Introduction to Perceptual Audio

The human auditory system consists of multiple components which influence our interpretation of sound.  To explore the nature of the human auditory system, we have created numerous demonstrations which allow a listener to explore various audio phenomena.  Exploring these phenomena separately using specialised examples allows the listener to understand some of the limitations of her own auditory system.  The examples provide insight as to how these limitations may be exploited for a variety of applications.

There are many areas of engineering which take advantage of the limitations of the human auditory system.  Formats such as MP3, popular for transferring audio files over the internet, is an example of a technology based on the limitations of the human auditory system.  MP3 works by looking for sounds the brain cannot detect, and removes them, greatly reducing the size of the audio file.

Another such application involves hiding information within an audio file, which is inaudible to a listener, but can be detected by a computer.  This hidden information, or "watermark", can be used for several applications. One application is the supervision of copyright materials, and their distribution.  If an artist records and distributes her songs, there is currently nothing preventing unauthorized copying and sharing of her music.  With digital watermarking technology, a special key can be hidden in each song, allowing only the user who has paid for the music to play it.  This watermarking technology can also be used to send other information about a song such as artist, track name, etc.  We have implemented watermarking technology and have created relevant examples to explain the process.