Samuel Sanassee Unit 35: Sound Creation and Manipulation
Task 1 - The Basics of Synthesis
The Relationships between Frequency, Wavelength and Amplitude
Waves are the base of sound, without wavelengths and frequencies we would have nothing but silence.
A wavelength is the distance between identical points on consecutive waves. In the youtube video listed in the bibliography, MattRynolds96 explains sine waves in depth and how to relate amplitude, wavelength and distance together.
Frequency is the number of waves that pass a certain point per unit time.
Amplitude is the highest/lowest point of the wave (also known as crest and trough).
In music a wavelength determines how high or low a frequency is. The shorter the wavelengths the higher the pitch (frequency) therefore the sound would decay faster. The amplitude of a wave in musical terms would be the volume (loudness) of a sound. The frequency of any wave is measured in Hz, 1 Hz is one wave cycle per second.
λ = wavelength
f = frequency
v = velocity
The velocity of a wave is measured by v=λf. By rearranging this formula you could work out the frequency (f=v/λ) or wavelength (λ = v/f).
The Basics of the Main Waveforms
There are different types of waveforms that generate different sounds such as: Sine waves, saw waves, square waves and triangle waves. Each waveform has a way of showing that they have harmonics/overtones; they are normally even and/or odd multiples of the fundamental frequency, 110Hz. All four of these waves are a representation of waveform amplitude (a visual description of how the amplitude in each waveform oscillates).
This is a site in which I found more information on acoustic theory and waveforms:
https://public.wsu.edu/~jkrug/MUS364/audio/Waveforms.htm
Sine waves:
Is a curve representing oscillations of constant amplitude. Sine waves don't have overtones (harmonics) because they only use the fundamental tone to produce sound. The sound of a sine wave is often smooth.
Saw waves (also known as sawtooth wave):
They are waves which can be created by adding extra harmonics (sine waves) via additive synthesis. The more sine waves added to a sawtooth wave the more the wave looks like a sawtooth and the longer it'll take for the amplitude to reach its peak point. Sawtooth waves have even and odd harmonics which allows it to sound full and rich.
saw wave example mp3
Square Waves:
Like triangle waves, square waves have only odd harmonics (110Hz, 330Hz, 550Hz etc..) but in larger quantities relative to the fundamental frequency. The more odd multiples of the fundamental that is added to a square wave (its initial sine wave) the more the wave would resemble a square wave. Square waves have sudden peaks and sudden drops in amplitude which gives it its grittiness.
square wave example mp3
Triangle waves:
Triangle waves contain odd harmonics and overtones multiples to the fundamental frequency. Just like a sawtooth wave, the triangle wave takes more time to reach its peak amplitude however it doesn't have the sudden drop of amplitude that the sawtooth wave does. Therefore it takes more time for the triangle wave to reach its crest and trough.
Triangle wave example mp3
I.e 2+-4 = -2
Sine waves are best used for stringed instruments such as bass and guitar. The body of a guitar like the hollowness of an acoustic guitar produces the overtones and harmonics due to the waves being reflected within the guitar. The same would apply to to an electric stringed instrument such as the bass or electric guitar; guitar pick ups just replicate what an acoustic guitar does but allows the guitarist to manipulate the guitar sound.
Square waves are best formed from some wind type instruments such as the saxophone and trombone. The amplitude at the crest and trough are constant; this gives it, its square shape. Square waves are used in synthesisers to make the sound more 'punchy'.
Triangle waves are produced by woodwind instruments such as the flute, tin whistle and recorder. This is because all these instruments have a equal but constant increase/decrease in amplitude thus creating a triangle wave.
Sawtooth waves are created by percussion instruments like a drum kit; a sudden increase in amplitude to then a constant decrease in amplitude gives it the sawtooth shape. A symbol hit lightly gives starts of quietly and gradually increases. A symbol could also be hit with a lot of force therefore letting the symbol ring out and creating a gradual decrease in amplitude.
In these synthesised patches, I have only used one oscillator to demonstrate an audible example of what each wave form does to a sound:
There are different types of waveforms that generate different sounds such as: Sine waves, saw waves, square waves and triangle waves. Each waveform has a way of showing that they have harmonics/overtones; they are normally even and/or odd multiples of the fundamental frequency, 110Hz. All four of these waves are a representation of waveform amplitude (a visual description of how the amplitude in each waveform oscillates).
This is a site in which I found more information on acoustic theory and waveforms:
https://public.wsu.edu/~jkrug/MUS364/audio/Waveforms.htm
Sine waves:
Is a curve representing oscillations of constant amplitude. Sine waves don't have overtones (harmonics) because they only use the fundamental tone to produce sound. The sound of a sine wave is often smooth.
Saw waves (also known as sawtooth wave):
They are waves which can be created by adding extra harmonics (sine waves) via additive synthesis. The more sine waves added to a sawtooth wave the more the wave looks like a sawtooth and the longer it'll take for the amplitude to reach its peak point. Sawtooth waves have even and odd harmonics which allows it to sound full and rich.
saw wave example mp3
Square Waves:
Like triangle waves, square waves have only odd harmonics (110Hz, 330Hz, 550Hz etc..) but in larger quantities relative to the fundamental frequency. The more odd multiples of the fundamental that is added to a square wave (its initial sine wave) the more the wave would resemble a square wave. Square waves have sudden peaks and sudden drops in amplitude which gives it its grittiness.
square wave example mp3
Triangle waves:
Triangle waves contain odd harmonics and overtones multiples to the fundamental frequency. Just like a sawtooth wave, the triangle wave takes more time to reach its peak amplitude however it doesn't have the sudden drop of amplitude that the sawtooth wave does. Therefore it takes more time for the triangle wave to reach its crest and trough.
