Acoustics
issues, often referred to as noise problems, can be a real problem, but for
many situations the solution may be easier than you think. Here we take a look
at four commonly experienced problems in schools and how they might be
addressed.
Problem 1 - Reverberant sound levels.
Reverberant sound levels and
reflections, commonly described as echoes, are formed by sound bouncing back
off hard surfaces. We can measure the time it takes to reflect and decay by
60db and this is known as the “reverberation time”. These reflections occur due
to hard surfaces which allow much of the generated sound pressure levels to
propagate as reverberant sound. Building Bulletin [BB93] provides guidance for acceptable
reverberation times in schools.
To provide a solution we use absorptive, open cell
products such as acoustic panels which may be combined with diffusive products.
Acoustic panels can be the same colour as the surrounding decor, or they can be
covered in fabric or made into a coloured pattern and used as a design feature.
Problem 2 - Structure-borne noise transfer.
Unwanted sound can be generated
through floors and ceilings, from outside the building and from plant such as
air-conditioning within the structure, which can lead to a noisy environment in
which to work. Structure-borne noise transfer can be attributed to a lack of
insulation in walls, floors and glazing, holes in the structure, common walls,
service ducts and pipework.
By measuring the ambient
noise of a space typically over a 30minute period
a benchmark can be
established and compared to recommended levels. Readings in excess of these
ideals indicate it’s going to be a difficult space to work in.
Solutions to structure-borne
noise transfer are to use additional
insulation, increased mass, secondary walls, floating floors and resilient
fixings for plant and machinery. Pipework is one of the largest problem areas
as these are so wrapped up in the structure of the building in some extreme
cases the cheapest solution is actually to change the use of the area. Although
you can limit the problem with acoustic covers on the pipes if they are
accessible, or install an internal sound isolating room such as our Music
Practice Rooms.
Problem 3 - Problems associated with difficulties in
hearing speech in a learning environment.
Problems associated with difficulties
in hearing speech in a learning environment are not due to a lack of volume but when the words themselves are hard
to understand. Also, a linked problem is
when you hear too much, such as several conversations going on simultaneously.
It is due to sound waves bouncing all over the
place and are frequently a combination of reverberation times and/or high
ambient noise. Because the problem is a
combination of the previous two, the solutions
are going to be a combination of the previous two as well, such as acoustic
panels and acoustic curtains which can be deployed quickly to change the
characteristics of a room’s acoustics.
Problem 4 - problems with music or speech on a stage
not being heard in the auditorium.
Finally a quick look at
problems with music or speech on a stage not being heard in the auditorium. The
problem here is not down to increasing volume of the performer, you can’t just
“sing louder” or play your musical instrument louder as that would be
exhausting for the artists and ruin any kind of light and shade within a piece.
The solution is to use
panels designed to reflect the sound back into
the auditorium such as a
full sized combination of shell “towers” and overhead reflective panels being
installed at the venue. Schools or colleges with a smaller space can use ranges
designed to be folded up when not required.
