Music Technology and Education

Amplifying Musicality

Andrew Brown

• Publisher: Routledge
• Year: 2014
• ISBN:
  9781317934998
• Edition: 2
• Topic: Medien & darstellende Kunst
• Subtopic: Musik

Music Technology in Education lays out the principles of music technology and how they can be used to enhance musical teaching and learning in primary and secondary education. Previously published as Computers in Music Education, this second edition has been streamlined to focus on the needs of today's music education student. It has been completely updated to reflect mobile technologies, social networks, rich media environments, and other technological advances. Topics include:

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• Basic audio concepts and recording techniques

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• Enhanced music instruction with interactive systems, web-based media platforms, social networking, and musicianship software

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• Administration and management of technology resources

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• Distance education and flexible learning

Music Technology in Education provides a strong theoretical and philosophical framework for examining the use of technology in music education while outlining the tools and techniques for implementation in the classroom. Reflective Questions, Teaching Tips, and Suggested Tasks link technology with effective teaching practice. The companion website provides resources for deeper investigation into the topics covered in each chapter, and includes an annotated bibliography, website links, tutorials, and model projects.

section II Creation

three Sound Recording

DOI: 10.4324/9781315857862-3

Recording technologies have had the biggest impact on music making and learning in the last century. Since the emergence of digital recording in the middle of the twentieth century, digital technologies have become the dominant sound recording and distribution platforms. The range is vast: from voice recorder apps on smart phones to multi-track audio workstations and digital consoles in recording studios. Although different in scale, these devices make use of the same digital audio processes that allow seamless translation of audio data between devices and transmission over the Internet.

This chapter will introduce the basics of audio recording processes with a focus on digital audio capture and editing. It will also reflect on the opportunities for using audio recording technologies in educational contexts.

Elements of a Music Recording System

The sound recording process usually involves several pieces of equipment. Sometimes these are separate components, but especially in inexpensive setups they are integrated. It is important to become familiar with what each piece does, how it connects with the others, and how the sound signal flows through the system. A thorough understanding of signal flow will make problem solving much easier. There are several methods for learning about signal flow: practice in setting up and packing up a recording system, working with flow diagrams of various signal flow options, and talking-aloud the signal flow as it is traced from microphone to recording media and on to speakers for playback. Figure 3.1 shows a flow diagram that illustrates the main stages of the digital recording signal flow.

Most equipment and apps integrate these stages. Even so, it’s important to understand the data (signal) flow—the journey of a sound signal through the recording process and back to the listener. It’s difficult and frustrating trying to work out how a digital recording system operates or how to fix problems without understanding signal flow.

Figure 3.1 Digital audio signal flow in a simple digital recording system

Sound is captured by a microphone (or perhaps comes as a signal from a guitar or other electronic instrument) and is converted to digital data by an audio interface. This data is stored in the device’s memory for visualizing, editing, and playback. During playback the signal passes through various built-in plug-in effects that add equalization, reverberation, compression, and so on. When there are several tracks of audio, they are mixed with an appropriate volume balance and the tracks are positioned in space (panned), usually as a stereo image (two channel) or surround-sound plane (four or more channels). For playback, the audio interface also converts the data back to an electrical signal, which is then passed on to an amplifier and speakers (or headphones).

Operational difficulties with recording systems often come down to a kink in this signal pathway. The most productive method of solving these problems is to trace the signal as it makes its way along the (virtual) path until the problem is found.

Plugs and Connectors

There are a variety of analog and digital connections that can be used between hardware elements in a recording system. All-in-one devices, such as smartphones or tablet computers, include a built-in microphone and speaker and no hardware connections are required. However, the quality of these devices is often poor, and external microphone and speakers are often needed. External devices are connected either wirelessly or by cable. Common analog cable connectors, carrying very small electrical currents, are shown in Figure 3.2. One connector is the 3.5mm mini jack plug, used for output to headphone and audio input. Professional, external audio interfaces might use larger 1/4-inch jack plugs, like those used for connecting electric guitars; RCA plugs, often used for home hi-fi equipment; or XLR connectors, most often used on professional microphones.

Figure 3.2 Common audio connectors

Figure 3.3 Common digital connectors for audio devices

Common digital connectors for audio are shown in Figure 3.3 and include USB, FireWire, and Thunderbolt. Often an external audio interface will connect to these, exposing analog connectors for audio equipment. Microphones with direct USB connection, usually referred to as ‘USB microphones’, are now readily available, and there are also wireless speakers with no physical connectors that transmit audio over Wi-Fi or Bluetooth. There is further discussion of these connection options in Chapter 7. Less common these days are optical cables that use a dedicated port or sometimes a 3.5mm mini jack for digital audio connection.

