Naada Reeds

Reed instruments are a family of musical instruments that produce sound through the vibration of a reed, a thin strip of material (typically wood or synthetic material) that is attached to a mouthpiece. When the reed is vibrated by the player’s breath, it creates sound waves. Naada Reeds is a collection of inspired reed instruments from various cultures around the world. The instruments included are:

  • Clarinet (Soprano and Bass).
  • Saxophone (Tenor and Baritone).
  • Naadaswaram.
  • Shehnai.
  • Duduk (Two double-reed variants and one with a clarinet reed).
  • Guan.
  • Suona.

Articulations and Playing options

Flutter, Fall, and vibrato are supported. MIDI expression and breath messages can be used to control reed pressure, enhancing realism. A higher velocity accompanying a MIDI note-on message results in a stronger attack.

Samples

H. Mancini, Pink Panther, Naada Reeds (Tenor Saxophone), Naada PluckedStrings (Acoustic Bass)

Physics

The physics of a reed instrument can be divided into three key components: the properties of the reed, the bore and its tone holes, and the interaction between the reed and the bore. Mouth pressure is the primary physical parameter that the player modulates to achieve expressiveness.

Bore: The bore is represented as a Digital Waveguide, where the propagation of the pressure wave is modeled as the sum of waves traveling in opposite directions (see Figure 1). The interface between the bore and the air is modeled as a digital filter, that transmits a portion of the incoming wave to the air, resulting in sound emission. Instruments such as the clarinet, which feature a cylindrical bore, produce sound with almost no even harmonics as the reed end of the bore can be considered to be closed. In contrast, conical bore instruments like the Saxophone are capable of producing all harmonics. The waveguide model can be adapted for a conical bore by incorporating a “shunt” at the beginning of the cylindrical bore. This approach was first introduced by Arthur Benade [2].

Figure 1: A schematic illustrating the waveguide representation of the pressure wave within a cylindrical bore.

Reed: A reed is a thin, flat piece of material that vibrates when air is blown across it, generating sound. The vibration of the reed’s tip against the mouthpiece produces oscillations that closely match the bore’s natural frequency, forming the foundation of the instrument’s tone. In woodwind instruments, the reed is typically modeled as a massless spring. As a result, its displacement can be treated as occurring instantaneously in response to the applied force. Additionally, the reed’s natural frequency, which is typically above 5 kHz, is sufficiently high that it can be neglected in the modeling process. Spontaneous oscillations can be sustained only when the air flow into the bore decreases as the pressure difference across it increases. Figure 1 illustrates the relationship between air flow and pressure difference.

Figure 2: Air flow through the Naada Reeds Clarinet reed as a function of the pressure differential across it. Following the attack phase, the reed operates in the region of the graph where the slope becomes negative, indicating negative input impedance. The air flow graph for a double reed is steeper exhibiting hysteresis in the operating region making the sound brighter [1].

Reed-Bore Interaction: A key question is, “How does the airflow into the bore affect the pressure wave?” Answering this will help determine the value of P given P+ and the mouth cavity pressure on the opposite side of the reed (see Figure 2). This can be computed using the following information:

  • The flow and pressure are continuous at the the reed-bore boundary.
  • The airflow into the bore is governed by Bernoulli’s equation.
  • The relationship between flow and the pressure difference across the reed follows a graph similar to that shown in Figure 2.

References

  • [1] “Experimental Research on Double Reed Physical Properties“, André Almeida, Christophe Vergez, René Caussé, Xavier Rodet, SMAC 2003.
  • [2] “Equivalent Circuits for Conical Waveguides“, Arthur Benade, J. Acoustic Soc. Am. 1988.