(sonicArts) more sound properties

To follow up on basic sound properties from a previous post, and to complete our review of chapter 2 in Hoskens, you should know these concepts.


In addition to the previous post which covered the frequency to pitch relationship, and how we measure frequency, you need to understand the concept of the period of a waveform. The period is the time it takes to complete one cycle of a sound wave, and is the inverse of the frequency.  If middle C has an approximate frequency of 262 Hz, then the period (represented at T) is T = 1/262, or .0038 seconds (3.8 ms).


You should know about the relationship between amplitude and loudness. Make sure you understand the decibels (dB) as they apply to measuring sound pressure levels, and the relationship between loudness and hearing damage.

The softest sound we can hear is given the measurement of 0 dB, and represents the threshold of hearing. At 120 dB we reach the threshold of pain. For every 6 dB increase in sound pressure level, there is a corresponding doubling of amplitude of the waveform.

Study the spl levels and time exposures in the tables on pp. 22 – 24.


I have not covered this topic in class, but it becomes very important as you work on your first concrete music project. Articulation refers to the change of loudness over time, and it is another perceptual property of sound. Articulation relates to the physical property of amplitude envelope.

Although we will not cover envelope types in depth until we start covering synthesis, it is useful to understand the basic envelope types of ADSR (attack-decay-sustain-release) and AR (attack-release).


Rhythm is a perceptual property relating to the organization of events happening in time. Anything that happens in time has rhythm, although people generally refer to the term with some hierarchical organization – beats and meter. Wishart refers to this type of hierarchy when he is talking about lattice music.


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