Khlui

The Khlui is a traditional Thai bamboo flute, classified as a vertical duct flute. Originating before or during the Sukhothai period (1238–1583), it remains one of Thailand’s most iconic musical instruments. The khlui is made from bamboo and is cylindrically bored, producing a distinct mellow tone. It features seven finger holes on the front and a thumb hole on the back, and it may also include a vent hole similar to that of a recorder, along with a decorative hole for attachments. Historically, a buzzing membrane was also added, similar to the Chinese dizi’s dimo, although this feature is now less common. The khlui is often adorned with decorative patterns achieved by burning the bamboo, giving it a characteristic look that matches its unique sound.

History of the Khlui

The khlui is believed to have originated before or during the Sukhothai period in Thailand, between 1238 and 1583. It was officially recognized as a Thai musical instrument during the reign of King Trailokkanat (1431–1488), who standardized traditional Thai instruments. The khlui is made from bamboo, but other materials like hardwood and plastic are also used in modern versions. Throughout the centuries, the khlui has seen modifications and adaptations to suit different musical needs and has survived in its current form through various historical developments. It is known for its versatility, capable of playing both traditional Thai music and more modern, Western-influenced pieces. The khlui’s close relative in Cambodia is the khloy, highlighting the shared cultural heritage of musical instruments in Southeast Asia.

Design and Construction

The khlui is constructed from a single piece of bamboo that is cylindrical in shape. The upper part of the flute is plugged with a piece of bamboo, leaving a slight gap that allows the player to blow air downwards. The flute has eight tone holes—seven on the front for the fingers and one on the back for the thumb. The finger holes are traditionally spaced equidistantly to produce seven nearly equal divisions of the octave, a unique tuning that characterizes the Thai sound. Additionally, the khlui once featured a buzzing membrane stretched over an additional hole near the bottom, which added a distinctive timbre to the instrument. This buzzing membrane is not commonly used today. The flute is decorated with burnt wavy crisscross patterns, which are repeated in three bands and separated by burnt lines, giving the instrument its iconic appearance.

Types of Khlui

There are three main types of khlui, each with unique features and uses in different musical contexts:

• Khlui Piang Aw: The most popular type of khlui, often made from tropical hardwood or plastic. It is a vertical duct flute with eight tone holes and is tuned an octave higher than middle C. This khlui is used for both traditional Thai songs and Western music, and it is available in B-flat or C tunings. The C khlui is modified to fit the Western chromatic scale, while the B-flat khlui is tuned to traditional Thai standards.
• Khlui Lip: The smallest of the khlui family, the khlui lip is characterized by its high pitch. It was developed to play alongside the khlui piang aw in ensembles and is often used as a leading instrument, similar to the ranat ek (xylophone) or saw duang (spike fiddle). The khlui lip is usually tuned to D, Eb, or F, with Eb being the most common.
• Khlui U: The largest of the khlui family, the khlui ū has only six finger holes and serves as the alto version of the khlui piang aw. It is tuned to E-flat, F, or G, producing a lower range compared to the other types. The khlui ū is often used in Thai bands and traditional ensembles to add depth to the musical arrangement.

Playing Technique

The khlui is played by blowing downwards into the mouthpiece, where a small gap allows air to enter the body of the flute. Similar to a recorder, the sound is produced by directing the air across a duct to strike an edge inside the instrument. The performer uses the seven finger holes on the front and the thumb hole on the back to control the pitch. Traditionally, the khlui’s tuning provides seven equal divisions of the octave, resulting in a scale that differs slightly from the Western equal temperament. This tuning gives the khlui its characteristic sound, particularly suitable for traditional Thai melodies. The khlui produces a mellow tone, making it ideal for both solo performances and as part of an ensemble.

Types of Music

The khlui is a versatile instrument used in various musical settings. It plays a prominent role in traditional Thai music, particularly in ensembles that accompany classical dance and theatrical performances. The khlui piang aw is particularly popular for playing folk melodies, while the khlui lip’s high-pitched sound makes it suitable for lead roles in ensemble pieces. The khlui ū, with its deeper tones, is often used to create harmonic depth. Beyond traditional Thai music, the khlui is also used in modern contexts, including fusion projects that blend Western and Thai music elements, which highlight the instrument’s adaptability across musical genres.