Apple Watch Ultra 4 review: a more accurate heart sensor, 50-hour battery life, and new AI audio features
S11 chip checks heart rate every 5 seconds, HRV sampled 24x more often, plus a Readiness Score and four Audio Intelligence features; Thai price 29,900 baht
By Apple · Thursday, September 10, 2026 · 3 min read
Key point — The Apple Watch Ultra 4 upgrades its heart sensor (S11 measures every 5 seconds, HRV +24x), general battery life to 50 hrs / Max Extended Workout to 45 hrs, and adds 4 AI audio features, priced at 29,900 baht in Thailand.
Why it matters — On-device audio processing (in the S11's Secure Exclave) that deletes audio immediately is the privacy approach Apple is positioning as a differentiator.
Vs. Ultra 3 — Heart measurement frequency and battery life both improve significantly, while the AI audio features are entirely new.
Source: Apple
