Classroom acoustics checklist.

Stand in the middle of the room, clap once with flat palms and listen to how long the sound hangs in the air.

Why it matters: The WHO advises a reverberation time of about 0.6 seconds in classrooms, and the American classroom standard allows no more than 0.6 seconds in a typical classroom. (Sources: Guidelines for Community Noise, 1999; ANSI/ASA S12.60, 2010, reaffirmed 2020)

Open our free clap test on your phone in the same spot and clap three times. Note the number for each room you check. maze.education/spaces/clap-test

Why it matters: The UK's school standard asks for 0.6 seconds or less in a new primary classroom, and 0.8 seconds in a refurbished one. (Source: Building Bulletin 93 (BB93), 2015)

Sit still for a minute with the class out. Then switch on what you use in lessons and listen again.

Why it matters: The WHO advises background noise of no more than 35 decibels (dB) during teaching, so that learners can hear and understand what is said. (Source: Guidelines for Community Noise, 1999)

Listen with the windows shut, then open. Note what comes in, and the times of day it is worst.

Why it matters: In London primary schools, test results were lower where noise was higher, both noise from outside and background noise in the classroom. (Source: Noise and attainment in primary schools, 2008)

Ask a colleague to talk in a normal teaching voice next door while you listen.

Why it matters: Sound from the next room adds to the background noise learners must listen through, and the American classroom standard allows no more than 35 dBA of it in a typical classroom, averaged over an hour. (Source: ANSI/ASA S12.60, 2010, reaffirmed 2020)

Count what is soft as well: curtains, carpet, pinboards or acoustic panels.

Why it matters: A room of hard surfaces is more reverberant and sound can build up in it, and reverberation affects how well children hear speech in class. (Sources: ANSI/ASA S12.60, 2010, reaffirmed 2020; Classroom acoustics for children, 2000)

Check the door to the corridor, and any windows that face a road, the playground or a hall.

Why it matters: Noise from outside counts: in London primary schools, test results were lower where it was higher. (Source: Noise and attainment in primary schools, 2008)

Listen when the class sits down or moves into groups, and look under the chair legs.

Why it matters: In London primary schools, background noise in the classroom was linked to lower test results. (Source: Noise and attainment in primary schools, 2008)

Pace it out. Then sit in the back row while a colleague talks from the front in a normal voice.

Why it matters: Noise, reverberation and the distance between teacher and learner all affect how well children hear speech in class. (Source: Classroom acoustics for children, 2000)

Keep a tally for one lesson, and watch for learners who copy what their neighbours do.

Why it matters: Noise makes listening and understanding harder for children than for adults. (Source: Does noise affect learning? 2013)

Think of second-language learners, and children with hearing, language or attention difficulties.

Why it matters: Noise makes listening harder still for second-language learners and children with language or attention difficulties, and the WHO advises less reverberation for children with hearing loss. (Sources: Does noise affect learning? 2013; Guidelines for Community Noise, 1999)

Notice how fast the noise builds, and whether it settles after you ask for quiet.

Why it matters: In a hard, echoey room sound builds up, and noise and reverberation in classrooms were linked to poorer results in verbal tasks. (Sources: ANSI/ASA S12.60, 2010, reaffirmed 2020; Does noise affect learning? 2013)