Figure 2
Cochlea section from a Hopf cochlea composed of several serially connected sections. A complex (real and imaginary part) signal from a precedent section (indexed by j − 1) enters the following section (indexed by j). Signal components that are close to the characteristic frequency \({\omega }_{ch}^{(j)}\) of the Hopf amplifier j are most strongly amplified and can be read off at this point, where the maximal amplification is determined by the Hopf parameter μ (j). Thereupon, the signal component is attenuated by a low-pass Butterworth filter, whereas sound components of lower frequencies are passed on to the next section \({\omega }_{ch}^{(j+\mathrm{1)}}\) (see text). The nonlinear nature of the amplification leads to all kinds of phenomena known from experiments on human hearing (see our Suppl. Mat. III).
