Loudness

We inherently understand loudness even if we don't understand how, it is measured or applied, we know that if something has 0 loudness, we hear nothing but if something is way too loud we experience pain. The two loudest recorded sounds in history were the eruption of the Krakatoa volcano, one of the most powerful volcanic explosions ever, and the detonation of the Tsar Bomba, the most powerful nuclear explosion ever. So, the more pain we experience we can safely assume that something is becoming louder. We don't measure loudness in levels of pain, rather we make use of a term called decibels or the shorter abbreviation being dB. 

The larger the number becomes the louder something is, an average quite room is around 35 to 40dB, a super quiet room can be 20 to 30dB with anechoic chambers being the quietest room we can make. Our theoretical maximum loudness on earth in earth’s atmosphere I think was quoted to be around 194 decibels.

What is the loudest sound ever recorded?

1. The Tunguska Event (1908): This was a massive explosion that occurred in a remote region of Siberia, Russia. While not technically a sound, the energy release from the explosion generated shockwaves that were recorded around the world. It's estimated that the explosion had the energy equivalent to 10-15 megatons of TNT and produced shockwaves that registered on seismographs and air pressure sensors globally.

2. Krakatoa Eruption (1883): The eruption of the Krakatoa volcano in Indonesia is one of the loudest natural events in recorded history. The sound of the explosion was heard up to 3,000 miles away and produced an estimated sound level of approximately 172 to 188 decibels. This is far beyond the threshold of pain for the human ear and could be heard over a significant portion of the Earth.

Both are epic in proportion and scale. ironically represent death and destruction, the flip side to being loud would be how soft of a sound have we recorded?

 In a very quiet and controlled environment, the threshold of hearing is often described as being around 20 micro pascals (μPa) of sound pressure, which is a very faint and almost imperceptible level of sound.

Ok so enough about history let’s get on with the show and talk about loudness and what it has to do with a transducer or a loudspeaker, in case you are wondering what is the difference or which is correct to use?

Both "loudspeaker" and "transducer" are correct terms, but they refer to different aspects of the device:

Loudspeaker: This term is commonly used to refer to the entire audio output device that converts electrical signals into audible sound. It includes the diaphragm, voice coil, magnet, suspension system, and frame (basket) as a complete package. When people talk about "buying a loudspeaker" or "installing loudspeakers in a sound system," they are typically referring to the entire speaker unit.

Transducer: A transducer is a more general term that describes any device capable of converting one form of energy into another. In the context of a loudspeaker, the diaphragm and voice coil assembly can be seen as the transducer part of the speaker. They convert electrical energy into mechanical vibrations and then into acoustic sound waves. So, when you refer to a loudspeaker as a "transducer," you are specifically talking about the components responsible for the conversion of energy. We will use speaker in context as we talking about the transducer in a box as to how loud it is for this conversation.

Loudness and its practical use. 

Nothing is loud or soft until we measure its loudness and in order to do so we need to define 2 basic requirements being the measured dB & the distance between the object making the noise and our meter. So, we pull out our decibel meter and something that makes sound, for the sake of keeping things interesting P pull out a decibel meter from my right pocket and out of my left pocket a hand grenade to up the level of excitement.

Pulling the pin, I drop the grenade and we both land up running for our lives 5 seconds later the grenade explodes, because we ran at maximum average speed of the average human, we can concluded from the point at which the grenade was dropped we covered a distance of 33 to 40 meters before the explosion. To be more scientific we measure the distance which lands up being 40 meters.

Most people even small children can understand that something becomes less loud as we move further and further way, the object making the sound never became softer, rather the effect of being further away changed how much of the loudness we received. This understanding means if we know how loud something is at "some distance" we can calculate backwards in a safe manner how loud the explosion was where we "would" of had been.

1 meter away is generally considered a good distance to be when measuring loudness, this includes speakers or other objects. Though some things are not safe to measure so close like our explosion.

If we are creating a movie and our scene has 2 people talking in a coffee shop our environmental noise might be 45 to 50dB, the camera is equally spaced away in third person between 2 people talking loudly at 60 decibels. Our scene captures me and you talking 50 meters away, pulling the pin and running away. The question is how loud should the explosion be in relationship to the camera and table to accurately represent the sound on the movie set if the explosion is CGI?

