. Even 90 minutes finishes in a time you can wait out
- Summarise it, so the day comes down to a few lines
- Redo only the parts you will use for exams or quotes with a heavier model
Technical terms and names break. Keeping your own list of the course, the textbook and the people involved lets you fix them with a search and replace, and it pays off more with every session.
Finding things later
Rename recordings so that the name says what is in them rather than the date. Something like "07 — Second law of thermodynamics" turns up in the library search. Keep the transcripts as well and you can find them by a word from the middle of the text.
Questions
How long does transcribing 90 minutes take?
It depends on the device and the model. A light model usually finishes in less than real time; a heavy one can take longer than the recording itself. Start with the light one.
Can it capture the slides too?
Audio only. Keep the handout, or capture the slides separately with a screen recording or photos. Match them up afterwards using the times you noted.
Several lectures fill up the storage quickly
Once a recording is transcribed, keep the text and move the audio off the device or delete it. Text takes almost no space.