Implications for therapists treating hearing, speech and language disorders
    Classroom acoustics are critical to proper instruction and learning. They are inadequate in
many institutions throughout the world. Due to the efforts of professionals in hearing,
speech and language as well as acousticians, planners of school buildings and politicians
in USA and Canada are now becoming aware of this problem (Siebein 2004 [15]),
whereas medical experts treating language, speech and hearing disorders appear not to
be sufficiently informed about the problem and its consequences. In many parts of the
world this issue is still not recognized. It is the intent of this presentation to focus the
interest of hearing, speech and language therapists on this issue and thus contribute
more effectively to a global improvement of the situation for teaching and learning.
    There is ample evidence that speech intelligibility is hampered in a poor acoustic
environment (Michel 2007 [12]). It is also known that the success of teaching and
learning is limited if excessive background noise or reverberation are present (Klatte et
al. 2002 [10]). But it is not well recognized that also health problems involving speech
and hearing in children may be related to or even caused by inappropriate acoustical
environments in which the children are being taught and educated (Nelson 2003 [13]). It
is reasonable to assume that a considerable number of children suspected of suffering
from central auditory processing disorders or attention deficit and hyperactivity
syndromes are merely overburdened by the demands of studying under unfavorable
acoustic conditions (and others could be simply helped by studying under favorable
acoustic conditions).
    The auditory system is the primary input channel for the acquisition of knowledge.
Understanding and processing of open speech is one of the most exiguous cognitive tasks
for the human brain. The demands are extremely difficult, but due to the high
performance of the respective brain areas, speech perception functions without any
visible effort. This holds true for nearly all areas of life, but it plays a dominant role in
teaching situations, where the exact decoding of the information transmitted acoustically
is essential for the success of learning and acquisition of knowledge. The apparent ease
of understanding produces the illusion that teaching and learning is not seriously affected
under unfavorable conditions. Therefore little attention has been paid to the acoustic
conditions of classrooms which are frequently sub optimal – with exception of special
schools for children with hearing handicaps, where extensive and expensive measures are
taken to create favorable conditions (Warncke 2000 [17]).
    Several sources of disturbing interference must be differentiated. Among them,
reverberation is one of the most important factors because it limits the quality of acoustic
transmission even in absence of external or internal sources of noise. In many
classrooms, the reverberation is comparable to that in a church or in a station hall. It is
difficult to learn differential equations or foreign languages in such an environment. But it
works, because most of the children are able to make the required effort and to predict
from context. Those who don’t possess this ability are often suspected to be affected by
one of the disorders mentioned above.
    Many solutions for the improvement of the acoustic situation in class rooms have been
described (structure of walls, floor and ceiling, technical amplification, sound fields etc.).
Some of them, e.g. the coating of walls with textile tissue (Hoth 2004 [9]), are lowpriced
and highly efficient. It is a task adopted by the IALP Audiology Committee to
convey these affordable solutions in order to contribute to a hearing-friendly world.