Interesting aging process

[Boda Getta]

From the Hudson Four Grain Bourbon writeup:
" The warehouse is lined with heaters that power the distillery’s stills. As a result, when the stills are running during the day, the warehouse becomes incredibly hot, causing the oak casks to expand and interact with the whiskey. In addition, each night, when the stills are dormant and the temperature cooler, speakers, which have been placed throughout the warehouse, play loud rap music with deep bass. The deep bass agitates the whiskies, and causes the barrels themselves to experience micro-expansions and contractions. This sonic aging process – unique in the industry – adds to the interaction between the oak and the whiskey."

I just wish they could find some other bass rich music to serenade the whiskey.

BG

[Bushman]

That is interesting, some of the larger micro distilleries I have been to have to keep their aging barrels in a separate room or building incase of fire they don't want them in the same area as the still. Of course one of the permits is a from the fire department and they could be different from area to area.

The music has been used by others, I think Woodshed said he does it at night. I have a hard time believing that you could get enough vibration from the music to shake those heavy kegs but I have had muscle cars pull up next to me with their music blaring and believe they rocked my vehicle.

[chrig]

The more I read the more interesting this hobby becomes!

The bass thing I can easily understand having previously dabbled in car audio competitions where systems would rattle garage doors from hundreds of meters away. Low frequency (sub 40hz) sound can be a very powerful thing!

[Jimbo]

Thats a great idea! Both of them, the heaters and the sound. I believe that would work, there is a train line almost half mile from my house. I have pennies jammed in the mullion bars on my bedroom windows because the vibration rattles the damn sticks against the window. Its not a vibration you can feel, but it sure as shit rattles them sticks against the glass enough to wake me up.

[Brutal]

Truck with serious bass
http://youtu.be/CKxcNc8KSRk

[spisska]

I have a hard time believing that you could get enough vibration from the music to shake those heavy kegs [...]

That's the great thing about this process -- you don't *need* to shake the kegs.

Sound is a pressure wave, and will go straight through the barrels and out the other side, subjecting the distillate inside to high-pressure and low-pressure as the sound wave passes through.

Bass frequencies are much better for passing through obstacles, since they have long wavelengths and carry much more energy. The higher the frequency, the less energy is required to produce the sound, and the more easily the pressure wave will be absorbed by walls or other obstacles and/or reflected. Ever stand outside of a music/dance club while the show is going on inside? What did you hear? Ever wonder why dolphins use high frequency chirps for echo-location, but whales use low frequency songs for long-distance communication?

This is why in a symphony orchestra, the high-pitched instruments like flutes and violins are in front, while the low-frequency instruments like contrabasses and tubas are at the back. It's also why tubas are so much bigger than trumpets -- a tuba player has to move a lot more air than a trumpet player to make a sound, and that's reflected in the higher energy within a tuba wave than a trumpet wave.

Here's some fun information: The wavelength for a specific frequency is the speed of sound divided by frequency in Hertz (cycles per second). At sea level, sound moves at roughly 340 m/s. The lowest pitch at which most people can hear a sine wave is 20 Hz, which produces a wavelength of 17 meters. If you were subject to a 20 Hz sine wave, it's unlikely you would perceive it as a resolvable pitch, but far more likely as a ground-shaking rumble. Most commercial audio recordings roll off frequencies below about 100 Hz, which is a 3.4m wavelength. Too much sound below that and the recording sounds muddy and can damage speakers if played at high volume.

The highest frequency a person with healthy hearing can hear is around 20 kHz, which has a wavelength of around 17mm. But, if you are over the age of around 30 and/or have had exposure to a moderate amount of high-pressure sound waves (such as power tools, rock concerts, lawn mowers, etc) it's unlikely you can hear a 20 kHz tone at all. This is why there are some products marketed as "teenager repellents", which basically emit sound waves in the 17 kHz to 20 kHz range that grown-ups can't hear but teenagers still can.

I've been reading a bunch here about ultra-sonic methods to hurry aging, by my gut is telling me that low-frequency might be more effective. Which is better? Changing pressure by a tiny amount around 30,000 times every second, or by a much larger amount at <50 times every second?

Of course, you could pump a lot more power into the high-frequency rig, but don't do it you have a dog. Dogs can hear frequencies up to ~60 kHz, and subjecting a dog to a constant buzz at >25 kHz and < 60 kHz would amount to animal torture.

More research is clearly required ...

Another fun fact: Ever wonder why so many polkas and other European oom-pah music is written in the keys of G and C, while so many jazz songs are written in Bb and Eb? Many of those songs were either written or definitively arranged in the first half of the 20th century, when electric lights and electricity in general were much more noisy than they are now. Europe's power grid runs at 50 Hz, which is basically G (49 Hz), while the US power grid runs at 60 Hz, or basically Bb (58.3 Hz). Old stage lights were loud, and I absolutely believe that players tried to play in tune with them.

[Jimbo]

Great post spisska, very interesting stuff.

[Bushman]

Learn something new everyday!