A lecture recording workflow has to survive fifty repetitions, a flat battery and a room with bad acoustics. Anything that requires setup at the start of a class will eventually be skipped, and a semester with three missing weeks is worse than a semester of merely average audio. The workflow below is deliberately boring.
The fixed rig
One laptop, one phone, one USB cable, one stand, one power bank. Everything lives in the lectern bag so nothing is improvised. The software side is installed once and never reconfigured: the desktop client is set to start with Windows, and the phone app opens to a single Start button.
- USB cable, not Wi-Fi: a cable cannot be blocked by campus network policy
- Phone stand so the microphone sits at a consistent distance
- Power bank because a three-hour seminar exceeds most phone batteries
The thirty-second pre-flight
Plug the phone in, confirm the client shows Connected, speak one sentence and watch the level meter. If the meter moves, you are recording. This check catches the only two failures that actually occur in practice: the cable is not fully seated, and the app was closed by a battery optimiser overnight.
| Check | Pass condition | If it fails |
|---|---|---|
| Cable seated | Client shows Connected | Reseat at both ends, try another cable |
| App running | Phone shows streaming | Reopen app, disable battery optimisation |
| Level meter | Moves when you speak | Check input device selection in Windows |
| Disk space | Above 2 GB free | Record to an external drive |
File naming done at capture time
Rename afterwards never happens. Set the recorder to write COURSE-YYYY-MM-DD-lectureNN.wav before the first class and never change the pattern. The ISO date sorts correctly as text, which means the archive remains usable when it moves between drives and when the folder is opened five years later.
- WAV or FLAC, never MP3 for the master
- One file per lecture, no pausing and resuming
- Copy to cloud storage the same day, not the same week
Positioning that works in a real lecture theatre
The phone goes on the lectern, 20 to 30 cm from the speaker's mouth, angled slightly off axis. Do not put it in a pocket: fabric muffles high frequencies and the result sounds like a phone call from 2004. If you move around while teaching, a lanyard clip is better than a stand, at the cost of some handling noise.
- 20-30 cm from the mouth, off axis to reduce plosives
- Never inside a pocket or bag
- Aim away from the projector fan, which produces a constant 200 Hz hum
Levels and processing
Aim for peaks around minus 12 dB. Students listen on earbuds and laptop speakers, so clarity matters more than loudness, and headroom prevents clipping when you raise your voice. Apply a gentle high-pass filter at 80 Hz to remove desk thumps and projector rumble, and nothing else. Compression makes quiet passages louder and makes a lecture harder to follow, not easier.
| Stage | Setting | Reason |
|---|---|---|
| Capture | 48 kHz, 16-bit mono | Standard, no resampling later |
| Peaks | -12 dB | Headroom for raised voices |
| High-pass | 80 Hz | Removes desk and projector rumble |
| Compression | None | Preserves natural dynamics |
Handling questions from the room
Repeat every question into the microphone before answering. It solves the recording problem and the back-row problem at the same time, and it costs two seconds. Lecturers who adopt this habit stop receiving emails asking what the second half of the lecture was about.
- Repeat the question, then answer
- Pause for two seconds between topics so the recording has clear chapter boundaries
- Announce the slide number when you change topic; it makes the recording navigable
What to do when something breaks mid-lecture
Do not stop teaching to fix audio. The recording continues even if the phone disconnects, because the client keeps the file open and appends what it has. Fix the connection during the break and continue. A lecture with a two-minute gap is far more useful than no lecture. If the failure is persistent, the https://womic.io/wo-mic-pc/ covers the connection states and what each one means, which is faster than trial and error in front of a class.
Frequently Asked Questions
What if the room has no usable power?
A phone on a full charge records several hours over USB without drawing from the laptop, but keep a power bank in the bag for back-to-back seminars.
Should I record the projector audio too?
Yes, if the lecture includes video. Capture system audio on a second track rather than hoping the microphone picks up the speakers.
How large are the files?
Roughly 330 MB per hour at 48 kHz 16-bit mono. A full semester fits comfortably on a 64 GB drive.
Can students hear the difference between USB and Wi-Fi?
In a quiet room, no. In a lecture theatre with Wi-Fi contention, Wi-Fi produces audible dropouts that USB does not.
