In a small pine forest, I installed 3 talking stations where the visitors were invited to walk, think, and smile for about ten to fifteen minutes. The messages were heard at random and the sequences were (almost) never repeated. Every station had about 100 different files or messages triggered by a PIR detector.
This project is developed in 3 steps: writing – recording – installing.
Step 1: Writing the Script
You need to know first where your audio station(s) will be installed. For instance, if in your trees, many squirrels are at home, one or two quotes might talk of that. I would say: “If you have lunch under the shade, don’t bring any mustard or mayonnaise, squirrels will provide the condiments” or if your visitors are savvy teachers, I would quote Wittgenstein: “Whereof one cannot speak, thereof one must be silent.” Or a second one: “If a lion could talk, we could not understand him.” Etc. (Easy to find on the web). At least 30 tweets are needed for a fair random. I prefer to use about 100 quotes per station. And if you install 3 stations, the sequence gives an almost “Artificial Intelligence” result.
So, open your word processor and write until you are satisfied with the result. Be patient. The success of the project depends upon the quality of your quotes. Print your text.
Step 2: Recording the Audio on a Computer
For this step, you need:
a- a talent with a nice speaking voice,
b- an audio recording software, like Audacity (free), Sound Forge or even an iPad.
c- an SD/SDHC memory card with 1 or 2 Gb.
The recording is done in stereo 44,1 kHz 16 bit .WAV or MP3. The files at the end have short names like 001.wav - 002.wav. …999.wav. Don’t write 999 quotes, it’s too much. Every quote becomes a file.
If you don’t have a software installed, try to download Audacity. It’s free and you could find many Instructables on how to perform an audio recording with a microphone and this software.
The talent records all the quotes in a single file. In case of a mistake, he makes a pause and goes on. He repeats the quote twice and then a few seconds of silence. This is usually a task that is done in a relatively short session.
The editing is a little boring but not too long. In a file we find: “The quote, the quote repeated and 8 seconds of silence”. Save as: 001.wav
All those files are placed in a directory named 1R0. R stands for random and “zero” for playing a single file. The first “one” stands for a file waiting to be triggered.
The question is: Why a few seconds of silence? The visitor is asked to walk slowly but you always find a smart “trigger happy” guy who doesn’t listen, he only wants to retrigger the system. Believe me, he’ll walk and take time to understand the talking tree.
Step 3: Installing the Audio Station
Player – Speaker – PIR detector - Battery
You need an audio player able to play at random only one file when triggered and that cannot be retriggered before the file is completely read. That’s why there is a pause at the end of every file. I chose NanoPlayers from www.id-al.com . Send an Email to firstname.lastname@example.org and ask how to buy those players in US. It’s also nice to add a remote control (also from id-al) to adjust the volume on site. The NanoPlayer-box is sold in an enclosure but it’s cheaper to buy the OEM version with the printed circuit only. I prefer to have also their small bracket as an accessory. It becomes a heat sink and it’s easier to screw everything behind a speaker for instance. Insert the SD/SDHC card. Only a small screwdriver is needed to connect the power supply, the speaker and the PIR detector. If you build more than one station, only one remote control is needed for everything.
Look in your basement and find an old speaker in an enclosure. Any 8 ohm speaker is ok. The NanoPlayer has a good audio amplifier to drive it. The NanoPlayer is stereo, use 2 speakers if you like. Only a short wire connects the speaker to the terminals on the player. Screw the NanoPlayer behind the speaker.
If you want to let your station outside, place the NanoPlayer in a plastic box with the battery and find a horn speaker in plastic.
The infrared detector is the kind used in an alarm system. My PIR detectors come from www.frightideas.com . The contacts must be NO (normally Open) Some PIR are NC and cannot be used, take care. The NanoPlayer and the PIR are powered by a 12 volt battery. The circuit is easy to follow on the PIR and the NanoPlayer. I like to solder 2 alligators to connect the battery and to replace them after a while..
You can use a power supply, a solar system or a battery to power a station. I prefer to have 2 rechargeable lead batteries. If the station is always on duty, I change the battery everyday. So a small charger (900mA – 13.8 volts) might be useful. Don’t try a car battery charger.
Put your station in place and make an evaluation. Ask your visitors how they enjoyed, how you could improve the experience. Very young children wont appreciate but seniors might give you new quotes. It will be an iterative process!