Harmonics and equal loudness contour - a consideration of sound design

On an acoustic instrument, the thinking of loudness is more than just the volume in dB. When a note is played on an acoustic instrument, a series of overtones is also produced. The fundamental and overtones above also contribute to the loudness. When playing in louder volume compared to softer, the loudness in decibel of the fundamental does not have a big difference, but the overtone pattern has an obvious increase. Example below.


Using a reversed example to explain the same phenomenon, this is a pure data patch (Example below). It is playing with the same amplitude or decibel. With adding more harmonics to it, the volume sounds louder to our ears.

In terms of sound design, using fewer harmonics on a synthesizer results in a mellow softer tone; on the contrary, harsher and buzzier tone.

Why it is louder with more harmonics, the short answer is more people (harmonics) playing at the same time - louder. But if you notice the natural decay of the harmonic series, this is part of the answer. Our ears have a different sensibility of various bands of frequency. According to the chart below, 4kHz is the most sensitive band. We need less volume to feel the same "loudness" as other band frequencies. Back the flute sample, in forte, the richer overtones cover more the bands of our sensitive frequencies around 4kHz, when I only played A4=440Hz.

Isophone
An equal loudness contour graph

Comments

Post a Comment

Popular posts from this blog

Post-spectralism influence on tuning

According to Helmholtz (2011), a musical note is due to the fundamental frequency and the quality of a musical sound is due to the presence of upper partials. For traditional western music, pitch perception is mainly fundamental, rather than the frequencies in the spectrum which Teodorescu-Ciocanea (2003) describes as a “note proper” tradition. The spectralism composers shifted the domain from absolute pitches, intervals and chords to the spectrum. Spectral music is a complex approach to timbre, Teodorescu-Ciocanea (2003) classified 9 tendencies and their possibilities in spectral music. To conclude the techniques, tuning the frequencies according to the harmonic series is the major approach; while working with noise, generated digitally and/or extended techniques on instruments, is a sort of timbral dissonance which dilutes the pitch perception of a musical sound. Teodorescu-Ciocanea describes inharmonicity as the combination of frequencies that are not integral multiples of the funda
Read more

Haba's field shifting - and the expansion of traditional functional harmony

Image
Hába characterizes the quarter-tone gamut as separated into two fields, one half comprising the twelve conventional pitches, and the other half, shifting all the twelve notes by a quarter-tone, the twelve quarter-tone pitches. In harmony, Passages occur in which chords composed purely of conventional pitches alternate with chords composed purely of quarter-tone pitches. Two fields are not always rejecting each other when he equally divided a perfect 4th (5 semitones)into 2 equal intervals, equal 2.5 for each, the 0.5 quartertones always step into the other field. Sometimes, this fourth interval can be further divided into 2.5+2+0.5 or other permutations. This kind of splitting a fourth can be traced to ancient greek tetrachord, a scale of four notes, bounded by the interval of a perfect fourth. A chord across both fields, the chord spell like a flatter dominant 7th chord. the 7th harmonic on harmonic series is quite flat (-31cents). This chord combines both fields sounds better accordi
Read more

Temperament, Tuning, and Timbre -- the underrated trinity in music

 The trinity here is not about the Christianity faith, but similar to the idea of the Christian doctrine of it defines God as being one God existing in three coequal, the core and fundamental definition, temperament, tuning, and timbre (TTT) are the basic building blocks of music, yet, underrated and even neglected in our music education system. TTT correlates with each other. A note is played, it carries out a series of frequencies, the harmonic series. The series multiples from the fundamental frequency with a series of integers (1f 2f 3f 4f 5f 6f 7f 8f 9f 10f 11f 12f 13f...). The loudness of individual particles, and different patterns, creates different timbres. View the series in a different way, the combination of the integers creates intervals. The combination of the beginning of the series sounds more harmonious and vice versa; simple ratios sound pure and vice versa. The pure perfect 5th interval is based on the ratio of 2:3 (2nd and 3rd harmonics at the same time), Pytheogoro
Read more