The telephone sound effect is widely used in music, television and the film industry. This paper presents a digital model of the carbon microphone nonlinearity which can be used to produce a vintage telephone sound effect. The model is constructed based on measurements taken from a real carbon microphone. The proposed model is a modified version of the sandwich model previously used for nonlinear telephone handset modeling. Each distortion component can be modeled individually based on the desired features. The computational efficiency can be increased by lumping the spectral processing of the individual distortion components together. The model incorporates a filtered noise source to model the self-induced noise generated by the carbon microphones. The model has also an input level depended noise generator for additional sound quality degradation. The proposed model can be used in various ways in the digital modeling of the vintage telephone sound.

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This paper introduces a sound synthesis method for jackhammer tool impact sounds. The model is based on parallel waveguide models for longitudinal and transversal vibrations. The longitudinal sounds are produced using a comb filter that is tuned to match the longitudinal resonances of a steel bar. The dispersive transversal vibrations are produced using a comb filter which has a cascade of first-order allpass filters and time-varying feedback coefficient. The synthesis model is driven by an input generator unit that produces a train of Hann pulses at predetermined time-intervals. Each pulse has its amplitude modified slightly by a random process. For increased realism each impact is followed by a number of repetitive impacts with variable amplitude and time difference according to the initial pulse. The sound output of the model is realized by mixing both transversal and longitudinal signals and the effect is finalized by an equalizer.

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