IRYW - Tone : you think you do, but you don’t

Ah, tone. That mystical quality that makes guitarists spend thousands on vintage gear and argue endlessly on forums about whether brass or steel bridge pins make a difference. We all know what good tone is, right?

Well... maybe not as much as we think.

The Golden Ear Myth

Let's start with a controversial statement: Most of us can't actually hear what we think we can hear. You know that guy who swears he can tell the difference between a 1959 Les Paul and a 1960 just by listening? He's probably wrong.

But before you grab your pitchforks, let me explain why this isn't an insult - it's just how our brains work.

The Science of Sound (and Self-Deception)

Here's what actually happens when we evaluate tone:

1. Our ears receive sound waves

2. Our brain processes these waves through the auditory cortex

3. Our expectations, biases, and previous experiences color our perception

4. Higher cognitive processes in the prefrontal cortex integrate this information with our memories and expectations

5. We form an opinion that we think is purely about sound, but isn't

The tricky part? Most of this happens without us realizing it. The scientific term for this is "expectation bias," and it's been extensively documented in music perception studies. A famous 2012 study by Claudia Fritz1 had professional violinists try to distinguish between Stradivari violins and modern instruments. Not only could they not reliably tell the difference - many preferred the modern instruments when playing blind.

This isn't unique to string instruments. A 2010 study in the Journal of Wine Economics2 found that even expert wine tasters were significantly influenced by price tags and labels - similar to how guitarists react to brand names and vintage years. Our brains quite literally process the same sensory input differently based on our expectations.

The Wood Doesn't Lie (But We Do)

Let's talk about tonewood - everyone's favorite argument starter. Recent scientific research tells us something fascinating about wood properties that most tone-obsessed guitarists completely ignore.

The Species Myth: When Averages Lie

Before we dive into moisture content, let's tackle a fundamental misunderstanding about tonewood species. Guitar forums love to debate whether maple sounds "brighter" than mahogany, or if Indian rosewood has more "bottom end" than East Indian rosewood. But these discussions ignore a crucial statistical reality: the variation within species is often greater than the average difference between species.

Think about human height. Yes, Dutch people are on average taller than Italian people, but if you picked a random Dutch person and a random Italian person, would you bet your life savings on the Dutch person being taller? Of course not - because the variation within each population is much larger than the average difference between them.

The same principle applies to wood. Research shows that factors like:

• Density variation (which can vary by 20% within the same species)

• Growth ring spacing (which affects stiffness and damping)

• Grain orientation and regularity

• Cellular structure variations

Can create bigger differences between two pieces of the same species than the average difference between two different species. A study by Brémaud3 found that the coefficient of variation for mechanical properties within species could be as high as 30%, while the average differences between similar species were often less than 10%.

So when someone tells you "maple sounds brighter than mahogany," they're making the same kind of oversimplification as saying "Dutch people are tall" - it might be true on average, but it's nearly meaningless when looking at individual samples.

The Moisture Factor

A comprehensive 2018 study published in Acta Physica Polonica A4 revealed that moisture content in wood has a dramatic impact on tone - far more than many of the subtle differences we obsess about. The research found that:

• Wood moisture content directly affects the damping properties (how the wood absorbs and transmits vibration)

• Even small changes in relative humidity can significantly alter these properties

• The effect is particularly pronounced in spruce, one of the most common tonewoods

• Professional instrument makers dry their soundboards to approximately 6% wood moisture for optimal performance

For perspective: the difference in damping properties between properly and improperly moisturized wood is often greater than the difference between various species of tonewood that guitarists endlessly debate.

Age Isn't Just a Number

The same study found fascinating differences between new and old wood:

• Old spruce (130+ years) showed more uniform moisture release patterns

• New wood was more unstable in its moisture retention

• Older wood generally demonstrated lower damping, which translates to longer sustain and potentially more complex harmonics

But here's the kicker: while professional luthiers carefully control wood moisture and understand these aging processes, most guitarists are too busy arguing about whether Madagascar or Indian rosewood sounds "warmer" - a distinction that's often smaller than the impact of a 5% change in wood moisture content.

The Marketing Machine vs. Reality

This statistical reality creates an awkward situation for guitar manufacturers. It's much easier to market "premium Honduran mahogany" than to explain "we carefully select wood samples based on their individual mechanical properties regardless of species." This leads to marketing-driven myths that ignore the complex reality of wood properties.

Consider this: Two pieces of maple from the same tree can have more different tonal properties than maple and mahogany from different continents. Studies of wood mechanics show:

• Density can vary by up to 30% within a single tree

• Elastic modulus (stiffness) can vary by 25% or more

• Damping properties can differ by up to 40%

These variations often dwarf the average differences between species that we obsess over in guitar forums.

The Real Variables Nobody Talks About

The study found that the wood's damping properties (tan δ) were:

• Almost completely frequency-independent in the range relevant to guitars (0.3 Hz to 70 Hz)

• Highly dependent on strain (how much the wood bends during vibration)

• Significantly affected by moisture content, especially in aged wood

In other words, how hard you play and how well you maintain your instrument's moisture content matter more than many of the wood species differences we obsess over.

The Science of Wood Selection

Let's get technical about how wood properties are actually measured and selected. When manufacturers test tonewood, they're looking at several key properties:

Density (ρ)

• Measured in kg/m³

• Varies significantly even within individual trees

• Typical ranges for common tonewoods:

  • Spruce: 350-500 kg/m³

  • Maple: 580-750 kg/m³

  • Mahogany: 500-600 kg/m³

• BUT: Individual samples regularly fall outside these ranges

Dynamic Young's Modulus (E)

• Measures wood's stiffness

• Ranges from 10-20 GPa for most tonewoods

• Can vary by up to 40% within species

• Measured through:

  • Vibration testing (non-destructive)

  • Stress-strain analysis

  • Ultrasonic testing

Damping Properties (tan δ)

• How quickly vibrations decay

• Typically ranges 0.005-0.02 for quality tonewood

• Measured through:

  • Free-free beam vibration tests

  • Forced vibration analysis

  • Dynamic mechanical analysis (DMA)

How Manufacturers Actually Select Wood

Guitar manufacturers use a combination of methods to select wood (when they do, and trust me most of them don’t) :

1. Initial Screening

   • Visual inspection for grain straightness

   • Density measurement through weight/volume

   • Basic mechanical measurements

2. Scientific Testing

   • Velocity of sound measurement (c = √(E/ρ))

   • Radiation ratio (R = c/ρ)

   • Cross-grain to with-grain stiffness ratio

   • Damping measurements at various frequencies

3. Characteristic Index (K)

   • Many makers use a combined metric: K = √(E/ρ³)

   • Higher K values generally indicate better acoustic properties

   • But: K varies more within species than between them

The Tap Testing Myth