阮是"阮咸"，“阮咸琵琶”的简称。弹拨乐器。古琵琶的一种。现在使用的改良阮分为五种：低音阮、大阮、中阮、小阮、高音阮。四弦，有品，按十二平均律设备。定弦为：低音阮E1A1DG；大阮DAea；中阮Gdgd1；小阮da1d1a2。音域可达两组半。中阮为中音乐器，音色恬静、柔和、富有诗意，与秦琴相似，在合奏中常担任演奏旋律或描句，具有动人的效果；担任伴奏时，丰富的节奏变化更能突出乐曲的特点，在乐队中采用两个以上中阮分部演奏和声，会使弹拨乐器组的中音声部更为丰满。阮相传是魏晋名士阮咸以擅长弹奏琵琶著名，他完成了改革，所以后人称之为阮咸琵琶。

The zhongruan (Chinese:中阮; pinyin:zhōngruǎn; literally: "tenor ruan"), is a Chinese plucked string instrument. The zhongruan has a straight neck with 24 frets on the fingerboard and 4 strings. It is usually played with a plectrum (guitar pick). It can also be played with fingers (index finger and thumb with acrylic nails), which is similar to the way of playing the pipa (琵琶). The zhongruan is a tenor-ranged instrument in the family of ruan (阮). In ancient China, the ruan was called Qin pipa (Qin [Dynasty] pipa, 秦琵琶) or Ruan xian (阮咸). Now the ruan has expanded to different sizes and the zhongruan is the "medium" one.