Well now let’s say the average grenade explodes and measures around 160dB, we need to define how sound becomes softer as we move further away and if we use 1 meter as the standard let’s keep our standard in meters. Now not many of you know the math behind this and you don’t really need to 100% so I’m going to paste a link to a free calculator sheet here:

https://www.omnicalculator.com/physics/distance-attenuation

If you follow the instructions correctly you will land up with an answer of 126 decibels. This in theory is still tremendously loud and might require 1 if not 2 18-inch driver to do so. What is incredible to grasp… consider our speaker is 95dB at 1 watt, we would need to crank our system with 1200+ watts just to make the explosion match what we see on screen to create a sense of realism and that is just madness. If our center channel has a sensitivity of 95dB and our speech is 60dB try and calculate how many watts the center channel requires to generate 60dB ????

Scary we need fraction of a watt for the softest of sounds to extremely large and powerful 18” speakers that requires 1000’s of watts, suddenly it becomes obvious that perhaps a 12” subwoofer makes less sense for loud cinema bass. Often smaller drivers that are designed around subwoofer application are much lower in sensitivity around 90 and less, to show you how critical it is to select a driver with a high sensitivity look at it this way. 

• 90dB at 1 watt sensitivity will require 3980+ watts to achieve our explosion
• 95dB at 1 watt sensitivity will require 1200+ watts for the same result

So recreating loudness can be really hard to do for movies, but knowing how loud something is at 1 meter or how loud something is at a distance we can calculate the loudness at any distance to recreate a scene accurately.

What about music though, how loud is loud in music?

Music by nature is a little easier to understand because the huge gaps in loudness are not so apparent unless somebody is rocking an atomic kick drum these levels while loud are not on the extremes of an action-packed movie that can be explosions to whispers.

Let’s look at some reference instrument’s being played loudly

• Acoustic guitar 70 to 80dB
• Piano from 60 to 70dB and in full finger smashing mode a little over 100 decibels.
• Singers can range from very soft 30dB to 80 decibels

With a full orchestra range into 110 decibels which again is very loud compared to everyday life and at these loud volumes for extended periods of time many musicians suffer from hearing loss.

Generally speaking, music and or playback is done so at comfortable levels, background music is typically below the level of conversation between people so 60dB or less. I like to listen to music around the level of what I would perceive the music to be played acoustically for the most part in a casual environment ranging between 70 to 80dB and a little more upbeat vibe of 90dB is comfortable in my personal space. To be fair to the people around you 90dB at sub base frequency will not fly well with neighbors or people around you at funny hours of the morning if you are in a complex or the houses are close together.

We have discussed a little about loudness using some real-life applications now let’s talk speakers, the odds are you might be in the market for a speaker be it replacement or just Diy. The choices can be tough as now days tons of brands are on the market all offering good value and you can be presented with 20 or 30 speakers all which fit it a defined price point. 

If you are looking predominantly at home audio speakers you should note that these speakers in general have less sensitivity overall when compared to Pa applications and it is not uncommon to see speakers have sensitivity values of 80 – 87dB with some being higher or lower. With Professional speakers having a sensitivity from 91 decibels to 100 on a woofer is not uncommon.

Which is right for you if its about having nice music that does not need to blow the roof off?

In short all will work just great, for an average room even a speaker that is 50 watts and has a sensitivity of 85dB is loud enough to enjoy, look at these little boom box Bluetooth speakers these little 4-to-8-inch speakers rarely go beyond 10 watts with some of the cheaper units only being 2-watt modules which is more than enough for background music. A typical speaker at 1 watt can be as loud as most instruments and someone singing. Power is potential loudness whilst our sensitivity is how loud we are at 1 watt 1 meter away

So, if you are hunting for a subwoofer pick 3 basic speakers, try selecting one with the largest Xmax and Fs value to help reach down super low.

Now pick the next best driver with good cone displacement but try find a speaker that has the highest sensitivity.

Last pick a speaker that is perhaps way bigger than what you wanted to build or even much smaller, this will help you understand how size could influence the outcome.

Now lets jump into Winisd and look at 3 subwoofers and a couple of specification sheets and lightly touch on loudness and how loud each driver can get thrown into a box as replacement drivers.

It is important to remember Watts is potential loudness, don’t think of the speaker that has more watts is going to be louder. Look at the sensitivity value which tells us how loud it is at 1 watt & the total power handling and the cone displacement combined. Next stop we will cover another graph on loudness which we had not discussed, I know tons of guys who have made enclosures and spent top $$$, when they start to review the product its not sounding as good on them lows because the skipped a section of understanding :) 

Love, peace & respect to all.