DIY Ambient Sounds at the Museum

Posted in Education Outreach, Projects by Bill
10 Jan 2012
DIY Ambient Sounds at the Museum

In my little town known for Spring Break, there is a little museum called the Science and Discovery Center of Northwest Florida. I grew up in museums and love teaching kids science, so of course I am on a first name basis with everyone at the Center. In fact I have started volunteering to make improvements and repair exhibits. They don’t have a big budget, in fact they only have 2-3 full time staff so any improvements or repairs has to be done on the cheap. This is how I added some much needed ambiance to two of the exhibit rooms without breaking the bank. I’ve documented what I did here so other non-profit museums can replicate the design.

Tish, the Museum director, had told me one improvement she would really like to make was to add ambient sounds to some of the rooms. When the museum had few customers, the different exhibit rooms were deathly quiet. There were a few rooms that it was easy to imagine what accompanying sound would match the decor. One room had half of a full size boat against a mural of an ocean view with seagulls. Another was a room with only an exhibit on bones decorated to look like a hospital. Both were good candidates for the addition of ambient sound, however professional systems for museums start at $500/room and go up from there. I knew it could be done for much cheaper, and set out sourcing parts.

Mod 1

Starting with the speakers, I hit up my new favorite shopping site, Amazon. I found a pair for $35. Next was an Amp. I wanted something cheap, but still reliable and easy to use. I settled for this amp for $30. Next was something to play the sounds. This took me a while to decide on, but in the end I settled on the MP3Trigger board from Sparkfun. For $50, I knew it was reliable, would always start playing after getting power cycled, and could loop tracks fairly well. I did try to hack a few cheap mp3 players, but it was not appropriate considering this needed to be user friendly for the museum staff and dependable. To get the trigger board to loop a track, all I had to do was jumper a trigger. Various other supplies including a power supply, SD card, cables and speaker wire added up to ~$30. Here’s the setup: (click to enlarge)

The mp3Trigger is mounted in a sturdy Sparkfun box and connected to a 9V power adapter. An audio cable connects the Trigger board to the Amplifier, and finally speaker wire connected the speaker to the Amp.

A single jumper wire shorts the first trigger, causing the board to loop the first track indefinitely upon power up. The setup was tested for a while in my apartment until I was confident in the design and then I brought it to the Museum for installation.

Cutting a hole and installing the speaker

Securing the speaker

The room getting the sound system

Running the speaker wire

There was an office nearby that had a shelf for a train set controller in another room, so we ran the speaker wire in that direction and setup the amp and Trigger next to the train controller.

New home

Messy wiring, but it worked, the room had sound! The track consisted of waves and seagulls, which fit perfect with the setting of the room. I left the museum sweaty and covered in ceiling dust, but it was worth it.

Mod 2

The next weekend I dropped by the museum to see how the system was working, only to find it turned off! Turns out knowledge on how to turn the system on and off every day didn’t make it to all of the museum’s volunteers so no one could turn it on. That was something I had to fix. I had also been thinking of ways to further stretch the dollar on this project and realized that stereo channels was not needed in every room. What if I bought a second set of speakers for another room but used the same amp and MP3 trigger to provide the audio?

One room would have two speakers tied in parallel on one channel, the other room has two speakers in parallel on the other channel. I had to get a bigger amplifier to handle the four speakers and provide balance controls to be able to individually adjust volume in the different rooms. This increased the price of the amplifier to $51 which is still a savings compared to having two smaller amps.

In order to create one mp3 file with totally separate audio tracks for the left and right channels, I used Audacity to combine two files. All I had to do was pan one track fully left, and a second fully right.

Creating the mp3 file

I also picked up a 7-day timer to handle turning the sound system on and off every day. This would make sure all the effort would not go to waste by the system getting left off again.

Installing the second set of speakers

Beefier amp

7 day timer control

The installation went well the second time around, and much to Tish’s delight, she had two rooms with ambient sounds! And the system was automatic thanks to the 7 day timer. No more relying on the volunteers to turn it on every day. Next time the museum gets a little bit of money, there are more rooms that could use ambient sounds.

Parts List

Click on parts for website.

Part Quantity Price, EA Price, Total
Amp 1 $51 $51
Speakers 2 $35 $70
MP3Trigger 1 $40 (w/discount) $40
Power Supply 1 $5 (w/discount) $5
7 day timer 1 $15 $15
Speaker Wire 1 $15 $15
3.5mm to RCA cable 1 $5 $5
SD card 1 $5 $5
Total $206

For about $220, the museum now has ambient sound in two separate rooms. I actually donated all this equipment to the museum, bought out of pocket. Fell free to use the donate button at the end of the post to send me a donation. As you can see, it will likely go to a good cause.

If you are involved with education programs like museums, I recommend contacting Sparkfun for a possible discount. They provided me supplies for this project at 20% off.

Audio Tracks

The one topic I have not mentioned till know is where to get the audio tracks. I searched around for a while and found They had a good selection and compatible licensing agreement. For about $10 a track, I was able to get a track for each room.  In fact, I can even post the tracks here for you to have a listen.

Boat Room:[mp3player width=177 height=20 config=fmp_jw_widget_config.xml file=]

Bones Room:[mp3player width=177 height=20 config=fmp_jw_widget_config.xml file=]

If anyone knows of a better source, let me know by leaving a comment below.