Is Pitch Related to Frequency? A Simple Guide to Sound and Music

Sound is a form of energy that travels through a medium, such as air or water, as a wave. A sound wave consists of alternating regions of high and low pressure, called compressions and rarefactions, that propagate through the medium. The characteristics of a sound wave, such as its frequency, amplitude, and speed, determine how we perceive it as a sound.

What is Frequency?

Frequency is the number of times a sound wave oscillates per second, measured in hertz (Hz). One hertz means one cycle per second, so a sound wave with a frequency of 100 Hz oscillates 100 times per second. Frequency is related to the wavelength of a sound wave, which is the distance between two consecutive compressions or rarefactions. The higher the frequency, the shorter the wavelength, and vice versa.

What is Pitch?

Pitch is how high or low a sound sounds to us, based on our perception of its frequency. Pitch is not a physical property of a sound wave, but a subjective sensation that depends on various factors, such as the context, the listener’s hearing ability, and the musical culture. For example, a sound with a frequency of 440 Hz may sound different to different people, depending on whether they are used to Western or Eastern music scales.

Frequency and pitch are not equivalent, but they are correlated. This means that as one goes up, the other does as well. A higher frequency produces a higher pitch, and a lower frequency produces a lower pitch. However, the relationship between frequency and pitch is not linear, but logarithmic. This means that as the frequency increases, the pitch increases more rapidly at first, but then more slowly later on. For example, doubling the frequency of a sound wave increases its pitch by one octave, which is the interval between two notes that have the same musical quality. An octave is divided into 12 semitones in Western music, each corresponding to a fixed ratio of frequencies. For example, the note A4 has a frequency of 440 Hz, and the note A5 has a frequency of 880 Hz. The ratio between these two frequencies is 2:1, which means they are separated by an octave. The note B4 has a frequency of about 494 Hz, and the ratio between A4 and B4 is about 1.12:1, which means they are separated by one semitone.

Why is Frequency and Pitch Important for Music?

Frequency and pitch are important for music because they determine the melody and harmony of a musical piece. Melody is the sequence of pitches that form the main tune of a song, while harmony is the combination of pitches that create chords and support the melody. Different musical instruments produce different frequencies and pitches by varying their length, tension, or shape. For example, a guitar string produces a higher pitch when it is shorter or tighter, while a flute produces a higher pitch when it has fewer holes open. By manipulating these factors, musicians can create different notes and play different songs.

According to How Music Works, every musical note is associated with a unique frequency. The two widgets below allow you to investigate the relationship between a musical note and the associated frequency.

Conclusion

Frequency and pitch are two concepts that describe different aspects of sound and music. Frequency is the physical measure of how fast a sound wave oscillates per second, while pitch is the perceptual measure of how high or low a sound sounds to us. Frequency and pitch are correlated, but not equivalent. A higher frequency produces a higher pitch, and vice versa. However, the relationship between frequency and pitch is not linear, but logarithmic. Frequency and pitch are important for music because they determine the melody and harmony of a musical piece. Different musical instruments produce different frequencies and pitches by varying their length, tension, or shape.