Courses:PHYS341/2021/Project1
Introduction
A guitar pick is a small device commonly used to pluck the guitar with (1). Originally, feather quills were used commonly as guitar picks until tortoiseshell became the main material in the 19th century (1). After it became illegal to manufacture guitar picks using tortoiseshells in 1973, celluloid became the most popular material to make picks, even today (1). Picks became more commonly used amongst guitar players partly due to the fact that picks are able to produce a larger volume compared to when playing bare-handed (1). Nowadays, there are a wide variety of guitar picks that differ in these five aspects: thickness, hardness, texture, size/shape, and material (2). All of these factors can make an impact on the tone and timbre of the guitar.
Pick Material and Thickness
Material
The following are 4 common types of pick materials:
- Nylon: a type of plastic that is extremely flexible (3)
- Celluloid: a type of plastic that is stiffer than nylon but relatively flexible compared to other materials (i.e. metal) (3)
- Delrin: a type of plastic that is relatively stiff (3)
- Stone: extremely stiff material (3)
Different pick materials will have their own properties. Density and flexibility can affect the playability of the pick and the interaction between the string and the pick (4). The hardness of the material describes the scratch-resistance property and tendency of the material to wear over time(4). Hardness can also describe the stiffness of a pick (2). The texture of the material can affect what harmonics are excited (8). A pick with a rough texture may excite more harmonics while a pick with a smooth texture would glide smoothly across the string, exciting less harmonics (8).
Thickness
The following are 3 pick thickness classifications:
- Thin picks: less than 0.60 mm in thickness (3)
- Extremely flexible, with nylon being the most flexible out of the different materials
- Medium picks: between 0.60 and 0.80 mm in thickness (3)
- Stiffer than thin picks
- Thick picks: more than 0.8. mm in thickness (3)
- Extremely stiff
Thickness of the guitar picks has one of the most noticeable effects on playability and tone (4). Thin picks are generally more flexible than thick picks, and the volume that can be produced is limited by the higher flexibility (2). Due to this reason, thin picks are better for strumming because they have slightly less control compared to thick picks (2). Thick picks aren’t as flexible, so the player has better control over the pick and the volume (2). Guitar solos are often played using thick picks because of the speed and accuracy that it provides with the greater stiffness (2). Generally speaking, stiffness of the pick increases with pick thickness (3).
Pick Material and Thickness on Guitar Tone
Usually, thin picks create lighter tones with higher frequencies while thick picks create heavier tones with low to midrange frequencies (3). Some say that thin picks produce mellower tones because the higher flexibility limits control over volume (3), while others say that thick picks produce mellower tones because of the emphasis on low frequencies. Also, there can be varying stiffness between picks with the same thickness due to the characteristics of the materials (i.e. 0.60 mm metal pick versus nylon pick) (2).
Fourier’s theory states that any time graph with a frequency f can be reproduced by adding sinusoidal time graphs with frequencies f, 2f, 3f,… with different amplitudes (6). By looking at the spectrum graphs of guitar strings played by different materials, we can see more clearly how their properties can affect the tone of the guitar. Figures 1 to 4 are the spectrum graphs of the low E string being plucked with four different materials: thumb, nylon, celluloid, and coin.
The celluloid and nylon picks are similar in thickness (0.53 mm), with the nylon pick more flexible than the celluloid pick. The thumb is very soft, and the coin (1.95 mm) is extremely stiff. As you can see, figure 2 and figure 3 have the widest range of frequencies present (between 60 to 4000 Hz), followed by figure 4 and figure 1 (between 70 to 3000 Hz). Figure 1 and figure 4 show greater emphasis on lower range frequencies (higher peaks in the mid to low range of frequencies), and figure 2 and figure 3 show greater emphasis on higher range frequencies (presence of higher harmonics and higher peaks for the high frequency range). If we compare stiffness by looking at the nylon and celluloid picks with similar thickness (figure 2-3), it looks like they have similar frequencies present, but the celluloid pick that is stiffer has greater amounts of higher frequencies. Then, if we compare thickness by looking at celluloid pick and the coin (figure 3-4), the thicker coin emphasized much more heavily on mid-range frequencies. These observations support the common perception that thin picks produce brighter tones as high-frequency harmonics can cause a sound to be perceived as bright (5). They also support the perception that thicker picks bring out more bass tones with greater amplitudes of lower harmonics. Regarding the effects of stiffness, it looks like the material and the thickness of the pick interact to bring about different effects. The celluloid pick is thin and stiff, and the coin is thick and stiff. The coin excited lower harmonics more while the celluloid pick excited greater amounts of higher harmonics. In addition, texture could be the main reason for the thumb to excite the least harmonics compared to the other materials.
Besides the differences in spectrum graphs, we can also see differences in the time graphs (Figure 5). The principle of Superposition states that the displacement of a medium is the sum of displacements of individual waves traveling on the same medium undisturbed (7). The pick materials in figure 5 are as follow from top to bottom: thumb, nylon, celluloid, and coin. The time graph from the thumb pluck is the smoothest of the four, and the spectrum graph (figure 1) confirms that the string had the smallest range of harmonics compared to the other three (figure 2-4). The nylon and celluloid picks have the most complicated time graphs of the four, with their spectrum graphs showing the greatest range of harmonics excited by the pick (figure 2-3).
References
(1) https://www.premierguitar.com/articles/25204-the-surprisingly-long-history-of-the-guitar-pick?page=2
(2) https://ehomerecordingstudio.com/best-guitar-picks/
(3) https://guitargearfinder.com/guides/ultimate-guide-to-guitar-picks-materials-thicknesses-faq/
(4) http://hubguitar.com/recommended-products/complete-guide-to-guitar-picks
(5) http://musicweb.ucsd.edu/~trsmyth/pitch175/Pitch_Brightness.html#:~:text=High%2Dfrequency%20partials%20make%20a,brighter%20than%20a%20low%20pitch.
(6) https://scholar.harvard.edu/files/david-morin/files/waves_fourier.pdf
(7) https://isaacphysics.org/concepts/cp_superposition
(8) https://music.stackexchange.com/questions/44840/why-do-thicker-guitar-picks-result-in-a-darker-tone-color