Triangle wave example mp3
Instruments and their waveforms
A single string plucked on a guitar would be its fundamental tone plus the multiples of the fundamental (harmonics) and some extra noises (overtones). On a guitar, each string has its fundamental frequency as well as harmonics and overtones; the frequency of a chord (more than 3 notes played at once) would be the sum of frequencies emitting from each string that is plucked.
Some frequencies cancel out each other out and some can be added to each other. Which is why some frequencies have waves in which one cycle of sine wave could have a bigger amplitude than the next.
If the amplitude of one frequency is below 0 and is added to a frequency with an amplitude higher than 0 then the amplitude of summed up frequency would be the sum of the two numbers. Some frequencies cancel out each other out and some can be added to each other. Which is why some frequencies have waves in which one cycle of sine wave could have a bigger amplitude than the next.
I.e 2+-4 = -2
Sine waves are best used for stringed instruments such as bass and guitar. The body of a guitar like the hollowness of an acoustic guitar produces the overtones and harmonics due to the waves being reflected within the guitar. The same would apply to to an electric stringed instrument such as the bass or electric guitar; guitar pick ups just replicate what an acoustic guitar does but allows the guitarist to manipulate the guitar sound.
Square waves are best formed from some wind type instruments such as the saxophone and trombone. The amplitude at the crest and trough are constant; this gives it, its square shape. Square waves are used in synthesisers to make the sound more 'punchy'.
Triangle waves are produced by woodwind instruments such as the flute, tin whistle and recorder. This is because all these instruments have a equal but constant increase/decrease in amplitude thus creating a triangle wave.
Sawtooth waves are created by percussion instruments like a drum kit; a sudden increase in amplitude to then a constant decrease in amplitude gives it the sawtooth shape. A symbol hit lightly gives starts of quietly and gradually increases. A symbol could also be hit with a lot of force therefore letting the symbol ring out and creating a gradual decrease in amplitude.
In these synthesised patches, I have only used one oscillator to demonstrate an audible example of what each wave form does to a sound:
- Saw wave - the sound comes in straight away and slowly decays.
- Square wave - compared to the saw wave it is punchier and has more 'grit' to the sound.
- Triangle wave - Is the softest out of the three waves and doesn't naturally have a lot of drive unlike the sawtooth wave and the square waves which have sudden increases of amplitude.
Logic Synthesisers and their Limitations
Logic Pro from apple comes with pre-installed synthesisers. However their are a lot of limitations to these software instruments.
The ES1 is one of logics most basic additive synthesisers. The ES1 has 2 oscillators which allows the user to be able to mix two different wave forms together to make a new sound. This synthesiser, being logic's most basic, has only 1 filter containing: a filter cut off, drive, resonance and key change. The filter cut off allows the user to create a low or high pass filter (LP/HP) which is pretty limited when compared to its son the ES2. Drive allows the user to increase the level of force and loudness a note would make when pressed. Resonance gives the user the ability to change the rate of the vibrations a sound produces. The 'Key' option can help further manipulate the sound by changing its key to an octave above or below.
The ES1 has one LFO (low frequency oscillator) which means a user could pick the wave form of the low end frequencies that we cannot hear and puts it to use to make the sound more rich and full. A user can change the rate of the LFO up to 24.5Hz. As far as a modulation matrix goes, the ES1 is limited to 8 paths/sources: Pitch, Pulse Width, Mix, Cutoff, Resonance, Volume, Filter FM and LFO Amp. Next to the router/matrix there is a modulation envelope which controls the attack and decay of the modulation matrix (router). The ES1 only has 1 envelope which would be the ADSR (Attack, Decay, Sustain and Release.
In comparison to the ES2 this synthesiser is pretty easy to work with however it is limited to a lot of things. Which doesn't make it much of a creative software instrument. As an external alternative to the logic synthesiser, the Steinberg Retrologue 2 has a lot more to offer.
The Steinberg Retrologue 2 has a lot more features than the ES1 and was designed for quick editing.
The retrologue 2 has 3 oscillators in which you could mix and combine 3 different waveforms together to create a truly unique sound. There is a dedicated column for the oscillation mix which would control the levels of the 3 different wave types. The filter tab contains: envelope, key follow, filter cutoff, distortion as well as its own ADSR and extra option for velocity. This filter already has more options than the ES1 which allows creativity and more manipulation techniques.
The modulation matrix isn't as limited as the ES1, there are options for 4 paths and 4 sources to be used at once. Whereas the ES1 allows only 1 source and 1 path. The 'modulators' tab allows you to change the wave type, phase and frequency of all 4 LFOs and the 5th envelope.
The retrologue 2 contains an amplifier in which you can pan the sound change the drive/level. The amplifier, just like the ES1 has its envelope which allows for more manipulation. The amp envelope also has a velocity option which the ES1 doesn't have.
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