Physiologic Metronome Team Members: Ben Fleming, Cole Drifka, and Jeff Theisen Clients: Dr. Bill Fahl and Vanessa Young Advisor: Prof. Paul Thompson Abstract Final Design Testing Our group set out to design a metronome which uses a tactile pulse instead of an aural stimulus to provide rhythmic information to the practicing musician. The idea came from our client, Vanessa Young, a harp player and current graduate student at Carnegie Mellon University. The final design consists of an electronic metronome that outputs to a solenoid which delivers the tactile stimulus via an ear attachment. Testing demonstrated sufficient battery life and relatively accurate tempo indication. Figure 3 Output voltage versus time with the potentiometer set at (a) 100 beats per minute (actual tempo: 99.8 bpm); (b) 60 bpm (58.1 bpm); and (c) 40 bpm (38.0 bpm) Background A metronome is a device that provides a regular tempo for playing a musical piece [1] The first mechanical metronome was patented by Johann Malzel in 1816 [1] Modern metronomes are mostly electronic and typically use a small speaker to produce a constant, audible sound to maintain the tempo Battery Life: Using a standard 9V battery, the circuit was connected and ran continuously at the highest tempo setting for approximately 16 hours. Accuracy and Reliability: The metronome appears to give fairly accurate tempo outputs. Based on the tick mark/potentiometer scheme, the output appeared to be accurate within 2-3 beats per minute (Figure 3). Figure 1 The final prototype of the metronome. Both the case and the solenoid-containing ear attachment are shown. Motivation Problems with existing devices (i.e. conventional, audible metronomes): Using an audible tempo-maintenance mechanism, such as a small speaker, can make it difficult to distinguish the speaker’s sound from the music being played Most conventional metronomes do not employ tactile stimuli to maintain the tempo, while such tactile stimuli facilitate the internalization of the rhythm for the musician while she plays her instrument Future Work Further testing of the device by practicing musicians Digital display of the selected tempo (in lieu of tick marks) Using buttons to select the tempo instead of a knob/potentiometer Improve accuracy of tempo settings Possible multiple-metronome synchronization system Figure 2 The final circuit schematic. Adapted from [2]. Key Features of the Final Design (Figure 1): The case, which contains the perf-board-mounted circuit (Figure 2) The knob/potentiometer, which protrudes from the case and is used to adjust the tempo The tick marks, which indicate the selected tempo The ear attachment/solenoid, which delivers a nearly inaudible, concise tactile stimulus to the user Total Cost: $61.57 Client Requirements An essentially inaudible tempo-maintaining mechanism is to be employed in the metronome device The metronome device should be portable Accurate and reliable maintenance of the tempo by the metronome device $100 budget References [1] Metronome. (2009). In Columbia Electronic Encyclopedia. Retrieved from http://www.encyclopedia.com/topic/metronome.aspx [2] Metronome circuit schematic. (2009). Electronic circuits. http://electroschematics.com/216/electronic-metronome-circuit-schematic/