A New Experience of Music Creation for Plebeian: Musical Accompaniment Apps on Smartphone

長久以來音樂於人們生活中扮演著極為重要角色，在大多數人的成長過程裡或多或少皆有令其印象深刻之旋律。然而這些旋律常由專業人士所創作，對於未接受過專業訓練的民眾而言，若欲創作自己專屬之音樂難度甚高，而此目標也變得遙不可及。 為解決上述問題，降低音樂自行創作門檻，本研究以行動裝置之使用環境不受限及直覺性觸控介面兩大特性為運行環境，設計Android系統上之音樂創作軟體，協助未受過音樂專業訓練的庶民透過音樂主旋律並搭配適合的和弦配樂達成自行創作音樂之目標。本創作音樂軟體利用行動裝置提供「繪畫旋律曲線」與「字詞輸入」兩種輸入方式，將使用者繪畫的旋律曲線轉換為一段音樂主旋律，進行調性判斷、修正主旋律組成音並利用音樂動機樣式變化加以使主旋律更為豐富，輔以隱藏式馬可夫模型產生適切之和弦序列。最後將主旋律聲波與其產生的和弦聲波以混音的結果呈現給予使用者。 為評估本創作軟體是否符合使用者需求，以實驗觀察法邀請38位受試者進行軟體操作與評估。分析結果顯示，近75%的受試者認為由音樂創作軟體所產生之主旋律與和弦彼此搭配良好且符合其音樂動機。在介面易用性評估方面，結果顯示有近90%受測者認為本研究所提出的音樂創作軟體具有簡單易用之特性且能夠協助其降低創作音樂之門檻。簡單且易用的音樂創作軟體在實務上之重要性不言可喻，不但可使非專業使用者達成自我創作音樂之夢想，更可讓其沉浸於音樂創作成就感之中。Music plays as an essential role in human life and it affects the listeners on a certain extent. However, a pleasing music is the production of musicians and is difficult to be created by novices without musical specialty. To lower the entry point of music creation, this thesis design and develop a music accompaniment system on Android with the characteristics of intuitive input and ubiquity for novices without professional music background. The developed system consists of the following modules, main melody preprocessing (key determination and melody modification), music similarity retrieval, main melody post processing (music motif variance), chord accompaniment (Hidden Markov Model and mixing main melody and chord melody) and text processing (tone determination and pitch finding) to automatically match the accordance between melodies and chords that are inputted by patting or word. Thirty-eight participants were invited for system evaluation using the observational experiment. Nearly 75% of participants perceived that the melody and chord matching fits their musical motivations, while 90% stated that they can rely on the system to easily produce desirable music. Our findings contribute to the essence of music creation that the system provides a simplified interface for novice being immersed in music accomplishments, similar to that of professional musicians