Plain-language definitions of the audio terms used throughout this guide.
Terms
| Term | Definition |
|---|---|
| Alignment | Adjusting level, timing (delay) and polarity so your speakers and subwoofer work together as one system rather than fighting each other. |
| All-pass filter | A filter that changes timing (phase) at certain frequencies without changing loudness. Used by the optional Phase Correction step. |
| Averaging | Smoothing the live measurement over time so the curve is steadier and easier to read. Slow / Fast / Ultra-Fast are smooth rolling averages. FIFO modes average exactly the last few measurement frames (see Appendix A — Reference tables). |
| Bypass | Turning a filter, band, or the whole correction off temporarily without deleting it, so you can compare with and without. |
| Coherence | A per-frequency measure (0–100%, shown as Confidence) of how much of what the mic heard was actually the test signal, versus noise and reflections. High coherence = trustworthy data. |
| Crossover | The frequency where sound is split between speakers: below it goes to the subwoofer (low-pass), above it goes to the main speakers (high-pass). |
| Delay | A small, deliberate time offset added to an output so all speakers' sound arrives at your ears together. Also expressible as distance. |
| dB (decibel) | The unit of loudness/level. 0 dB means “no change”. Negative is quieter, positive is louder. |
| DSP (Digital Signal Processing) | The processing inside your device that changes the sound: gain, delay, crossover, EQ. |
| Firmware | The software that runs on the device itself (separate from the Omnissiah app on your computer). Kept up to date via OTA updates. |
| GCC-PHAT | A method for finding the time delay between two signals by looking for the peak of their cross-correlation. One of the delay-estimation options. |
| High-pass / Low-pass | A high-pass filter lets high frequencies through and rolls off the lows. A low-pass does the opposite. The two halves of a crossover. |
| Loopback | Routing your computer's own audio (music, films) back into the app through a virtual audio device, so it can be corrected in real time. |
| OTA (Over-The-Air) update | Updating the device's firmware through the app over USB, without special tools. |
| Parametric EQ (PEQ) | An equaliser where each band has an adjustable frequency, gain and Q (width), letting you shape the response precisely. |
| Phase correction | An optional calibration step (off by default) that fine-tunes the remaining timing differences between speakers with all-pass filters, after delay alignment. |
| Pink noise | A test signal with equal energy per octave, used to measure a system's frequency response. It sounds like a steady “shhh”. |
| Polarity (phase invert) | Flipping the waveform of an output. Wrong relative polarity between the sub and mains makes bass sound thin at the crossover. |
| Q | The width of an EQ band. Low Q is wide and gentle. High Q is narrow and surgical. |
| Room mode | A resonance caused by your room's dimensions, making certain bass notes much louder (a peak) or, where waves cancel, much quieter (a null). |
| Null | A deep dip caused by sound waves cancelling out at your listening position. Nulls can't be fixed by boosting EQ, only by moving speakers, sub or seat. |
| Sample rate | How many times per second the audio is measured (e.g. 48,000 = 48 kHz). Higher captures more detail. |
| Snapshot | A saved measurement you can name, colour, compare and export. |
| SNR (Signal-to-Noise Ratio) | How far your measurement rose above the room's background noise. Higher is a cleaner, more reliable measurement. |
| Target curve | The tonal balance the correction aims for. Flat is neutral. A gentle bass lift (like Tantrum Flat) usually sounds fuller and more natural. |
| Time-align | See Alignment. Time-aligning is the delay part of it, making sound from each speaker arrive together. |
