Nerd Words: Scientific Guitar Terms

A Brief Guide to Science Speak

I get it. You're interested in learning some of the science behind the instrument you love, but you didn't major in a technical field, or you've just never heard some of the terms before. Fear not, we here at Scientific Guitarist provide you with this handy guide to some of the technical terms you may come across. This page will be regularly updated as new terms come up in articles and the like, but if there is a word or phrase that you want us to add, contact us and let us know. We'll see what we can do.

Amplitude: The strength of a signal. A higher amplitude signal is a stronger signal.

Attack: The response characteristic of a system to a sudden transient.

Bit Depth: The number of bits used to represent a single sample of digital signal. CD quality is 16 bit.

Compression: The region of a sound wave's greatest amplitude.

Decay: The response characteristic of a system after the initial transient.

Decibel (dB): Signal amplitude represented in a logarithmic scale as opposed to a linear scale. Very useful for representing a very wide range of numbers, such as the human hearing range.

Diffraction: The spreading of sound waves that occurs as they move through an opening.

Diffusion: The scattering of sound waves as they hit an irregular surface.

EQ: Short for equalizer or equalization. Equalization uses an equalizer to alter a signal's frequency response.

Frequency: The number of times per second that a signal cycles through. Measured in Hz.

Frequency Response: The relative strength of different frequencies in a given signal. Typically refers to the magnitude response.

Fourier Transform: A representation of the frequencies that compose a signal.

Ground Loop: A condition formed when there are multiple paths to ground in a circuit. Frequently results in hum induced on the signal.

Hertz (Hz): Unit of measure for frequency.

Impedance, Acoustic: The restriction of acoustic propagation through a medium by objects or materials.

Impedance, Electrical: The restriction of conduction of electricity through a circuit by electrical components.

Impulse Response: A representation of how a system reacts to a short, sudden burst of input signal.

Magnetic Permeability: The tendency of a material to become magnetic when placed in the presence of a magnetic field. Higher values mean stronger magnetic fields are induced.

Magnitude/Magnitude Response: Similar to amplitude but generally used in the context of frequency domain data. This is what is generally meant by frequency response. Commonly expressed in dB.

Medium: A material through which sound or vibration moves. Examples include air, water, wood, metal, etc.

Modulus of Elasticity: See Young's Modulus of Elasticity.

Pressure: In acoustics we generally are talking about air pressure.

Phase/Phase Response: A measure of delay in a signal or system represented in the frequency domain. Commonly expressed in degrees.

Phon: A measure of perceived loudness.

Propagation: The movement of sound through a medium.

Rarefaction: The region of smallest amplitude in a sound wave.

Reflection: The bouncing of sound waves off of another object.

Refraction: The bending of sound waves as they move through a medium.

Resonance: The act of an object vibrating at or near its resonant frequency.

Resonant Frequency: The frequency at which a vibrating object (string, air, piece of wood) most easily vibrates.

Sample Rate: The rate (number of times per second) an analog signal is sampled (measured) when being converted to digital. CD quality is 44.1 kHz.

Speed of Sound: The speed at which sound moves. Shocker.

SPL: Sound Pressure Level. The amplitude of sound pressure measured in decibels. Frequently uses A or C weighting.

Sustain: The length of time over which a note rings out. See also, The guitar world MacGuffin.

Tonewood: Yeah, right!

Transfer Function: The relationship between an input signal and an output signal for a system expressed in the frequency domain. Consists of both magnitude and phase responses.

Transient: A sudden input to a system. Sometimes refers to the initial response of a system when a sudden input is applied.

Weighting: The hardest part. Sorry, couldn't resist! Let's try that again.

Weighting: Emphasizing or de-emphasizing different frequency regions of a signal. For example, decibels are frequently measured in either A or C weighting.

Young's Modulus of Elasticity: The measure of how stiff a material is, or how much it deforms for a given amount of force applied. Commonly called Modulus of Elasticity.