An electronic musical instrument comprising: a plurality of operation elements respectively corresponding to mutually different pitch data; a memory that stores a trained acoustic model obtained by performing machine learning on training musical score data including training lyric data and training pitch data, and on training singing voice data of a singer corresponding to the training musical score data, the trained acoustic model being configured to receive lyric data and pitch data and output acoustic feature data of a singing voice of the singer in response to the received lyric data and pitch data; and at least one processor, wherein the at least one processor: in accordance with a user operation on an operation element in the plurality of operation elements, inputs prescribed lyric data and pitch data corresponding to the user operation of the operation element to the trained acoustic model so as to cause the trained acoustic model to output the acoustic feature data in response to the inputted prescribed lyric data and the inputted pitch data, and digitally synthesizes and outputs inferred singing voice data that infers a singing voice of the singer on the basis of at least a portion of the acoustic feature data output by the trained acoustic model in response to the inputted prescribed lyric data and the inputted pitch data, and on the basis of instrument sound waveform data that are provided in accordance with the pitch data corresponding to the user operation of the operation element, characterized in that the acoustic feature data of the singing voice of the singer includes spectral data that models a vocal tract of the singer and sound source data that models vocal cords of the singer, and wherein the at least one processor synthesizes the inferred singing voice data that infers the singing voice of the singer on the basis of the spectral data by applying an acoustic feature of the spectral data to the instrument sound waveform data without using the sound source data of the acoustic feature data. a plurality of operation elements respectively corresponding to mutually different pitch data; a memory that stores a trained acoustic model obtained by performing machine learning on training musical score data including training lyric data and training pitch data, and on training singing voice data of a singer corresponding to the training musical score data, the trained acoustic model being configured to receive lyric data and pitch data and output acoustic feature data of a singing voice of the singer in response to the received lyric data and pitch data; and at least one processor, wherein the at least one processor: in accordance with a user operation on an operation element in the plurality of operation elements, inputs prescribed lyric data and pitch data corresponding to the user operation of the operation element to the trained acoustic model so as to cause the trained acoustic model to output the acoustic feature data in response to the inputted prescribed lyric data and the inputted pitch data, and digitally synthesizes and outputs inferred singing voice data that infers a singing voice of the singer on the basis of at least a portion of the acoustic feature data output by the trained acoustic model in response to the inputted prescribed lyric data and the inputted pitch data, and on the basis of instrument sound waveform data that are provided in accordance with the pitch data corresponding to the user operation of the operation element, characterized in that in accordance with a user operation on an operation element in the plurality of operation elements, inputs prescribed lyric data and pitch data corresponding to the user operation of the operation element to the trained acoustic model so as to cause the trained acoustic model to output the acoustic feature data in response to the inputted prescribed lyric data and the inputted pitch data, and digitally synthesizes and outputs inferred singing voice data that infers a singing voice of the singer on the basis of at least a portion of the acoustic feature data output by the trained acoustic model in response to the inputted prescribed lyric data and the inputted pitch data, and on the basis of instrument sound waveform data that are provided in accordance with the pitch data corresponding to the user operation of the operation element, characterized in that the acoustic feature data of the singing voice of the singer includes spectral data that models a vocal tract of the singer and sound source data that models vocal cords of the singer, and wherein the at least one processor synthesizes the inferred singing voice data that infers the singing voice of the singer on the basis of the spectral data by applying an acoustic feature of the spectral data to the instrument sound waveform data without using the sound source data of the acoustic feature data.