# Phys 305 Experiment 2

Date: 2/23/2013

Experiment No.: 2

Title: Synthesis - A Square Wave, a Musical Note and Sound Cancellation Introduction: In this experiment, we will do three parts to find out the synthesis sound. They are a Square Wave, a Musical Note and Sound Cancellation. For the first part, it is the superposition of sine wave. We are going to construct a square wave (approximately) by adding together some pure tones of different frequencies. This stretched string vibrating at different frequencies at the same time. For the second part, we will do very similar as first part, but use the different frequency which is 196 Hz and its multiple times to create a music note from sine waves. For the third part, we do a sound cancellation experiment. We will understand the importance of phase in sounds by considering the amplitude. The concepts we will used in this experiment are followed: Fourier theorem: any periodic oscillation curve, with frequency f, can be broken up or analysed , into a set of simple sine curves with frequencies f, 2f, 3f, 4f, 5f… etc, each with its own amplitude. Conversely, adding together the set of sine curves will reconstruct, or synthesize, the original oscillation curve. Harmonics: a harmonic of a wave is a component frequency of the signal that is an integer multiple of the fundamental frequency. The combination of the fundamental and its harmonics is also periodic at the fundamental frequency. Overtone: a natural resonance of vibration frequency of a system. A harmonic is an overtone, but an overtone is not always a harmonic. Superposition of waves: stretched string vibrating at different frequencies at the same time. The pitch heard is fundamental frequency. The other frequencies heard are timbre. The Period of a vibration is the time it takes to go through one complete swing. The frequency is the number of complete swings it makes in one second. Frequency is also the inverse of the period. The frequency...

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