Alan Anderson, School of Arts and Social Sciences, School of Commerce and Management, Southern Cross University, Lismore, NSW, 2480. alan.anderson@scu.edu.au
Recent advances in consumer grade software for digital audio recording, editing and distribution over the Web have opened the way for its use in various fields of education and training. Nevertheless, educators without prior training or experience of audio production can find it challenging to make 'optimum' use of this technology. In the worst-case scenario, education institutions risk the proliferation of a casual approach to the operation of Voice over Internet Protocol (VoIP) communication and a 'shovel ware' approach to the uploading and distribution of shoddily produced audio content that fails to meet the quality standards upheld for traditional print-based and A/V resources. Both have significant implications for student learning and satisfaction. An abundance of 'Do It Yourself'' Webcast, VoIP and Podcast Web sites offer advice to enthusiasts, businesses, community groups and educators. However, close examination of a sample revealed a lack of due emphasis on fundamental production skills, whilst the significance of using quality equipment is frequently understated. Raising awareness of such issues is important amid increasing use of convergent VoIP and audio-enhanced Web-based instruction. Moreover, previous studies have identified poor quality audio as a factor that contributes to miscommunication and disruption of learning.
Recent advances in consumer grade technology for digital audio recording, editing and delivery over the Web have paved the way for its application in various fields of education and training. However, for educators without prior training or experience of audio production it can be challenging to make 'optimum' use of this new "Do It Yourself" (DIY) technology. Adding to the confusion for those seeking self-help is the variable quality of advice given in DIY Web casting, Podcasting and VoIP Web sites. Informed by analysis of these Web sites, professional audio and Web-based learning literature, this paper aims to highlight the importance of educators and students learning how to optimise sound quality in the context of audio-enhanced Web-based instruction. This is significant because previous studies have identified poor quality audio as a factor that has contributed to miscommunication and disruption of learning.
Previous studies have concluded that poor quality audio is a factor that contributes to miscommunication and disruption of learning. Neal and Miller (2006) state the most problematic "issue with effective audio conferencing is quality, since students are generally intolerant of poor quality audio." Mitchell, Clayton, Gower Barr and Bright (2005) identify similar issues underlying the reluctance of New Zealand Polytechnic teachers to fully embrace audio conferencing technologies. Whilst, in relation to cross-cultural communication issues, Mullen, Jackson, Anderson et. al. (2002, p.17) note that because "non-native speakers cannot compensate for poor audio to the same degree as native speakers, it is likely that they will require higher audio quality than first language speakers. To a lesser extent, they add, "unfamiliar accents may have the same quality requirements (ibid)."
Similar conclusions about the consequences of poor audio quality in hybrid CD-ROM and Web-based educational media packages. Researchers, Liaw, Kennedy, Keppell, Marty and McNair (2000) asked a cohort of medical students to comment on the use of such a package in an open text response. Students responses were generally positive, however, 29 of the 110 participants commented "the audio was too soft or unclear." This response was also reflected in a number of students (21) commenting that the poor "audio quality was one of the worst aspects of the package." The researchers acknowledge that "technical difficulties were experienced with volume control when the package was installed on computers in the computer lab." Further, that "students may have had difficulties hearing the audio for one of three reasons: their headphones were plugged into the wrong audio socket, the sound control software was set too low, or the mute button was on. Students were often not experienced enough with the computers to rectify this situation on their own (ibid)." Clearly, this study serves as a reminder for education providers to place due emphasis on checking that appropriate equipment is installed and functioning correctly. Further, that students and teachers need adequate training on how to rectify such minor problems as they arise. Finally, the mastering of audio tracks for video learning objects needs to be done properly to ensure ample playback volume (head-room) on a variety of speaker systems and earphones without undue distortion.
Webcasting is a term used generally to describe use of the Web for delivering live or recorded versions of audio or video broadcasts [HREF1]. "Podcasting is distinct from other types of online media delivery because of its subscription model, which uses a feed (such as RSS or Atom) to deliver an enclosed file. Podcasting enables independent producers to create self-published, syndicated 'radio shows,' while listeners may subscribe to feeds using 'podcasting' software (a type of aggregator), which periodically checks for and downloads new content automatically"[HREF2][HREF3].
Podcasting of lecture content is on the increase in education institutions worldwide. Morales and Moses (2006) claim that "Podcasting has revolutionized education and particularly higher education by enabling up-to-date content, addressing multiple intelligences and allowing for the anytime/anywhere delivery of instructional content." Stanford University "offers audio lecture content, but also offers videos of their sports activities." Meanwhile in the Television industry, "NBC makes available an audio recording of its evening news via a podcast, however, without interpretation of the visual components (ibid)." Whilst enthusiastic about the potential of educational Podcasting, Morales & Moses (2006) suggest the NBC approach is not a particularly good one for educators to follow because class lectures run the risk of being incomplete if only the audio recording of a visual learning resource-oriented lecture is provided as a podcast. They add that many institutions are establishing studios where "podcast-calibre content can be produced both by faculty and students because, "although not particularly difficult, the process is cumbersome enough to to prevent some from adopting the technology into their curriculums." [HREF4]. Stone and Moller (2005) make a similar point in regard to the newspaper business, commenting that "even though the equipment and software needed is simple and inexpensive, the publisher must have the right people, skill and time to produce podcast content."
