The Auralize CO₂ Tolerance Test

What the test actually does

The browser guides five calm warm-up breaths. On the next cycle, you take one gentle inhale and begin a slow, soft exhale. The timer records how long you sustain that exhale before you press Stop and return to ordinary breathing. The interface then places the duration into an Auralize level and can save the result as a personal baseline.

Earlier descriptions of this page called it an exhale-then-hold test. That is not the current protocol. There is no breath-hold phase, and comparing the raw score with BOLT produces a false equivalence. This page documents the live controlled-exhale assessment.

How to take it consistently

Sit upright with both feet supported. Complete the warm-up without deliberately taking maximal breaths. When the scored cycle starts, inhale comfortably rather than filling to total lung capacity. Let the exhale remain quiet and even. Stop when you need to inhale; do not squeeze the abdomen or throat to extend the final seconds.

For a retest, keep posture, time of day, warm-up, and stopping rule as similar as possible. Recent hard exercise, respiratory illness, congestion, anxiety, meal timing, and familiarity with the task can change the result. A trend from several comparable tests is more informative than one unusually high score.

What the five levels mean

The levels are Auralize product categories derived from controlled-exhale duration. They help the app choose pacing and describe change inside this specific training system. They are not population norms, diagnostic categories, or validated cutoffs for respiratory disease. A higher level means a longer controlled exhale under this protocol—nothing more should be inferred automatically.

Why the name needs a limitation

Carbon dioxide and pH strongly influence respiratory drive, but a browser timer cannot isolate that physiology. Exhale duration also depends on starting volume, airflow, respiratory mechanics, technique, motivation, and the stop decision. “CO₂ tolerance” is the product’s training label for the baseline, not a claim that Auralize measured arterial partial pressure of carbon dioxide.

How it differs from BOLT

BOLT begins after a normal exhale and times a pause until the first clear urge to breathe. The Auralize CO₂ test times the exhale itself. Because the tasks and stopping rules differ, do not convert one score into the other or assume a fixed gap. Use the dedicated BOLT route if a first-urge hold is the metric you intend to track.

How Auralize uses the result

If you save the result as an active baseline, Auralize may use it to suggest a box-breathing interval and configure the CO₂ Capacity Builder. Those are product heuristics designed to keep practice progressive. They have not been clinically validated as treatment dosing, and comfort and safety override the suggested pace every time.

Safety and exclusions

Stay seated and stop at the first need to inhale. Return to normal breathing if you feel dizzy, strained, or distressed. Do not perform the assessment while driving, standing at height, or in water. Seek medical advice before respiratory testing if you are pregnant, prone to fainting, or have significant heart, lung, or neurological disease. New or severe breathing symptoms need clinical assessment rather than an app score.