Monday, July 1, 2013

2013 Abstract- Comparing the Sound Fidelity of Different Sound Compression Methods

As personal listening devices have drastically proliferated in recent years, compressing audio files has become a ubiquitous process in order to save space. Although compressing can be beneficial, many compression methods can result in a loss of sound quality. The goal of this project was to determine which audio format has the highest sound fidelity. 

Sound fidelity is the measure of how accurately a compression method is able to reproduce the original uncompressed audio file. In this experiment, two lossless methods, .flac and .ape (Monkey’s Audio), and four lossy methods, .mp3, .wma, .ogg, .aac, were compared for sound fidelity. To test the different audio formats, different WAV files containing sine waves, square waves, and complex waves were created and obtained. WAV is an uncompressed audio format and is the baseline in this experiment. The WAV file was then compressed to audio formats listed above in four different bit rates (32,64,128,256 kbps) to ensure a comprehensive analysis of audio formats. These audio files were then opened in a program called NCH WavePad Sound Editor which possessed an FFT function and allowed for the conduction of a spectrum analysis, which determines the magnitude at each frequency in a certain audio signal. The spectrum analysis chart of each format was compared to the spectrum analysis of the WAV file. The more similarity that existed between the two charts, the higher the sound fidelity was of that format. 

The significance of this project is that it displays that other formats exist that have higher fidelity than MP3 while also having a smaller file size. This means that we can reduce our hard drives’ power consumption and carbon footprint while maintaining sound quality. 

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