Description

This Standard is now Current and is currently under review by BSI

BS EN ISO 3382-2:2008 – Acoustics. Measurement of room acoustic parameters – Reverberation time in ordinary rooms

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BS EN ISO 3382-2:2008, titled “Acoustics — Measurement of room acoustic parameters — Part 2: Reverberation time in ordinary rooms,” outlines standardized methods for determining reverberation time in rooms typically used for speech and other activities, such as classrooms, offices, and residential spaces. The standard is specifically designed for spaces ranging in volume from 25 m³ to 250 m³.

Key Aspects of the Standard:

1. Purpose of Reverberation Time Measurement

Reverberation time is a critical parameter in room acoustics that directly impacts:

• Speech Intelligibility: Essential in environments like classrooms or meeting rooms.
• Acoustic Comfort: Influencing the quality of sound for both speech and music.
• Sound Control: Assessing the need for acoustic treatment in a space.

2. Measurement Techniques

The standard specifies methods for measuring reverberation time using:

• Impulse Sound Sources: Methods such as clapping hands, balloon bursts, or starter pistols to create an impulse response.
• Interrupted Noise Sources: Generating steady noise that is turned off abruptly, with measurements taken during the decay period. These methods aim to capture the time it takes for sound energy to decay by 60 dB (T60).

3. Frequency Bands

The measurements cover a wide range of frequencies, typically in one-octave or one-third octave bands, ensuring that reverberation time is assessed for both high and low frequencies, which can behave differently in a room.

4. Equipment Requirements

• Sound Source: Must produce consistent and omnidirectional sound energy.
• Microphones: Should have a flat frequency response and be placed at various locations within the room to capture spatial variations.
• Analyzers: Devices capable of accurately recording decay curves and calculating reverberation times.

5. Calculation and Data Analysis

• Decay Curve Analysis: Reverberation time is derived from the sound pressure level decay curve. Linear regression is applied to the decay curve within a defined range.
• Single-Value Summaries: The reverberation time is often averaged across frequencies or presented as T20 or T30 values (indicating measurements based on decay ranges of 20 dB or 30 dB, respectively).

6. Application of Results

Reverberation time measurements are used to:

• Compare rooms for compliance with acoustic standards or guidelines.
• Aid in the design of new spaces by optimizing room acoustics.
• Evaluate the effectiveness of acoustic treatments like panels, carpets, or curtains.

Scope and Limitations:

• The standard is intended for ordinary rooms, not specialized spaces such as concert halls or large industrial facilities (which are covered by BS EN ISO 3382-1:2009).
• It assumes that sound fields in the room are diffuse, which may not always be the case in irregularly shaped or highly absorptive spaces.

Importance:

This standard enables a consistent approach to reverberation time measurement, ensuring comparability of results across different projects and professionals. The procedures outlined are essential for achieving better acoustic conditions in a wide range of ordinary environments.

For full details, including specific methodologies, calibration procedures, and troubleshooting advice, refer to the complete text of BS EN ISO 3382-2:2008