Like most people, I really love music. I listen to it all the time, and then last night, it hit me: I could right about the physics of singing for my next blog post!
To start off with some general knowledge, sound is the sensation you experience when your auditory nerves are stimulated by vibrating air molecules. A sound can be represented as a waveform. The height of the waveform represents the amplitude or loudness. The distance between two successive peaks in a waveform is called the period. The number of peaks or cycles that occur in one second is called the frequency or pitch. Frequency is often measured in hertz, kilohertz (kHz) or cycles per second (cps). The frequency of a waveform is equal to 1/periods per second. The pitch of a sound is the psychological impression of the highness or lowness of the sound. Pitch is often used synonymously with frequency; the higher the pitch, the higher the frequency.
The voice organ consists of three aspects, actuator (lungs), vibrator (vocal folds) and resonator (vocal tract) to produce sound waves in a variety of complex patterns. Each complex sound is produced by the chopping of the airstream by the vocal folds is comprised of a fundamental frequency or pitch and a large number of overtones. Every sound we make gives us an overwhelming amount of acoustical data that can be recorded and analyzed. Each musical sound possesses three distinct properties: frequency (pitch), amplitude (loudness) and timbre (tone quality or color).
If we sing a4, our vocal folds are vibrating at 440 cps, or cycle per second, or c6 at 1046.502260 cycles per second. Cycles per second can also be called the number of periods, one complete compression and rarefaction of the simple sine wave of the vocal sound produced.
Amplitude or loudness is the degree of displacement of the vibrator. It can also be defined as the magnitude of movement of a vibrating object. When we sing forte, more of the vocal folds should vibrate. When we sing falsetto, only the fringes of the vocal folds vibrate. Loudness is measured in decibels. A sound of a jet plane taking off is usually around 120 DB, and a soprano singing C6 at 1046 cps is around 100-105 DB. A Bruckner symphony ranges from around 90DB in a fortissimo passage to a 40-50 DB range for pianissimo
So there you go, those are the basics of the physics of singing!