True Acoustics is Complete, Full-Bandwidth Acoustics. No Limitations, No Filters, No EQ. It means designing for and addressing all energy of any kind or frequency which can be perceived by the human ear and the human auditory system: brian, nerves, cochlea, eardrum, earcanal, pinna…..
True Acoustics means we can hear greater levels of Clarity, more life-like imagery, increased subtlety of micro-dynamics and finer resolution of detail than ever before. Our sense of hearing has evolved physiologically and cognitively to a level previous generations were unable to achieve. Evolution is systemic, thankfully.
True Acoustics means our biological mechanisms and the electronic world that creates sound have both evolved to new levels of performance, making everything we’ve done for 100 years antiquated. While this sounds dramatic and shocking, it’s quite normal for any field of science or for that matter, much of the creative arts and most definitely pop culture. Things change, we evolve and adapt. The challenge is to evolve with the times and to build a better mousetrap. Step One: Understand the Mouse. In this metaphor True Acoustics is the equivalent of understanding the mouse, learn everything about the mouse: measure all the energy which we as humans can possibly hear, scientifically and subjectively. Not part of the sound energy, not some of the sound energy, not a filtered portion of the sound energy; ALL of the sound energy.
True Acoustics means knowing when to use the right tool for the right job. Sometimes the historical, traditional methods fit the project, caveats and all. Other times the latest technology and modernized methods are the only solution for the project creatively and acoustically.
Brief Examples of historical and traditional acoustical elements which we are evolving beyond as we approach the event horizon of True Acoustics. (by no means an exhaustive list)
Frequency Response and Human Hearing
It is still widely accepted that human hearing ranges in frequency from 20 hz – 20 khz. (Earthquakes to Cymbals Crashing) Basic math proves this incorrect. Any musician or first year science student can tell you that every sound has harmonics and sub-harmonics. Using 40khz as an example, is a fully audible frequency yet widely considered to be outside human hearing range. It has a subharmonic of 20khz which is the upper limit of human hearing and another at 10khz which falls dead center of the hearing range. And yet 40khz is considered to be twice the upper limit of human hearing. Subharmonics are generally softer (lower volume/less energy) than the original sound (fundamental frequency) which means if the original sound is loud enough, many subharmonics can be heard. For example, 60khz as a fundamental can be heard as a 15khz subharmonic if the 60khz is loud enough. In short, 60khz can be heard easily by human hearing if the volume is loud enough. Anyone who’s heard an old flourescent light fixture humming at high frequency or a Plasma TV buzzing understands this concept.
Once in Studio C at Westlake Audio we measured a single audio channel strip for frequency response. We were astonished to find it passed audio well beyond the hearing range, past 20 khz. As our test gear could not measure the upper limit of sound frequencies the console could handle, we went to the tech shop and got better gear. It turns out Rupert Neve’s V series console passed 160 khz with ease! Remember that 20 khz is the current accepted limit of human hearing. One has to ask oneself, why would the world’s premiere audio console designer create a desk that passes sound 8x higher than the upper limits of human hearing? Well to Rupert it was obvious. Harmonics and SubHarmonics. At 160 khz the subharmonics dropped well into the human hearing range and had a dramatic effect on the perceivable sound characteristics including dimensionality, clarity, depth, width, height, realism, grain and definition. All these characteristics of sound are critical in music production and are auditory cues for people to understand quality and timbre of sound and music.
Sound Energy and Human Hearing | The weighted scales of measurement
Acoustics and sound level energy have been measured by filtering out part of sound, adjusted for the limitations of human hearing. The standard measure of decibels has been adjusted for human hearing according to what is known as the “A” scale or more widely known as dB A. DB is short for decibel and “A” is one of 4 standards used for measuring db (decibels). This takes some of the existing sound energy and ignores it where it falls outside the curve, based on the limits of the human ear. In this day and age, True Acoustics measures sound energy using the “Z” scale, or dB Z. The Z scale measures all sound energy with no filters and no weighting or adjustments. Measuring all the sound energy is truly accurate. It allows for more accurate understanding of sound, acoustics and the perception of all the energy, not just some of the energy.
Isolation Measurements | STC, NIC and OITC
STC or Sound Transmission Class is a measure of sound energy passing through walls or barriers. Acousticians, Architects and engineers are well familiar with this unit of measure as it has been around since the mid 1900’s. The good news is it was one of the very first acoustical standards of measure which gave architects and engineers a tool to design and build with. The bad news is that it was one of the very first acoustical standards of measure, and does not measure either low frequency below 125 hz or high frequency above 4khz.
In the Mid 1900’s testing was largely tested using drywall and wood of a grade and quality which is no longer available, yet these tests are the measure by which over 80% of traditional acoustics are designed with today. With the advent of engineered drywall specifically designed for acoustical performance, new testing was done, but with test labs and acoustic technology dating back to the 1960’s. STC ratings are widely accepted as being a measure of sound isolation. True Acoustics reveals that STC averages sound energy in a limited range: 125hz to 4khz. The same rules of traditional acoustics considers human hearing to be from 20hz to 20khz. That leaves over 80% of human hearing unmeasured. Especially low frequencies such as bass notes, trucks, airplanes or trains. The origin of these decisions were based in a decision to use only part of the hearing range and also a lack of advanced measurement technology. Unfortunately we still use this standard today. Using STC today means 80% of all sound humans in 1947 could hear walks right through every wall built today. Which sadly everyone has experienced in an apartment or office structure or hotel room where the walls sounded paper thin to the point where you could hear conversations clearly between rooms.
True Acoustics Solutions
- Address everything. All the sound energy, all the air, all the surfaces, all the materials, all the structural components, all the sound sources, Everything.
- Measure everything using dB Z. The only way to understand what is Truly happening is to measure Everything. The only True measure of all sound energy is dB Z.
- Design for fundamentals, harmonics and sub-harmonics. True Acoustics is only True when considering all aspects of sound origination and control.
- Use the most recent updated standards: OITC, NIC, IIC. While they are still far from actual True Acoustics, they are far better than STC.
Summary | Wrapping Things Up
True Acoustics is the way of the future, hearing more clarity, imagery and dynamics than ever before, thanks to evolution in our hearing, innovations in quantum acoustics and advances in audio electronics.
The business of acoustics is the same as any other business. As with many things made by man, it is governed by many elements, often starting with status quo, economics, tradition and popularity, followed by performance and awareness.
As technology moves forward, so does performance. True Acoustics is the movement of technology into the forefront of human consciousness to help improve the way the man-made world sounds.
Thank you for reading and tune in for our next blog coming soon.