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Entries in Contact Mic (4)


Recording Drains

I am not the best when it comes to wiring up a studio.  Twice I've been involved with major studio re-wiring projects and both times I proceeded at about half the speed of everyone else.  Luckily this slow pace produces fewer errors, as I tend to check everything over and over before I actually start soldering or bust out the EDAC tools. I think one of the reasons I am so hesitant with this type of work is that I've lived for years with the results of my grandfather's gung-ho approach to DIY.  I remember when I was a kid, my grandfather would jump at any fix-it job that presented itself.  With all respect, he was not a very good handyman.  Every light switch in his house was wired up upside down and every faucet had hot on the right and cold on the left.  

My grandfather kickin' back after a long day's work at the cabin.

When I was a child I would spend long stretches of the summer at the family cabin which my grandfather and his father built from scratch.  When he installed the indoor plumbing, the job did not exactly adhere to building codes - and so the cabin to this day has a few unique features.  The one that has always stuck in my mind is the sound the kitchen sink makes when you pull out the drain plug under a full sink of water.  As the water drains down, everything is normal... until the last moment when a huge suction noise starts building to a loud climax. 

The cabin has no bathtub, only a shower, so babies and toddlers have always been bathed in the kitchen sink. A classic prank to play on an unsuspecting young one is to leave them in the sink as the water drains... and then watch the child freak out when the water runs out and that tremendous sucking sound blasts from underneath them.  

One of my cousins chillin' in the sink about 40 years ago.

The cabin is now over 50 years old and lots of renovations and repairs are taking place every summer.  It occurred to me recently that the sink drain had to be recorded before someone went and had the plumbing fixed and that sound was lost to the world forever. 

I grabbed my contact mic (my Aquarian Audio Hydrophone with the contact mic adaptor) and gaffer-taped it to the underside of the sink, pointed a shotgun mic (in this case a Rode NTG3) at the drain from above and pulled the plug.  Here are the results (turn it up loud!!)

Imagine being 2 years old, sitting naked in the sink, and that sound comes roaring out underneath your bum.  It was terrifying, I can tell you from experience. 

Contact microphone taped to the bottom of cabin sink. The tape did not hold it tight enough so I had to manually push the mic up against the metal while recording. Not ideal but got the job done.

The shotgun mic captured the sound really well, while the contact mic on its own is not a very interesting sound: too much low end and not enough definition.  But when you combine the two it gives a great, full effect of the suction's power, with detailed high frequencies and tail-offs.  Here are a few different takes of the drain with the mics isolated and then combined. (shotgun/contact/combined)

Cabin Kitchen Sink by azimuthaudio

When I got home from the cabin I decided to try the same recording set-up on my own (newly installed) kitchen sink.  On my first try I got nothing; the water just washed down the drain making very little noise, but with a few experiments I figured out that by plugging one side of the double sink and pulling the plug on the other side I could get a good sound.  There is no dramatic suction noise at the end, but the actual draining of the water is much louder and better defined.

House Kitchen Sink by azimuthaudio

My last sound in this post is a recording I made by putting one of my DPA 4060 miniature microphones down past the drain of a dry sink while the water was running a little further down the water pipes.  This captures a great hollow metallic reverb. Last year I worked on an episode of an animated series that took place in a sewer pipe beneath the city, and this recording would have been extremely helpful on that project.  I know it'll get used in the future.




Chipmunk Feet

In the forties, my great-grandfather and my grandfather built a summer cabin. It sits on a perfect parcel of land with a spectacular beach on a small lake.  This cabin has stayed in my family and I am lucky to be getting great weekends out of it over sixty years later.  The summer months at the cabin are divvied up between my many family members, and this past weekend was my first chance this year to go up and spend some time on the beach. 

View from the beach at the cabin during sunset.  Photo Credit: cabin guest Kassandra Wu

One of the bizarre but fun features of life at the cabin are the antics of the unusually friendly resident chipmunks.  These little guys seem to have very little fear of humans.  In fact, if you offer them a few seeds they will come and eat them right out of the palm of your hand.

My wife feeding a hungry little chipmunk

As I was sitting reading on the deck, the little chipmunks were constantly running by, chasing each other around.  So distracting was the sound of their tiny little feet on the wood planks of the deck that I decided to put down my reading and record these little guys.  My first instinct was to get out a shotgun mic but I quickly realized that with my niece and nephew playing in the water a hundred yards away and all the motor boat traffic out on the lake I would not be able to get anything of much use, seeing as the chipmunk scrabbling was so quiet relative to all that noise.  Instead I went with plan B and got out my H2a-XLR hydrophone and the adaptor cup that turns it into a contact microphone.

