Field Story

Failing BB93: The Auditorium That Could Not Graduate

A new school auditorium failed its BB93 acoustic assessment with RT60 of 1.9 seconds at 500 Hz against the 1.0-second requirement. The building could not receive its occupancy certificate. Impulse response measurements across 6 receiver positions confirmed the issue. Installing Class A absorbers on 35% of the rear wall and ceiling clouds above the seating brought RT60 to 0.95 seconds, passing the standard.

School Auditorium

EQ Recommendation per ISO 3382-2

TL;DR

ISO 3382-2 reverberation data from ordinary rooms provides essential context for EQ recommendations. In rooms like classrooms, conference rooms, and restaurants, the RT60 profile determines how much EQ can effectively improve the sound. SonaVyx AI diagnostic engine incorporates per-band RT60 values from ISO 3382-2 measurements to generate EQ recommendations that acknowledge the room acoustic limitations. For example, in a classroom with RT60 of 1.2 seconds at 500 Hz, the engine recommends conservative low-mid EQ and suggests acoustic treatment rather than electronic compensation for the excess reverberation.

Room Context for EQ

ISO 3382-2 measurements in ordinary rooms reveal the acoustic environment that your EQ must work within. Understanding this context prevents unrealistic EQ decisions.

RT60 and EQ Limits

  • Rooms with RT60 above 1.5 seconds have significant reverberant energy that EQ cannot remove
  • EQ boost adds energy to both the direct and reverberant fields
  • Net benefit diminishes as RT60 increases
  • Acoustic treatment is recommended when RT60 exceeds 1.5x the target for the room type

Band-Specific Strategy

  1. Low frequencies (125-250 Hz): if RT60 exceeds mid-frequency RT60 by 50%, reduce LF energy via EQ
  2. Mid frequencies (500-2000 Hz): the speech-critical range, optimize carefully based on measured response
  3. High frequencies (4000-8000 Hz): usually short RT60, EQ boost can improve clarity effectively
  4. Match EQ strategy to the frequency-dependent absorption characteristics of the room

Room Type Considerations

Different room types have different optimal approaches: classrooms need speech clarity, conference rooms need natural voice quality, and restaurants need controlled background level.

Common Mistakes

  • Applying identical EQ strategy regardless of room type and RT60
  • Boosting mid-frequency EQ in reverberant rooms
  • Not measuring RT60 before making EQ decisions

SonaVyx Tools

Get room-aware EQ from the SonaVyx AI diagnostic. Measure RT60 with the RT60 tool. Check response with the transfer function. Verify levels with the SPL meter. Calculate treatment needs at AcousPlan. See our learning modules for EQ fundamentals.

Standard Reference

ISO 3382-2:

Try It Now

Open this measurement tool in your browser — free, no download required.

Open Tool
AP

Design your room acoustics with AcousPlan

acousplan.com →

Last updated: March 19, 2026