The Bath Tub in the Woods

I grew up in a rural area outside a small coal-mining town in eastern Kentucky. My childhood home was nestled in a little valley formed where three mountains met. The house itself sat on maybe 2 acres, with a small creek running along the back edge. Across the creek and up a dirt road, my parents owned a fair amount of mountain property we referred to as “the holler.”

It was in the holler that I spent much of my childhood – exploring the hills, building hideouts, monster hunting, and playing in old abandoned mines from generations past. (That last bit my mother was blissfully ignorant of. So let’s keep it between you and me, ok?)

One summer, in the midst of an adventure undoubtedly of epic proportions, I stumbled across an old green fiberglass bath tub. I had no idea how it got there or who put it there. But there it was, surrounded by tall weeds and filled with all the gross stuff that things abandoned in nature tend to accumulate. I stared at it for a bit. And then found a big stick to bang around on it in hopes of scaring away any poisonous snakes that might be lurking around. I flipped it over one way and then another. And then somehow I managed to stand it up on its short end so that it stuck straight up in the air.

It was a little dirty, yeah. But it would do. This would be my fuselage.

You see, the movie “Explorers,” starring River Phoenix, Ethan Hawke, and the third guy who never gets the recognition he deserves, had just come out the year before. And I was obsessed with it. The notion that three kids could build a spaceship out of junk and a computer wasn’t just a fantasy for me. It was a blueprint. A blueprint I was convinced I could follow. I just needed to find the right stuff. And, um, learn about computers.

We were, in fact, too poor to have a computer. I don’t think I had even touched one up to that point. But that didn’t stop me. I spent all summer collecting random bits of junk for my ship. Old hoses, sparkplugs, pipes, wires, etc. Everything had a purpose. I just didn’t know what it was, but I was sure the thing would tell me in time.

I had also gotten my hands on quite the collection of “3-2-1 Contact” magazines. Each issue had snippets of BASIC code in it for kids to try out. I didn’t understand a lick of it. But I was sure some magic could be found in there. Like a witch brewing her stew, I could take a little of this and little of that and everything would find its own way to become what I needed it to be.

I worked on and played in this ship for weeks.

Eventually, school started again. Summer gave way to fall. And though that particular adventure’s time had passed, the places my mind took me, the things my eyes saw, and the extraordinary reactions of all the imaginary people passing below me as I flew over them were all important. Not only did they provide an escape for me from a home in conflict, but they fueled even more wonderful adventures later on, teaching me about myself and helping me to learn that ambition and curiosity is a powerful combination.

The tub is gone now, carted away. The ground beneath it has been bulldozed over and now a house sits there that was built by a young couple who eventually purchased the land. I imagine there are still bits and bobs left over from that project, buried deep in the dirt that’s been imprinted with my stories. Artifacts from a little boy’s exploration into the unknown.

I like to think that in a parallel universe, little-boy-me actually succeeded in getting that ship off the ground.

Building a LO-LA Night Light

When Droid Division released their 3D model of LO-LA from the Obi-Wan series last year, I immediately knew I wanted to build a night light for my kids. The following video shows how I did it.

Links of things mentioned in the video:

Droid Division Etsy Shop:
M.M’s Prop Shop LO-LA Video:
19mm Latching Push Button Power Switch w/ Blue LED – EBay
9mm Stainless Steel Tube
5V Power Adapter –
EDGELEC Assorted LEDs (Prewired) –
14 mm Clear Glass Domes – EBay
5.5mm x 2.1mm Female Panel Mount Connector – EBay

Music Credits:

xii by Limujii
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Track: El Verano — Declan DP [Audio Library Release]
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Music: Highfly by Jay Someday is licensed under a Creative Commons License.
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Days Like This by Jay Someday
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Swimming Pool by Aftertune
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Music | Imagine by Declan DP
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Decibels and dB SPL

(Note: This is a slightly modified excerpt of Chapter 1 from a book I’ve been working on entitled “Digital Audio for C++ Programmers.”)

The decibel is perhaps one of the most confusing and misunderstood topics in audio. It has a confusing formula that appears to change based on the context. It’s also used in a variety of applications beyond audio. In fact, much of the documentation you’ll find is actually related electronics and telecommunications. And to muddy things even more, by itself the plain ole decibel doesn’t even really convey much meaning. It merely relates one power value to another. So, if after reading this article, you still find decibels confusing, don’t fret. You’re in good company.

The decibel originated with telephony in the early 1900’s. It was used as a way to describe the power efficiency of phone and telegraph transmission systems. It was formally defined as 1/10th of something called a bel. Interestingly, the bel was rarely used. The decibel got all the glory. The decibel has since found its way into all sorts of other domains, such as optics, electronics, digital imaging, and, most importantly to me, audio.

