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architectural space / The acoustic space

The hearing mechanism Our hearing mechanism began evolving outdoors. Acoustically, outdoors means that every sound we hear is only heard once if there are no sound-reflecting objects. Hearing with two ears makes it possible to some extent to hear the direction of the sound source by correlating the signals received in two ears. To be able to do this, the wavelength of the sounds should be about the size of the head, say 5–50 cm. Sound in air has a frequency equivalent to 700 to 7000 Hz, exactly the frequency range containing the information of natural speech and the mid-range of musical sounds. It is fundamental for the behaviour of sound as a means of communicating with the world around us that the wavelengths we hear are on this kind of a human scale. Speech will be heard clearest when there is no additional reflection or reverberation. Good acoustics for speech can therefore be simply defined as sufficiently loud and with a minimum of reverberation, echo and spectral filtering. When people found shelter and started living in caves, the hearing mechanism had to cope with the fact that every sound was not heard once, but an almost infinite number of times due to the fact that sound is reflected on the walls and

ceiling. The cave’s acoustics in other words. What does our hearing mechanism do to create an impression of space? It does something that we call (binaural) deconvolution: a correlation process that recreates the original signal from a signal that is repeated many times with just as many time delays. So if we are in a reverberant space, we still can determine the sound signal that was originally sent, and also the direction from which it came (precedence effect). ‘Hearing the space’ is like receiving extra information. We get an impression of the size of a space by analyzing the reflections’ repetitive pattern, and to a certain extent even a general idea of its shape. But sound bends, diffracts and disperses due to wavelength effects; there are no straight ‘sound lines’. So there cannot be a clear acoustic picture. Music and acoustics Hearing the acoustics of a space It is not possible to hear the acoustics of a space (which is purely a physical property) as such. A signal will always be heard, often in the form of music or speech. These are complex

(Fig. 1) Simple music signal in time

(Fig. 2) The same signal, with reflections and reverberations added

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Music Space Architecture  
Music Space Architecture