This course empowers you with the knowledge and tools needed in order to hear for yourself, discern and answer the question: “Is Equal Temperament dissonant and out-of-tune?”Culturally, most of us have been exposed to only one musical tuning system. In the West, this single tuning with 12 Equally Tempered Tones has been adopted as standard, and it can be heard (with very few exceptions) in all the music around us.The majority of music consumers, and some musicians also, are unaware of the existence of other tunings like Just Intonation, the 22-ruti Hindu system, the 17-tone Arabian classic, or other temperaments having 19, 31, 43, 53, 72 and even more tones. All these, including the prevalent standard, are subject to controversial debates regarding not only consonance and beauty, but also convenience and usefulness. The “Tuning Wars”, as they have been named by historians, have been going on for centuries and to this day, the issues they brought up still aren’t settled.Many theorize and argue over the cause, unfortunately, from an opinionated perspective shaped by cultural and social conditioning and driven by the power of habit, as opposed to critical thinking, objective reasoning and personal emotional feel based on discernible acoustical facts. While opinions vary and personal preferences differ, the physical laws of sound and human acoustic perception are the same for everyone. If in the past people had limited or no access to musical resources outside 12-Tone Equal Temperament, this is no longer the case today.In this course, I present the anatomical background as well as commonly held beliefs about the human perception and interpretation of consonance and dissonance based on the latest scientific research. We study the phenomenon of beats and take their roughness as main factor of dissonance, while focusing on hearing and how to detect the beatings of overtones in simultaneous soundings of complex tones.