RESOURCESINTECHNOLOGY hat is music? Why is one Technology of Music person's music just "noise" to someone else? What are the different ways music is produced? Why do different musical James Flowers instruments malze different sounds? Whether or not a sound is musical can be a subjective judgement. In general, "musical sounds are those which are smooth, regular, pleasant and of definite pitch. Unmusical sounds are rough, irregular, unpleasant, and of no definite pitch" (Wood, 1975, p. 1). However, this distinction is only approximate. But what is sound? Simply put, sound is a vibration. When a violin string vibrates, it makes the front and back wooden plates of the violin vibrate. These plates make the air vibrate. A series of longitudinal pressure waves passes through the air to the ears. The alternating higher and lower pressure of these waves make the eardrums vibrate and sound is heard. F&we 1. Computer screen from Pe@ormeF sojhvare. (Courtesy of Mark of the Unicorn.@) The science of sound is called acoustics. There are many areas and applications of acoustics. Musical acoustics is the science of musical sounds. Architectural acoustics is concerned with the behavior of sound in and around structures. SONAR (Sound NAvigation Ranging) can detect the presence of submarines. Ultrasonics refers to the use of sound waves that are too high pitched for us to hear. Among the many uses of ultrasonics is its ability to produce a picture of a developing fetus. Unlike X-rays, ultrasound does not pose a radiation hazard. Nearly all areas of acoustics involve the same basic areas: sound propagation, sound transmission and sound reception. Music is a form of communication. It begins with the musician (sender) using an instrument (encoder) to produce a series of sounds (coded message). The sounds are transmitted fi-om one place to another through the air (channel). A listener (receiver) uses his or her ear (decoder) to make sense of the sounds. As with other art forms, the decoded message is not necessarily the same message that the musician intended to transmit. This can work to our advantage; the same piece of music can make us feel different each time we hear it. Most musical sounds have three basic characteristics: pitch, loudness and timbre. Pitch refers to how high or low we perceive a note to be. Loudness is our impression of the strength of the sound. Timbre is the "color" of a sound. A bamboo flute and an electric guitar may be able to each play a note of the same pitch and loudness, bet the two notes sound different due to their timbre. There have been recent advances in musical technology. Most of these concern the electronic manipulation of musical information. Historically, musical technology has primarily involved the instruments used to make music. After briefly classifying musical instruments, there will be examination some relatively new musical technologies and a closer look at what sound is. Contemporary Analysis Musical Instruments Musical instruments can be separated into five different classifications (Campbell and Created, 1988): ideophones, Figure 2. S&nal prnduced @om an ADSR unit in a music yntbesizer. Signal amplitude (vertical) is membranophones, chordophones, plotted a~ainsttime (horizontal). Wave 1 is a trianplar carrier wave uith the amplitude envelnpe shoivn aerophones and electrophones. in 2. A = attack time; D = initial decay time; S =sustain level; and R = release time. Ideophones include rattles, xylophones, thumb pianos, jaw harps, gongs and triangles. They all produce sounds without the application of additional tension, unlike drum skins and strings. The materials making up thesc instruments have natural direc~onalshift in air determines the pitch vibrating element, but is not capable of tonal properties. A membranophone we hear. The sound produced is called an adequate acoustic amplification. These produces sound with a skin or membrane. edgetone. Another type of aerophone, instruments rely on electronic amplification. Usually, the membrane is stretched over an which includes oboes, clarinets and A solid-body electric guitar is an example; opening and is struck. Drums produce saxophones, uses flexible cane reeds that without electronic amplification, these sound this way. However, a kazoo is a vibrate at a frequency based on the size of guitars are very quiet. membranophone that works by blowing air the column of air in the instrument. A third type of electrophone relies solely across a membrane. Chordophones, such The fifth classification of musical on electronics to synthetically produce (or as violins, guitars and pianos, use vibrating instrument is the electrophone. synthesize) and amplify sounds. This means strings to produce sounds. However, a Electrophones produce electronically that we can create new, "unnatural" vibrating string is not very loud. In order to amplified sounds. There are three types of sounds. Robert Moog and Donald Buchla increase the volume (amplitude) of the electrophones. The first type relies on an separately developed the first commercial sound, each of these instruments has a acoustic (i.e., non-electronic) production of synthesizers around 1966 (Elsea, 1990). soundboard made out of wood. The the original sound. An acoustic guitar is These synthesizers use voltage-controlled soundboard is carefully manufactured, capable (as a chordophone) of producing oscillators, amplifiers and filters to produce usually out of a piece of spruce that has very sounds independently of electronic sound. Greater control over the sounds is straight grain. Special attention is given to amplification. However, by putting a small made possible with an ADSR envelope the thickness of the soundboard and the transducer or a microphone on an acoustic generator. This allows a musician to placement of braces. Braces stiffen certain customize the attack time (A), the initial areas of a soundboard; they divide a guitar, we can change the guitar into an soundboard into smaller sections. Each of acoustic-electric guitar. Preamps can be decay time (D), the sustain level (S) and the these smaller sections is of a proper size to used to modify the signals from these release time (R) (see Figure 2). resonate when a certain tone is produced. transducers before they reach an electronic The different areas of a soundboard amplifier. Some of these preamps are small Advances in Acoustic Musical respond diikrently depending on the enough for bass players and guitarists to clip Technology Throughout our history, frequency of a string's vibrations. onto their belts. Typically, they allow a people have been inventing and changing Aerophones produce sound with a musician to make rough adjustments to the musical instruments. Ovation Guitars vibrating column of air. A flute produces a different frequency ranges (bass, midrange produced the Roundback, a guitar with a very clear sound. One type of aerophone, and treble). The signal from these molded plastic body. However, certain which includes flutes and whistles, produces transducers can also be mixed with a instruments reached a plateau in their very clear sounds directing a continuous microphone's signal. The user can evolution many years ago. The violin, for stream of air against a sharp edge, splitting separately adjust gain, bass, treble and phase example, has not changed significantly in the stream of air. If the angle and air control for the separate signals and for the hundreds of years. In fact, many luthiers velocity are just right, the air will tend to go mixed signal. (i.e., stringed instrument makers) today try first to one side, then to another, in a A second type of electrophone is an as best they can to copy very old violins, rhythmic fashion. The kequency of this instrument that produces sound with a such as those made by Stradivari. But this does not mean that musical technology has Advances in Electronic Musical must be aware of the abilities of all their stood still for those instruments. Technology equipment in order to produce the desired Technology has bccn used to find out what Hooking together many electronic musical sounds. makes a fine violin sound so pleasing. devices on a stage or in a recording studio Electronically encoded MIDI messages Researchers have studied wood anatomy in can be very complicated. In the past, if you pass along a cable kom one de\rice ' to relation to violin tone (Bond, 1976), wanted to attach one brand of keyboard to another. There are sixteen independent acoustical effects of violin varnish another manufacturer's controller and a channels in that cable. If the sender and (Schelleng, 1968) and the tuning of violin third manufacturer's speaker system, you receiver are on the same channel, they can plates. were often out of luck. Different communicate. Cables that connect MIDI manufacturers had different configurations Joseph Nagyvary (1988) examined the devices plug into three different types of on their products-some devices just could wood in old violins. He found that the MIDI ports: In, Out and Thru. All three not communicate with other devices. To wood in some eighteenth century violins ports accept a round, 5-pin jack, but they overcome this problem, a protocol or made by Antonio Stradivari and other serve different functions. An "In" port standard was developed in the early 1980's. master luthiers contained two items not It is the Musical Instrument Digital allows a device to receive MIDl normally found in present day instruments: Interface, abbreviated MIDI (O'Donnell, information. After processing, information high salt concentrations and evidence of 1991 ). Now, devices that use MIDI can is output through the "Out" port. The microbes. No doubt, the logs used to make communicate with one another. third type of port, "Thru," outputs a these old violins were transported or stored MIDI is not audio information. It is a duplicate of the information coming into in salt water.