Abstract
With the aid of a historical review, it has been shown that the existence of a single local resonance within a broad-band acoustical or electro-acoustical system can be considered to be the unit cause for all objectively generated colourations. Such being the naturally occurring state of affairs, one is led to investigate the subjective effect of the presence of the local resonance. This was done using a single resonance colouration synthesizer with music, speech and pink noise as programme materials. The results of the subjective tests show that the degree of audibility of a single resonance colouration depends upon the type of programme material used as well as the frequency, Q and dilution of the resonance. Dilution is a parameter which gives a measure of the relative energy modification of the programme caused by the presence of the resonance. The results also indicate that subjectively generated colourations do exist, but their effect is less significant than the objectively generated variety which can be classified under the headings of: a. Driven-state colourations; b. Transient-state colourations; c. Inter-state colourations. These colourations are in turn caused by certain fundamental mechanisms like humps, transient decays and frequency shifts which govern the audibility of objectively generated colourations in general.