In order for the H2a to work as a contact mic you need to put a tiny amount of water inside of the rubber adapter before you insert the mic into it.  Since I was trying to attract little rodents to the microphone I figured I'd up the ante and use a bit of red wine instead of water, thinking the smell might attract their attention. I placed the mic on the deck and surrounded it with seeds.  Then I hit record and sat down a few feet away.

It wasn't long before the first chipmunk sniffed out the goldmine of seeds and came to gobble up as many as he could stuff into his fat little cheeks. This lucky first chipmunk had vacuumed up almost all the seeds when suddenly six other chipmunks skittered in, vying for their share.  They were taking turns, one stuffing his face until the next one would show up and chase off the first.  The seeds were gone in no time, but they kept coming back to try to collect any morsels that might have been left behind.

Here is one with its cheeks stuffed full of seeds making a getaway.

The sounds of them running around on the deck are pretty interesting.  Different planks of wood on the deck would resonate slightly differently due to the various lengths of wood.  So as the chipmunks scampered up onto the deck and towards the mic I could make out a weird little marimba melody.  Using the contact mic wasn't going to capture the sounds of them eating, but it was great for the footsteps.  Here's a video of the chipmunks running around near the mic.  The audio feed for the video is straight from the mic you see on the deck.

I love the sounds when they scoot right past the mic.  It's a great active mix of wood taps, scratches and scrambling feet.  I am not sure I will ever have a need for chipmunk feet on wood,  but I am positive this material will come in handy when I'm designing something else entirely someday soon.

As a footnote, I think my idea to use red wine instead of water to lube the contact mic adaptor might have gotten one of the chipmunks a little impaired.  At one point, after all the seeds were long gone, one of the little guys was snooping about near the mic for a quite a while. Another one eventually arrived to chase him away and he turned to run - and bolted straight into a chair leg!  Yikes.  Luckily, he had only travelled a few inches so he apparently had not worked up enough speed to hurt himself. He quickly recovered and took off in another direction.  I have never seen a chipmunk run into anything before.  I wasn't shooting video at the time but I was rolling on the 702 so I have a recording of a drunk chipmunk hitting a chair leg.  Poor little fella. Listen about 10 seconds into this clip for the unfortunate incident:

Chipmunk Passbys by azimuthaudio

One of the chipmunks hiding behind my SD 702 recorder, waiting for the coast to clear of other chipmunks so he could go back for more seeds.



Scrapes, Squeals, and Grinds

Recently I took my recording rig with me on a trip to visit my wife's hometown.  My father-in-law runs a small sign printing operation out of a converted barn and I thought I could spend some time in the shop recording the various machines.  He has been in the printing business for almost 40 years and has some great devices from the pre digital days.  Although I got some great stuff from the various kinds of printing press and machines my favourite sound discovery was the drying racks.  

As you can see the rack consists of 25 levels of metal trays, each level is spring loaded so it can be lifted upwards to get at the tray beneath it.  It works almost like a giant metal book.  They are designed so that you can air dry multiple prints at the same time, all stacked on top of each other.  The racks are not very loud when listened to normally, but if you place a contact microphone on the rack and listen through it - a whole new world of sound appears.

I have not used any processing on this at all, all the reverb you can hear is the actual rack resonating, and man can it resonate a long time.  Just walking near the racks set them off on long slow metallic rings that seemed to last forever.

In this first sample I am simply raising and lowering the 15 racks above the one the contact mic is resting on. It basically becomes a horror film sound track.

Dans Shop Metal Grinds B by azimuthaudio

The drying rack was originally a stack of 50 individual racks but in order to get it to the second floor of the barn it had to be split into two units of 25 racks each.  The second unit sounded similar but had a lot more presence from the actual springs attached to each rack.  You can hear the springs "popping" quite a bit in this recording of the second unit.

Dons Shop Metal Grinds A by azimuthaudio

Another great sound I stumbled upon was simply lightly kicking the bottom of the rack to get this great low metal hit.  You can hear a couple at the begining of this clip followed by more grinds of the trays being lowered and raised.

Metal Grinds Dons Shop Contact Mic 2 by azimuthaudio


Stomach Rumbling


Recently my wife was complaining of a sore stomach at around 2am and instead of asking what I could do to help, I darted out of the room and came back with my recording rig and a contact mic (Aqarian Audio H2a-XLR Hydrophone).  It turns out her stomach was not upset in a very dramatic fashion in terms of the audio it was producing.

Ehrin Belly by azimuthaudio

So I slapped the mic on my stomach and realized it was a gold mine.  My stomach was not upset at all but it was rumbling up a storm.  

Timothy Belly by azimuthaudio

 While I was at it I put the mic on my chest to grab some heartbeat sounds.  If you have a sub woofer take a listen through it because my heart was pounding out the lowend.  Strangely about 10 seconds into this clip my heart kind of stutters a bit.  Maybe I am going to have to keep tabs on this.

Heartbeat by azimuthaudio