Reverberation Testing

What is reverberation?

Reverberation is a build up of sound reflecting from hard surfaces that causes it to distort.  For further information click here.

Why do we test?

To ensure that a space is suitable for its purpose. When poor acoustics within rooms or spaces are found (as a result of reverberation) adding an acoustic treatment to these areas can improve conditions and have a positive effect on all users.

Various standards and guidelines for different sectors provide target levels that must be met and include Building Bulletin 93 (BB93) primarily aimed at education.

Testing for reverberation is important as poor acoustics can have a detrimental effect on  individuals using the space. Other factors that are affected by poor reverberation:

      • Speech Intelligibility
      • Ability to listen and concentrate fully
      • Depth of Sound
How do we test?

Rooms or spaces are tested by using an Interrupted Noise method that plays a defined ‘pink noise’ covering the spectrum and frequencies associated with human hearing, through a loud speaker.  The sound level is measured as it decays (in either octave or third octave bands) and the results are then analysed to show reverberation times (including frequencies).

We use the following standards when assessing reverberation times:

ISO 3382-1:2009 Acoustics – Measurement of room acoustic parameters Part 1: Performance spaces

ISO 3382-1:2008 Acoustics – Measurement of room acoustic parameters Part 2: Reverberation time in ordinary rooms

Results

Can be shown in table or graph form and can include recommendations to achieve target reverberation levels. 

Equipment required for testing residential properties for Sound Insulation
Testing for Reverberation
Dodecahedron Speaker
Dodec Speaker
Wall treatment for reverberation
Architect specification
BB93 – An example of what is required

Whilst there are various standards and guides  for different sectors one of the most common is Building Bulletin 93 (BB93) shown in Table 6: performance standards for reverberation time which is shown below.

Type of roomTmf seconds
New buildRefurbishment
Nursery school room
Primary school: classroom, class base, general teaching area, small group room, SEN calming room
≤ 0.6≤ 0.8
Secondary school:
classroom, general teaching area, seminar
room, tutorial room, language laboratory
Study room (individual study, withdrawal,
remedial work, teacher preparation)
Science laboratory
Design and technology:
Resistant materials, CADCAM area,
Electronics/control, textiles, food, graphics,
design/resource area, ICT room, art
Music:
Primary music room
Secondary music classroom
Practice/group room, volume ≤ 30 m3
Practice/group room, volume > 30 m3
Ensemble room, Live room
Performance/recital room
Control room - for recording
Control room - not for recording
≤ 1.0
Open plan:
Teaching area
Resource/Breakout area

≤ 0.5 (see section 1,8)
≤ 1.2 (see section 1,8)

≤ 0.5 (see section 1,8)
≤ 1.2 (see section 1,8)
Music:
Primary music room
Secondary music classroom
Practice/group room, volume ≤ 30 m³
Practice/group room, volume > 30 m³
Ensemble room, Live room
Performance/recital room
Control room - for recording
Control room - not for recording

≤ 1.0
≤ 1.0
≤ 0.6
≤ 0.8
0.6 - 1.2 ¹
1.0 - 1.5
≤ 0.5
≤ 0.5

≤ 1.0
≤ 1.0
≤ 0.8
≤ 1.0
0.6 - 1.2 ¹
1.0 - 1.5
≤ 0.6
≤ 0.6
Lecture Rooms:
Small (fewer than 50 people)
Large (more than 50 people)

≤ 0.8
≤ 1.0

≤ 1.0
≤ 1.0
Teaching space intended specifically for students with special hearing or communication needs (See Section 0.4)T ≤ 0.4 averaged from 125Hz to 4kHz octave band centre frequencies and T ≤ 0.6s in every octave band in this range. ²≤ 0.4. ²
Library≤ 1.0≤ 1.2
Drama Studio≤ 1.0≤ 1.0
Atrium, foyer, entrance hall, circulation space not used for teaching and learning≤ 1.5≤ 2.0
Assembly hall, multi-purposae hall (drama, PE, audio/visual presentation, assembly, occasional music).0.8 - 1.2 ¹0.8 - 1.5 ¹
Indoor sports hall, swimming pool≤ (1.5 - 2.0)
dependant on size of space.
See section 1.6.2
≤ 2.0
Gymnasium/activity studio≤ 1.5≤ 2.0
Dance studio≤ 1.2≤ 1.5
Meeting room, interviewing/counselling room, video conference room≤ 0.8≤ 0.8
Dining Room≤ 1.0≤ 1.5
Administration and ancillary spaces
Kitchen
Office, medical room, staff room
Corridor, stairwell
Coats & locker area, changing area
Toilet

≤ 1.5
≤ 1.0
see section 1.7
≤ 1.5
≤ 1.5

≤ 2.0
≤ 1.2
see section 1.7
≤ 2.0
≤ 2.0

 Care needs to be taken when designing different areas to ensure that the space meets the requirements as listed above.

Problems with Reverberation?