Arch 498C - Responsive Environments Tech Report — Sensing Sound Doaa Alsharif | Dana Lee | Virginia Bradbury SOUND IN GENERAL Sounds are waves of pressure formed from mechanical vibrations traveling through a medium of liquid, solid or gas. These pressure can be produced by any vibrating objects. When these vibrations hit our ears a specific nerve cells are stimulated to pass electrical signals to the brain which will cause the experience of hearing. Wavelength, frequency, and velocity are the characteristics that defines sound. Sound Sensors: Sound sensors sense any audible or inaudible sounds to human ears. They are detected through microphones or specialized transceivers. The challenges for these sensors is to separate meaningful sounds from inconsequential sounds. Sound Detector: SparkFun sound detector is an audio sensing board with three different outputs. The Sound Detector not only provides an audio output, but also a binary indication of the presence of sound, and an analog representation of its amplitude. The 3 outputs are simultaneous and independent, so you can use as many or as few as you want at once. It costs $10.95 at SparkFun $7.95 at AdaFruit. Voice Recognition: EasyVR 3.0 is a multi-purpose speech recognition module designed to add versatile, robust and cost effective speech and voice recognition capabilities to virtually any application. It costs $49.95. HYDROPHONES Hydrophones are devices that can detect underwater sounds through the use of piezoelectric transducers, which produce electric current when a mechanical force is applied. Because the transducers change their shape when a force (like a sound wave) is applied, they can convert the produced energy into electric current when a sound is detected. Advantages: - Waterproof - Do not require a power source - Inexpensive - Very accurate - Ranges up to 50 miles Disadvantages: - Cannot distinguish between multiple objects - Cannot distinguish between natural vs. artificial noise - Needs another device to detect, record, or transmit the findings Circuitry: MICROPHONES Thinking about bending and sound, instruments are a great example of that. For example, wind instruments that use a reed, rely on the bending back and forth of a reed when they blow into the mouth piece to create tones by using that vibration. In our modern day, we even have electronic wind instruments, aka wind synthesizers/wind controllers. Although they are played like a normal wind instrument, no sound is actually produced. They usually use breath as volume control. Converts electrical signals to a synthesizer that converts the signals into audio signals that can be played through speakers. Applications: Most devices that sense sound use a microphone of some type. For example, a clap on/off flight looks for a sudden, short, strong sound. The controller can be set to trigger if the sound is higher than a normal set threshold. Microphone are transducers that sense and convert sound waves into electrical energy using a diaphragm, where the sound waves bend the diaphragm. Speakers also work in a similar way. Microphones detect that by allowing a diaphragm to move, which causes other components in the microphone to vibrate. These vibrations are converted into an electrical current which becomes the audio signal.. How? Early mics compressed graphite powder (I think) which changed resistance within the powder, and we can measure voltage change with the Arduino.... References: http://www.electronics-tutorials.ws/io/io_8.html https://www.sparkfun.com/products/12642 http://www.tech-faq.com/hydrophone.html http://www.fleetsubmarine.com/sonar.html http://www.exfac.com/aussie_bray/hydro_circuits.htm