By the end of this article, you will understand:
- Timbre and how it is managed.
- Overtones and the harmonic series.
- Enhancing emotion with overtones.
- Methods to analyze overtones.
- Overtones and Timbral manipulation in music production.
- Overtones and timbral applications in sound synthesis.
Introduction
First let’s cycle through some definitions, Frequency is the number of oscillations per second that gives a sound waveform a quality of pitch depending on the variable of oscillations per second. The faster the oscillations, the higher the pitch, the faster its velocity of motion through mediums, and the thinner its waveform. On the other hand the slower the oscillations, the lower the pitch, the longer the wavelength, the denser the waveform, and the lower the speed of motion. Therefore, when a frequency is produced due to sound pressure emission from an instrument or voice, a waveform is produced with variable of pitch, amplitude, velocity, and length. The frequency produces a fundamental tone or pitch which is prominent plus harmonically proportional overtones which are double triple quadruple etc. of the fundamental tone and less prominent yet give the sound its overall distinct character and shape depending on their harmonic/inharmonic relation to the fundamental, the intensity of the sound forms, the shape of the envelopes of the sound form, and their interactions with other sounds in the medium. That latter mentioned qualities makes what we call Timbre, the distinct character of a voice or instrument.
Natural overtones are created as a bi product to the fundamental tone when any sound is produced. All sounds produce a fundamental tone and overtones; moreover, Overtones is contributed to the quality, shape, and character of any sound depending on the intensity, envelope, and parallel interactions that makes sound distinguishable to the instrument. Like a skipping pebble (or stone) on water surface, producing a bouncing motion in proportion to its forward intensity, angle, shape, and range, so does sonic waves create proportional overtones in 2x, 3x, 4x, etc. Overall, Timbre is therefore influenced by presence, intensity, and frequency content of overtones. Moreover, it is influenced by interactions with the medium and other overtones emitted in that medium.
Simple overtones are perceived as pure. Complex overtones are perceived as warm or resonant. The way overtones shape over time shapes the timbre. The envelope compromised of the attack, decay, sustain, release has a prominent effect on the overall shape of sound. Later we will learn how a dynamic effects like like Compressors influence the shape and perception of overtones depending on methods devised. Overtones are the building block of timbre, and their manipulation allows musicians and producers to craft distinct sound and emotional texture in a song.
Harmonic series is essentially all tones, fundamental and overtones, in the range of a sound form. Depending on the tuning of the instrument, a certain harmonic ladder of pitches will be created by the act of plucking any instrument. Some tunings are more natural than others. Therefore, tuning choice has a direct influence on how overtones of an instrument are produced in relation to the fundamental pitch.
THE VARIABLES
Overall, the variables that make for the timbral quality of any sound are:
1) The strength of the overtones
2) envelope of the sound
3) Combination and interaction of overtones
4) Even or odd harmonics based on ratio of harmonic interval whether harmonic or inharmonic overtones.
The fundamental has the most audible impact in a produced sound, and it represents the true tone played on an instrument. Fundamental frequency is usually the hardest peak of any sound signal. Naturally, the frequency is more powerful in intensity on that level and less prominent in overtones from closest to furthest up the scale. The strength of the overtones can depend on the strength of the fundamental or other special qualities of the medium in a natural setting. In a post-production setting, overtones can be emphasized to be more prominent than the fundamental and have more intensity; it is arguable that some mediums can also influence how overtones may be perceived in intensity.
Envelope of sound is shaped overall by four-time intervals/movements: 1-Attack: from moment of pluck to peak, 2-Decay: from peak to consistent momentary suspension, 3-sustain: overall momentary suspension or tail before fall, and 4-Release: fade out time. In other words, Attack and decay represent the highest peak range of a sound signal from the moment it was emitted followed by sustain and release, the times which correspond with the consistent tail after the peak is reached and fade out. Depending on the nature of these time paths, the way a sound is shaped overall in perceptual character is defined. The overtones’ characters are influenced by way an instrument is played, plucked, or comes in relation to virtues applied by the natural atmosphere of the medium or artificial such as effects. Higher harmonics diminish rapidly when attack & decay are fast like staccato piano playing. By contrast, higher harmonics are more emphasized and present when notes played are sustained or the envelope is allowed to extend. Timbres generally feel crisper and more percussive when overtones fade quickly, and more expressive when sustained over fast or slow release.
The interaction of overtones of one instrument or voice with the immediate factors of the environment, other voices or instruments can emphasize and shape new qualities of timbre based on endless factors that could be applied to arrive at rich timbres. Richer or more complex tones can be created from simple or dull tones just by means of stacking or interaction with other. More on this further in the article. for now you consider it in this way: One voice has a distinct overtone while a choir’s collective overtone blend to create a richly layered timbre based on the interactions. Another example is a clean guitar that emphasizes harmonic overtones while a distorted guitar has complex inharmonic overtones, creating dense textures.
