The 4th International Workshop on Signal Processing and Machine Learning SiPML 2018, The aim of the workshop is to contribute to the cross-fertilization between the research on Machine Learning (ML) methods and their application to Signal Processing (SP) to initiate collaboration between these areas. ML usually plays an important role in the transition from data storage to decision systems based on large databases of signals such as the obtained from sensor networks, internet services, or communication systems. These systems imply developing both computational solutions and novel models. Signals from real-world systems are usually complex such as speech, music, bio-medical, and multimedia, among others.