An electronic musical instrument for simulating sound of an acoustic piano, wherein the acoustic piano comprising a soundboard that is a wooden vibrating board, a plurality of strings that are a plurality of piano strings that are stretched above the soundboard and a plurality of bridges are categorized into a short bridge and a long bridge, are positioned on the soundboard, that transmit the vibrations of the strings to the soundboard, comprising: a plurality of keys including: a first key that is assigned a sound of a first pitch; a second key that is assigned a sound of a second pitch that is higher than the first pitch and being highest pitch key corresponding to the short bridge; a third key that is assigned a sound of a third pitch that is higher than the second pitch and being lowest pitch key corresponding to the long bridge; and one or more processors that acquire panning values respectively assigned to the first key, the second key, and the third key, each panning value setting forth a left-right balance between a left-channel speaker as viewed by the performer and a right-channel speaker as viewed by the performer for the sound specified by each key, and the one or more processors generating, in response to an operation of one of the first, second and third keys, corresponding sound data for outputting from the left-channel speaker and the right-channel speaker in accordance with the assigned panning value the panning values respectively assigned to the second and third keys are set such that the left-right balance of the sound data of the third key is shifted towards the left-channel speaker as compared with the left-right balance of the sound data of the second key, characterized in that the sound data of each of the first through third keys further includes hit string sound data that represents a sound produced when a string of the acoustic piano is hit in addition to the soundboard resonant sound data, and wherein a separate set of panning values is provided to set forth the left-right balance for the hit string sound data for each of the first to third keys such that the left-right balance of the hit string sound data of the second key is shifted towards the right-channel speaker as compared with the left-right balance of the hit string sound data of the first key and such that the left-right balance of the hit string sound data of the third key is shifted towards the right-channel speaker as compared with the left-right balance of the hit string sound data of the second key. a first key that is assigned a sound of a first pitch; a second key that is assigned a sound of a second pitch that is higher than the first pitch and being highest pitch key corresponding to the short bridge; a third key that is assigned a sound of a third pitch that is higher than the second pitch and being lowest pitch key corresponding to the long bridge; and one or more processors that acquire panning values respectively assigned to the first key, the second key, and the third key, each panning value setting forth a left-right balance between a left-channel speaker as viewed by the performer and a right-channel speaker as viewed by the performer for the sound specified by each key, and the one or more processors generating, in response to an operation of one of the first, second and third keys, corresponding sound data for outputting from the left-channel speaker and the right-channel speaker in accordance with the assigned panning value the panning values respectively assigned to the second and third keys are set such that the left-right balance of the sound data of the third key is shifted towards the left-channel speaker as compared with the left-right balance of the sound data of the second key, characterized in that the sound data of each of the first through third keys further includes hit string sound data that represents a sound produced when a string of the acoustic piano is hit in addition to the soundboard resonant sound data, and wherein a separate set of panning values is provided to set forth the left-right balance for the hit string sound data for each of the first to third keys such that the left-right balance of the hit string sound data of the second key is shifted towards the right-channel speaker as compared with the left-right balance of the hit string sound data of the first key and such that the left-right balance of the hit string sound data of the third key is shifted towards the right-channel speaker as compared with the left-right balance of the hit string sound data of the second key.