Module 1 — Sound & audio fundamentals

Sound is air-pressure variation over time. Frequency (Hz) = pitch; human hearing spans roughly 20 Hz–20 kHz. Amplitude = loudness, measured in decibels (dB) — a logarithmic scale: +6 dB doubles voltage, +10 dB sounds roughly twice as loud. Wavelength shortens as frequency rises; bass waves are meters long, which is why small rooms fight low end.

dBFS — digital full scale; 0 dBFS is the absolute ceiling, everything is negative. dBu/dBV — analog voltage references. SPL — acoustic level in the room. Line level: +4 dBu pro, -10 dBV consumer. Mic level is tiny (~-50 dBu) and needs a preamp.

Dynamic range = distance between noise floor and ceiling. Headroom = safety space above your average level. Broadcast practice: peak music around -6 to -3 dBFS, keep average way lower. When AMEL's mount got seized by a stray webcam session, the giveaway was a mean level around -15 dB LOW and muffled — level discipline is a diagnostic tool, not decoration.

Every track in the Network Media Library carries a duration and rides AutoDJ level management on AzuraCast. When one file sounds quiet next to the rest of rotation, it's usually mastering level, not the station — check the file before you blame the transmitter chain.