Each instrument, like each voice, produces unique overtones creating a unique spectrum of sound. While most melodic instruments properly calibrated produce harmonic overtones, drums and percussion instruments tend to produce inharmonic overtones which gives character to the sound that lends for rhythmic functions. Acoustic guitars due to their hollow nature may also produce somewhat inharmonic overtones. Harmonic overtones have the exact pitch value of the fundamental tone but in higher octaves. Inharmonic overtones have detuned values and abnormal resonant qualities. Slight detuned or phase can be caused by stacking sounds in a composition. This overlap of tones may create new perceived tones, based on their interaction. Also, effects such as saturation and distortion produced inharmonic overtones that give the sound more grit.
Enhancing emotion with overtones
Now let's add some practicality. Enhance the emotional impact of your music by manipulating the overtones. When manipulating a sound in the mixing or synthesis stage, ask yourself how am I changing and affecting the overtone range in accordance with the expression and emotion am looking for?
Enhance desired timbres: Boost frequencies of key overtones or the fundamental for clarity and emotional impact. Boosting or attenuating overtones of your sounds in a production in relation to other harmonic content in a song can yield very precise results in terms of emotional delivery and overall feeling.
Blends: Stack sounds and overlap harmonic content to blend instruments for a desired overall effect such as producing a new rich tone. Find balance between which instruments are playing which notes at a specific instance for a precise cohesive overtone expression. You can create a chain in an Ableton Live rack using 2, 3, or more instruments to play one melody or chord progression while assigning which instruments should play which notes for the given melody according to their overtone quality for the best effect. In general, be mindful by how your instruments interact from verse to chorus etc.
Create Contrast: Isolate unique overtones by ways of EQ or filtering for a unique overtone profile for each instrument that makes it distinct in the mix and features the balanced choice quality in accordance with the whole qualities. In other words, in contrast to other sounds in the composition. Giving space for each overtone for various sound to be expressed independently can have a powerful and clean impact if done with right tools and methods for precision.
So all in all you can create more clarity, more contrast, or be more creative with foundational knowledge thus far in production applications. Next, Let's look in a post production context and sound synthesis context.
TIMBRE IN MIXING
EQ Each instrument overtones’ structure blends to create a timbral palette. EQ adjusts specific frequency bands, altering overtone prominence. Therefore, manipulating the intensity of overtones by ways of cut, boost, or attenuation changes the overall timbre.
Reverb, Chorus, and Delay effects can add additional reflections to enhance overtone interactions creating rich and complex tones, thus creating a new timbre.
Distortion and saturation introduce inharmonic overtones, creating perceived gritty or biting timbres.
Compressors are used as a dynamic effect and by ways of upward or downward compression from digital compressors, or coloring from old tube or optical analog compressors, the timbral quality may shift according to the change of intensity or introduction of inharmonic overtones.
ANALYZING OVERTONES
Overtones can be analyzed visually by ways of seeing or aurally, by ways of hearing. Some of the common methods to analyze overtones are:
1) Spectrum analyzers: visually represents the frequency profiles of sounds by showing peaks, waveforms, and wavelength of the fundamental and overtone frequencies.
2) Filters: can be used on analog or digital processors to discern between the prominent, wanted, and unwanted qualities within various bands. And make decisions based on aural reads.
Overtones and timbre in sound synthesis
Sound synthesis in its various modalities and styles of application allows you to create sounds by explicitly controlling harmonic content.
A / Additive synthesis
In this type of synthesis, you start with a pure tone, a simple fundamental tone and then by means of stacking overtones on top of the fundamental, more rich tones are produced. The process goes as follows:
1) Start with a fundamental pure tone then add 2nd harmonic, 3rd harmonic
2) Control amplitude of each harmonic.
3) Adjust phase for subtle timbral shifts.
B / Subtractive synthesis
In subtractive synthesis, 2 or more oscillators produce simple or rich tones and combined they produce an even richer tone, even harsh tones that need taming of harmonic content by means of filtering. Depending on the synth, more processing can be involved to shape and enrich the timbral qualities. The process usually goes as such:
1) Choose a waveform. Sawtooth, rich harmonic or square, odd harmonic or triangle.
2) Use filter: low pass to emphasize lower and darker tones. Use high pass to emphasize thin overtones. Use bandpass for a focused harmonic range.
3) Control envelope for timbral shaping.
4) Add effects for interesting overtone interaction application and final conditioning.
C / FM synthesis
Modulate one frequency with another. A Carier wave is modulated by a modulator wave. Complex overtones and inharmonic content result can arise with dissonant or rich sonic outcome depending on the interaction of overtones and application of algorithmic effects. The process goes as such:
1) set a carrier frequency (base sound) then add a modulator frequency.
2) Adjust the operators positions and modulation depth creatively.
3) Experiment with harmonic or inharmonic ratios.
D / Granular Synthesis
Granular synthesis micro granules a played or recorded audio into tiny segments and then spreads them in time creating mirror and reflection type of phenomena that releases new artifacts and timbre.
1) Record a sample.
2) Apply granulator.
3) Control spread and rate of granulation.
4) Filter to outcome.
E / Wavetable Synthesis
Morphs two sample instances of sound and overlaps their overtones to produce rich timbral outcome.
F / Vector Synthesis
Vector synthesis operates on an XY pad where parameters may be set for variable controls. Depending on the controls set, the outcome may shift the timbral content with respect to overtone interactions, intensity, or envelope.
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