attunr lets you choose the tuning standard — the reference note A that all other notes are based on. This shifts the entire scale up or down.

A440 Hz is standard Western tuning. Pianos, orchestras, and most recorded music use it. If you want familiarity, start here.

A432 Hz is often called "healing" or "natural" tuning. Slightly lower than A440, it's popular in sound healing and meditation music. Many people find it softer and easier to sing.

A444 Hz is slightly higher. It appears in some sacred and classical traditions and can feel brighter or more energising.

A528 Hz is associated with the "miracle tone" and the Heart chakra. Choosing this makes 528 Hz your reference A, shifting the whole scale accordingly.

Try each and keep the one that feels right. Tuning only affects voice-based mode — Absolute mode uses fixed frequencies.