Playback

The final stage in the digital audio signal flow is playback via loudspeakers. At this stage there are many choices of equipment, depending on the listening context, individual preferences and, of course, varying budgets. Playback quality is a critical factor at the end of the signal chain just as microphone selection is at the start. Generally, the variation in quality within digital processing devices is minimal, but quality differences in the analog domain (microphones, audio interfaces, and speakers) can be dramatic.

The two major categories of playback devices are loudspeakers, for public or shared listening contexts, and headphones, for personal playback. Both are necessary at different times and in different environments. In classrooms, loudspeakers allow for group listening and for sharing of music. The minimum requirement in most cases would be a pair of stereo speakers of reasonable quality; the capability for streaming music to them wirelessly from any digital device in the space (computer, tablet, and so on) would be an added convenience. Headphones in classrooms are useful for private listening, and headphone distribution amplifiers are useful for dividing one signal into several, allowing small groups to listen together without disrupting others in the space.

Microphones

The microphone is a critical element of the audio recording process. Microphones come in a bewildering array of sizes, shapes, and costs. Because they have such a dramatic impact on the quality of a recording, it is worth spending the time to become familiar with their basic operation and use.

Two venerable microphones are shown in Figure 3.4. First is the Shure SM58, a dynamic mic with cardioid pickup pattern. It is very popular for live sound and for recording drum kits. Second is the AKG C414, a large diaphragm condenser with multiple pickup patterns. Historically, it has been one of the most used studio microphones, quite versatile but especially renowned for use with acoustic instruments and vocals.

Dynamic and Condenser Pickups

Microphones operate by converting sound pressure patterns in the air into electrical signals. There are several ways to achieve this. Most microphones use a delicate diaphragm that moves in response to sound waves. Dynamic microphones convert this movement into electricity using a magnetic coil. Dynamic microphones are robust and relatively inexpensive and therefore are often used in live performance situations. Condenser microphones measure the change in distance (electrical capacitance) between the diaphragm and a fixed plate. Condenser microphones can be quite delicate and capable of high-fidelity recordings, and so they are frequently used in recording studio settings. Because they contain active electronic circuitry, condenser microphones need to be powered, either by a battery or by phantom power delivered via the microphone cable.

Figure 3.4 The Shure SM58 and AKG C414 microphones

Phantom Power

Phantom power is a method of delivering a small amount of electrical power through microphone cables. The current is transmitted through two of the three wires within a balanced audio cable. Typically these cables use XLR connectors. Phantom power supplies are often built into mixing desks and computer audio interfaces. Typically, phantom power can be switched on or off as required; for example, phantom power is turned off when using a dynamic microphone. A condenser microphone, however, will not work without being powered, and so phantom power must be available and turned on to avoid an otherwise subtle error in the recording setup. For devices with built-in microphones, like field recorders or mobile computers, power requirements will be managed automatically.

Diaphragm Size

Microphones, especially condensers, are classified according to the size of their diaphragms: either small or large diaphragm microphones, and some in between. The classic large-diaphragm microphones are associated with recording studios and radio or TV presentations. They are usually vertically oriented in design, with a flat side as the front. They often have multiple pickup patterns (see below) and are versatile enough to record almost anything.

Small-diaphragm microphones are also widely used. They are pencil-shaped and designed with one end as the front. The smaller diaphragms can be very responsive and are used when it is important to capture the sparkle in the sound; for example, with acoustic guitar and percussion, or as drum overheads. Because these microphones are small and lightweight and can be unobtrusively positioned, they are frequently used for concert recordings.

Some microphones might have more than one diaphragm. There are a number of reasons for this. Stereo microphones have two diaphragms to capture sound from different directions at the same time. Some use secondary diaphragms to manage the directional response by combining the signals from each diaphragm in particular ways.

Directional Response

Microphones are typically design to point in a certain direction, meaning that they have a front and a back to best pick up sound from one or more directions. However, the directional response of microphones can vary. There are three main types of polar (or pickup) patterns—types of directional response—in common use: omnidirectional, unidirectional, and bidirectional. These are depicted in Figure 3.5.

Omnidirectional microphones pick up sound from any direction. This pattern is often used in lapel mikes, for public speaking, and for ambient field recording. Unidirectional microphones pick up sound from in front and reject sound from the sides or from behind. They have a heart-shaped pattern (see Figure 3.5b), which is often referred to as cardioid. This is the most common pattern used for dynamic microphones and is particularly useful on stage where sound from surrounding instruments needs to be excluded. Bidirectional microphones pick up sound equally from the front and back and less effectively from the sides. Because of its characteristic polar shape, the bidirectional pattern is so...