What makes a great acoustic guitar for singers? While playability, volume, and responsiveness are important, it’s mostly how the vocals sit relative to the dominant frequencies of the guitar that are most important in terms of balance and separation as this prevents the natural tone of the guitar from overpowering the vocals.
Guitars with scooped mids are best for the majority of singers as the vocals usually span the lower mid to upper mid-range (100Hz and 8kHz). A guitar with less presence in the mid-range allows room for the vocals without being overshadowed by the sound of the guitar.
But, keep in mind acoustic guitars and how they are played e.g. fingerstyle, flat-picking, along with the vocalist’s delivery and vocal range, and the subjective nature of music in general mean there’s really no exact science to matching guitars to vocalists.
The sole purpose of this article is merely to provide a good starting point if you are a singer contemplating a new acoustic guitar.
Mid Range Scoop
The frequency range of the human voice
Unless you are playing instrumental music, vocals are generally the most critical component when playing accompanied. In simple terms, we are conditioned to hear the subtleties and nuances of the human voice, and we know when something doesn’t sound right.
The human voice is most prominent in the mid-range of our perceived frequency range e.g. the limits of what we can hear, which is between 20Hz and 20kHz.
Frequencies (Hz) are a measure of vibrations per second e.g. 1 Hz = 1 sound wave passing a fixed point per second) which defines pitch (you can read my guide to how digital music works here which covers a lot of this information).
Like all sounds, the human voice consists of a fundamental tone and series of overtones.
The fundamental is the dominant frequency in terms of the accuracy of pitch, and also the lowest. While overtones are responsible for articulation and timbre (the character of the sound e.g. what makes one instrument sound different from another).
For males the fundamental is between 100Hz – 300Hz, for females it’s more likely to be between 200 – 400Hz. But, when taking into account vowel and consonant sounds (articulation) the frequency range of the human voice is usually found between 100 Hz and 8 kHz with more of an emphasis on the fundamental.
A guitar with a dominant mid-range is often referred to as ‘nasally’. A scooped midrange, on the other hand, refers to the mid-range frequencies being attenuated e.g. reduced. This is simple enough to do with EQ, and is often referred to as the smile curve when dialed in on an equalizer.
But when considering an acoustic guitar, factors that affect the frequency response of the guitar including tonewoods and body shape have the most influence.
I know people who talk about wood like they are talking about EQ e.g. they look at particular tonewoods like an engineer might assess an equalizer.
How wood affects the tone of a guitar is largely based on the properties of the wood e.g. its lightness and ability to vibrate, its hardness, and density.
For example mahogany, a softer hardwood is known to accentuate mid-range frequencies and produce fewer overtones than other tonewoods such as spruce or cedar.
And, while mahogany is credited for contributing to a warm-sounding guitar with a strong fundamental, it’s not always an ideal tonewood for the singer/songwriter as there is typically less separation between the guitar and vocal.
I can attest to this, being the owner of an all-mahogany acoustic guitar. However, the strong fundamental does help with pitching and this may be just as important to you.
Again it mostly comes down to how the balance of vocals and guitar sounds to you and how it suits your vocal delivery and the unique characteristics of your voice.
Spruce, on the other hand, is a strong yet light wood, well known for its wide dynamic range, brightness and articulation.
As a result, it provides additional space for the vocals in the mid-range, and when paired with mahogany provides a balanced sound. When paired with rosewood the lower frequencies, in many cases are emphasized further, giving even more of a mid-range scoop in comparison.
It’s no surprise a huge number of acoustic guitar players/songwriters such as John Mayer, Paul Simon, Bob Dylan, McCartney and Lennon, Joni Mitchell, James Taylor, Neil Young, Willie Nelson, Eric Clapton, Ed Sheeran, and many more all play or have played spruce top guitars at one time or another.
Body Size and Shape
Of course, size and body shape also play a role in the acoustic tone of a guitar. For example, a larger guitar provides a larger surface area and internal cavity resulting in greater volume, and boominess, but the shape in terms of the width of the upper and lower bout, tightness of the waist, and size of the soundhole dictates how rapidly air escapes from the guitar body, also affecting tone and response.
Typically larger guitars project more volume and more bass but as we will discuss below, with regard to the Fletcher Munson Curve, the additional volume also gives the perception of additional high and low frequencies.
On the other hand, a parlor guitar, being the smallest standard body style available, offers a relatively broad waist and fairly narrow lower bout in comparison and is more mid-range dominant.
It’s also true that body size affects us in a mechanical sense.
For example, I’m sure I play my larger dreadnought differently from my more comfortable concert guitar, and this must have an impact on my attack on the guitar and how I hold a pick or where my hand rests on the bridge. There’s also the weight of the guitar to consider. A larger guitar or a guitar made from denser wood will be heavier and less resonant.
However, all things being equal, a dreadnought is well known for a boomy bottom end and greater clarity in the upper-frequency range providing balance for the human voice.
While smaller guitars tend to sound brighter with greater treble response purely due to the amount of air being moved compared to the larger guitar.
Some guitars are just too loud for some singers when playing acoustically. Over the course of a set, if you are playing acoustically and the guitar is forcing the vocal, the performance will be affected.
Size often equates to volume with regard to acoustic guitars, and therefore jumbo’s and some dreadnoughts can be overpowering for more intimate vocal deliveries.
If you are more of a strummer, with big, anthemic choruses and plenty of dynamics in your music then you need that volume but if you are more of an intimate performer, and play fingerstyle with softer vocals a smaller guitar will often be more suitable.
The Fletcher Munson Curve
Another thing to consider is how volume impacts the prominence of specific frequencies. How we hear a sound, essentially changes based on the volume we hear it at.
For example, at low volumes, we tend to hear a more pronounced mid-range but when the volume is raised the high and low frequencies are accentuated. While in reality, nothing has actually changed, we perceive sound this way. This also contributes to larger body guitars and their additional volume being credited with more bass response.
Again this will factor into what makes a good accompanying guitar for a vocalist, if the guitar you accompany yourself with is played in a more intimate, way e.g. fingerstyle compared to energetic strumming there will be a difference in tone that can be attributed to The Fletcher Munson Curve.
Based on the information above, a good starting point if unsure about the ideal acoustic guitar for you if you are a singer is a spruce top, rosewood back and sides dreadnought, or OM (orchestra model), which as attested to by the sheer number of singer/songwriters who play them are ideal for acoustic performances, but also versatile.
But, stepping back for a second, does any of this really matter?
It’s difficult to compare apples to oranges and this is almost always the case when comparing any two acoustic guitars. Even guitars made from the same wood can sound very different based on the luthier’s methods and the organic nature of wood in general, along with additional factors such as the age of the wood.
In fact, I’d argue that how the guitar is built often plays more of a role with regard to the character of the guitar than the ingredients the guitar is made from.
It also cannot be overstated how dependent the ideal guitar is relative to the singer’s vocal delivery and range e.g. while an all-mahogany guitar isn’t the obvious choice if considering leaving space for the vocal in the mid-range if your vocal delivery is more intimate an all Mahogany guitar may be just the ticket, take Nick Drake for example.
So, take the information above on board but keep in mind no two vocalists or guitars ever sound exactly the same and what really matters is what your ears tell you.