Documents Brainstorming   A procedure to generate alternative, producing many ideas in a short time span Life Cycle Assessment   Life-cycle assessment has emerged as a valuable decision-support tool.   SOUND WAVE and MUSIC The Nature of a Sound   The nature of sound as a longitudinal, mechanical pressure wave is explained and the properties of sound are discussed. Sound Properties and Their Perception   Sound has properties, such as pitch, frequency and intensity. The measure of intensity is the decibel scale.   Resonance and Standing Waves   Natural Frequency, Fundamental Frequency and Harmonics Musical Instruments   Resonance, Guitar Strings, Open-End Air Columns, Closed-End Air Columns   How Acoustic Guitars Work   The guitar is one of the most popular musical instruments in use today, and it spans a huge range of musical styles -- rock music, country music and flamenco music all use the same instrument to create wildly differ. Timbre   Timbre can be roughly defined as all those qualities of a sound that aren¡¯t just frequency or amplitud. Envelope and spectra are very large concepts, and include a lot of sub-categories.     Analog and Digital Recording   In order to understand how a CD works, you need to first understand how digital recording and playback works and the difference between analog and digital technologies. How MP3 Files Work   The MP3 movement is one of the most amazing phenomena that the music industry has ever seen. Unlike other movements -- for example, the introduction of the cassette tape or the CD -- the MP3 movement started not with the industry itself but with a huge audience of music lovers on the Internet.