There are two benefits to using the decibel. The first is that switching to a logarithmic scale converts an awkward range of values (e.g., 0.0002 Pascals – 20 Pascals) to something much easier to reason about (e.g., 0 dB SPL – 120 dB SPL) . The other benefit applies to audio – a logarithmic scale is much closer to how the human ear actually hears. With a linear scale, like Pascals, doubling the value doesn’t usually feel like a doubling of loudness. With decibels, we actually get a scale that’s much closer to how to perceive loudness.

The decibel, in the generic sense, is not strictly a physical unit. When we think of physical units, we typically think about things like Amperes (number of moving electrons over time), Pascals (pressure), meters (distance), Celsius (temperature), etc. These are absolute units that correspond to physical things. The decibel isn’t like that. It’s a relative unit. It provides a relation of two things, which are themselves physical units. And it does this on a logarithmic scale.

The general formula for the decibel is as follows.

The decibel, abbreviated dB, is the logarithmic ratio between two power values. One of these two values is a reference value. The other is a measured value.

You may notice the phrase “power value” in that formula. In physics, this means the amount of energy transferred over time. The unit for power is usually the watt. However, there are plenty of units used that aren’t power values (such as Pascals in acoustic audio). So we have to convert those units into something related to power. This typically just means squaring the measured and reference values. The decibel formula ends up looking like so.

With logarithms, we can pull that exponent out and turn it into a multiplication.

This can be simplified even further like so.

And this is the formula you’ll most likely encounter when applying the decibel to measured and reference units which aren’t power-based (like Pascals in acoustic audio). It’s just a derivation of the original formula with the measured and reference values tweaked.

Standard Reference Values

A lot of domains, such as electronics and audio, have standardized reference values for the various things being measured. When we talk about these standardized flavors of the decibel, we add suffixes to the dB abbreviation. Examples of this are dBV (voltage based), dBm (radio power), dBZ (radar power), etc. The one we’re most concerned with in the field of acoustic audio is dB SPL.


dB SPL is the most common flavor of decibel for indicating the loudness of acoustic audio. SPL stands for sound pressure level. The reference value used in calculating dB SPL is the threshold of human hearing – 0.000020 Pa. We plug this into the decibel formula along with a measured value, also in Pascals, to come up with a dB SPL value.

A measurement of 0 dB SPL is considered the threshold of human hearing. That is, it’s the quietest sound that the human ear is capable of hearing. On the upper end of the scale, somewhere between 130 dB SPL and 140 dB SPL, is what’s referred to as the threshold of pain. When the volume of sound approaches this level, it can result in physical discomfort and some amount of hearing loss is almost certain.

The following two tables shows some common sounds and their approximate sound pressure measurements. The first table shows measurements in Pascals. The second table shows them in dB SPL. Compare them and you’ll see that dB SPL is much less awkward to use.

Sound SourceDistance from EarPascals
Jet Engine1 meter632
Threshold of PainAt ear20 – 200
Yelling Human Voice1 inch110
Instantaneous Hearing Loss Can OccurAt ear20
Jet Engine100 meters6.32 – 200
Chainsaw1 meter6.32
Traffic on a Busy Road10 meters0.2 – 0.63
Hearing Loss from Prolonged ExposureAt ear0.36
Typical Passenger Car10 meters0.02 – 0.2
Television (typical volume)1 meter0.02
Normal Conversation1 meter0.002 – 0.02
Calm RoomAmbient0.0002 – 0.0006
Leaf rustlingAmbient0.00006
Threshold of HearingAt ear0.00002
Sound Pressure Measured in Pascals, “Sound pressure” Wikipedia: The Free Encyclopedia. Wikimedia Foundation, Inc, 22 July 2004, Accessed 29 Nov. 2022.

Sound SourceDistance from EardB SPL
Jet Engine1 meter150
Threshold of PainAt ear130-140
Yelling Human Voice1 inch135
Instantaneous Hearing Loss Can OccurAt ear120
Jet Engine100 meters110-140
Chainsaw1 meter110
Traffic on a Busy Road10 meters80-90
Hearing Loss from Prolonged ExposureAt ear85
Typical Passenger Car10 meters60-80
Television (typical volume)1 meter60
Normal Conversation1 meter40-60
Calm RoomAmbient20-30
Leaf rustlingAmbient10
Threshold of HearingAt ear0
Sound Pressure Measured in dB SPL, “Sound pressure” Wikipedia: The Free Encyclopedia. Wikimedia Foundation, Inc, 22 July 2004, Accessed 29 Nov. 2022.

There are instruments available that measure sound pressure levels and report dB SPL. One such instrument is shown below. This happens to be my personal db SPL meter.

These devices are fun to take to concerts or demolition derbys if for no other reason than giving you the intellectual authority to complain about permanantly damaged hearing.


Hopefully, this article has helped demystify the decibel. Mathematically, they’re not something to be feared. It’s usually the logarithms that scare folks away. And if you’ve long since forgotten how logarithms work, go brush up on them and come back to this article a second time. It will make a lot more sense.

If you found this content useful, or if something could have been explained better, please leave me a comment below.

Until next time.