Part of me wants to believe people when they talk about the importance of 20hz and infrasonic capable subwoofers, but to be honest, I'm kind of wondering how much of that is legit
20 Hz makes sense, but is technically difficult to implement in normal living rooms.
To radiate 20 Hz cleanly, you need a large cone area, a large excursion of the woofer and yet low distortion.
You also need high amplifier power and tuning to the room in question.
Feasible, but not easy.
That's why we usually limit ourselves to the contra octave instead of the subcontra octave, which is technically easier to implement - and covers approx. 97% of the program material.
The full range of human hearing spans roughly from 20 Hz to 20,000 Hz (20 kHz). This range can be divided into octaves, where each octave represents a doubling of frequency.
The subcontra octave begins at around 16 Hz and extends to 32 Hz. These are the lowest frequencies, often more felt than heard. They appear in pipe organs, cinematic sound design, and electronic music for powerful low-end effects.
Next is the contra octave, ranging from 32 Hz to 64 Hz. This is where you find the deep tones of instruments like the double bass or the lowest keys on a grand piano. It provides the foundational weight in music.
The great octave spans 64 Hz to 128 Hz and contains essential bass frequencies found in kick drums, bass guitars, and low toms.
The small octave runs from 128 Hz to 256 Hz. This is where the lower midrange begins, covering the fundamental tones of many male voices and deeper instruments.
The one-lined octave covers 256 Hz to 512 Hz, including many musical fundamentals and forming a key part of the tonal body of acoustic instruments.
The two-lined octave ranges from 512 Hz to 1024 Hz (1 kHz). This upper midrange area is crucial for clarity and speech intelligibility.
The three-lined octave lies between 1 kHz and 2 kHz, and the four-lined octave spans 2 kHz to 4 kHz. These areas contain many upper harmonics and strongly affect the presence and definition of vocals and instruments. Human hearing is especially sensitive in this range.
The five-lined octave runs from 4 kHz to 8 kHz, containing very high overtones that contribute to the brightness and brilliance of sound. However, excessive energy here can sound harsh or piercing.
Finally, the six-lined octave stretches from 8 kHz to 16 kHz, and the range from 16 kHz to 20 kHz—while not a full octave—is still part of the uppermost audible spectrum. These frequencies add "air" and shimmer to audio, although they carry little tonal weight. They are mostly perceived by younger listeners with healthy hearing.
The key point is that an octave is defined by a doubling of frequency, not by a fixed number of hertz. Each octave represents a ratio of 2:1. So for example:
From 16 Hz to 32 Hz is one octave (16 × 2 = 32),
From 32 Hz to 64 Hz is another octave,
And from 8 kHz to 16 kHz is also one octave.
Even though the higher octave spans 8000 hertz in absolute terms — compared to just 16 hertz in the subcontra octave (16–32 Hz) — they are musically equal in width, because both represent a doubling in frequency. This can feel counterintuitive at first, because as frequencies rise, each octave contains more hertz numerically. But the human ear perceives pitch on a logarithmic scale, not a linear one. That means we hear equal ratios (like doubling) as equal steps in pitch.
For example, going from 100 Hz to 200 Hz sounds like the same size pitch jump as going from 1,000 Hz to 2,000 Hz — even though the second jump spans ten times more hertz. That’s because our perception is based on the relative change, not the absolute number of hertz.
This is also why musical instruments, EQs, and audio processors are designed around logarithmic frequency behavior: doubling the frequency always equals one octave, no matter where you start.
So, to answer your question: the last octave (e.g., 8 kHz to 16 kHz) contains more hertz numerically, but not more musical "space" than the first octave (e.g., 16 Hz to 32 Hz). Each octave is equally wide in musical terms, because our hearing interprets frequency proportionally.
So yes, subcontra octave from 16hz to 32 Hz is very useful, but difficult to implement and corresponds approximately to the musical information in the upper frequency range from 16khz (8khz?)
You always have to decide for yourself what is important to you.
I myself have no problem with a well-reproduced 30 Hz to 16 kHz.