Re-visiting the measurement of the Speed of Sound in Air

Sound is a form of energy, and it can be represented visually. Sound is represented by waves, and waves have measurable quantities such as frequency, wavelength, and speed. Measuring the speed of sound in air is among the experiments conducted in introductory physics laboratory courses. Purpose of this re-visit is to improve accuracy with the use of current technologies in data collection. In the classic resonance-tube method, a tuning fork of known frequency and adjustable water level with a reservoir can (or other means) are used and the resonance condition is obtained by hearing the sound when it is loud. Instead, a speaker driven by a function generator and a sound sensor can be employed for more accurate results, where the resonance condition is obtained by means of the FFT display of the sound sensor. In addition, the sound sensor can be used in the echo method and the time for echo is measured using the data collection software. The temperature, air-column resonance, and echo methods have all been tested to determine the speed of sound in the air. While all methods resulted in similar results, some methods can become more complicated to execute. Ensuring the proper conditions is important for good results. Accepted value is obtained using temperature, gas constant and ratio of specific heats and average molar mass for air, which is comparable within 1-2% of the measured values of the speed of sound in air.