Acoustics · 8 min read
Acoustic phone booths: a buyer’s guide for workplace leads
NRC, Dn,e,w, ISO 23351-1 — the three measurements that should drive your phone-booth shortlist. Plus the install-time question most procurement teams forget.
Published September 26, 2025
The two acoustic numbers that matter
Inside the booth: NRC (Noise Reduction Coefficient). Measures how much the interior absorbs to keep your call intelligible to the person on the line. NRC 0.85+ is contract-grade. Below 0.7 sounds like a phone box.
Between booth and office: Dn,e,w under ISO 23351-1. Measures how much sound the booth blocks from leaking out (and in). 30 dB is acceptable for open-plan call use; 35 dB is contract-grade and required by most institutional bid sheets.
The install-time question nobody asks
A booth that needs four people, a forklift and 4 hours to install adds USD 600–1,200 of shipped-cost on the project P&L per unit, on top of the booth itself. OBJEKT booths install with two people and hex tools in 50–60 minutes — verified with non-trade installers on a 4-unit pilot.
Free-standing vs. fixed: a depreciation note
Free-standing booths (no anchor to floor or ceiling) are accounted as FF&E and depreciate over 5–7 years. Fixed acoustic rooms are leasehold improvements and depreciate over the lease term (often 10+ years). For tenants on flex leases, free-standing is almost always the better cash-flow choice.