We study, in a steady state situation, the relationships that can exist between exchange (CE) and the emission of electromagnetic ion cyclotron waves resonating with energetic ring current protons. The CE process between an energetic proton and a cold hydrogen atom is considered in both its aspects: as a loss of particles and as a source of anisotropy in velocity space. This anisotropy, which is required in order that the waves be amplified, can be generated by the CE process itself because of its dependance on the proton pitch angle. By an iterative procedure we establish a formula for the wave field which includes the possible CE effect. This last effect depends in particular on the intensity of the proton source (dn/dt). One deduces from it here there exists a critical value of the source intensity (dn/dt)c which requires discriminating between three different equilibrium situations. When (dn/dt)(dn/dt)c, a strong coupling can exist between wave-particle interaction and CE, in a weak diffusion regime. In this last case one establishes a formula for the integrated wave field that only depends on three easily accessible parameters: the McIlwain parameter L, the cold plasma density n0, and the wave peak frequency fM. A preliminary study of some geos 1 data seems to indicate this effective coupling. Also we discuss, from this point of view, some aspects of the emission of the stable auroral red arcs. Finally, when (dn/df)≫(dn/dt)c, protons undergo strong diffusion, and the CE effect has negligible effect on the wave emission.