Production of audio content can be quite time-consuming if a lot of editing is required in preparation for Webcast. The need for judicious editing is clear in Myer and Clark's (2003) assertion that poor quality audio can be distracting and disruptive to learning, particularly if the lecture content or voice-over explanation is not ideally structured and longer than need be. Conveniently, even 'free-to-download' software such as Audacity™, enables one to cut, paste and rearrange content into a logically sequenced and coherent whole, minus any redundant or unduly repetitive content. The more time spent editing, the more proficient one becomes at using the software. This can pay dividends in time saved whilst allowing the DIY producer-lecturer to retain complete editorial control.
There are technical as well as pedagogical benefits to be gained from judicious editing out of non-essential material. A shorter duration recording results in a smaller file size which can be downloaded faster and requires less storage space [HREF5]. Steward (2007) [HREF6] notes that “many webmasters like the idea of adding background music to their web sites” but most are put off by concerns about “slow loading pages and large file sizes.” These concerns are valid, especially for computer users with older computers and dial-up access to the Internet [HREF7] (W3C, 2007) [HREF8]. However, there are various ways to add sound to a Web site while keeping file sizes to a minimum. With a program that can create Flash files, one can import WAV or MP3 files and then create small files from these sounds that will load automatically on a Web site (Steward, 2007) [HREF9]. As is the case with editing, file conversion and compression should be done judiciously because it can have negative implications for sound quality as frequencies at the upper and lower extremes of what most humans can hear are discarded [HREF10]. For example, reducing a multichannel stereo recording of music to mono is sometimes done to help economise on file size but this can result in losing the effect of hearing particular instruments or sounds (that were panned to extreme right or extreme left in the mix) coming where they should in the original full stereo image (ibid). Perception of depth may also be lost without hearing the full stereo image, irrespective of whether one plays back through two speakers (White, 2002, p. 41).
Many Podcast enthusiasts seem almost fanatical in their approach to get others involved. In their enthusiasm to explain how affordable and easy Podcasting is, the relevance of using higher quality audio equipment and software is often understated on their Web sites and forums [HREF11][HREF12].
"The good news is you don’t need an expensive microphone. The one I’m using costs less then ten bucks at Wally world" [HREF13].
Numerous Web sites examined during the preparation of this paper echoed this sentiment. Meanwhile, critics of poor audio quality are equally quick to remind Podcasters that there are minimum standards of equipment that can be used if the intention is to produce good quality sound recordings that help to retain rather than put off an audience. MacComas (2006) argues that some Podcasts are literally painful to listen to:"when I listen very long to a poor audio quality podcast it gives me a headache, hurts my ears and wears me out" [HREF14]. Clearly, this is not the kind of response educators would be hoping for in student feedback on Podcast lecture content. The Shure corporation, manufacturers of professional audio equipment, note: "some podcasts sound like professional radio talk shows, while others are clearly put together in someone’s basement" (Shure, 2007) [HREF15]. Whilst Jackson (2006) states:
"If your computer has a microphone, you could start recording your podcast right now. Don't. The microphones that come with computers -- either those built into today's laptops or those bundled with desktop computers -- don't sound very good. Buy a real microphone, either a USB microphone like Samson's $80 C01U USB Studio Condenser Microphone or a professional vocal microphone from a company such as M-Audio, Sennheiser, or Shure" [HREF16].
Jackson adds that a professional microphone will require an audio interface and a pop-filter (screen) in front of the microphone is recommended to cut down on popping consonants. The preamp componentry of the audio interface functions to amplify a low level signal to line-level. Jackson, Shure and MacComas focus on equipment issues, recommending in particular the use of appropriately high quality microphones. They also emphasise optimum positioning and handling of microphones to maximise capture of wanted sound and minimise the capture of unwanted sound [HREF17].
In a demonstration training video of 'Elluminate live™' [HREF18], the presenter seems to be making an occasional adjustment to her headset microphone, resulting in several 'clunk' sounds along with frequent breath-sounds and pops. Assuming this is how these extraneous noises were generated, some of the clunks could have been averted by the presenter avoiding any non-essential contact with the conductive components of the headset. In addition, better positioning of the microphone might have helped to reduce the breathing sounds and pops. Many online learners are likely to wear a headset microphone and earphones so any extraneous sounds will be localized in their ears. Although in this case the clunk sounds are not very loud or frequent, it is worth considering that a less experienced presenter with little experience of using microphones could inadvertently create even more noise if they do not pay due attention to their microphone technique. Moreover, presenters need to be aware that a sudden audio spike of sufficiently high amplitude can be harmful to the ears (Hunt, 2005 in Audiology News, 2007) [HREF19].
Fortunately, Elluminate and other Web conferencing and VoIP service providers generally have audio streaming processors that compress, de-ess, equalize, and peak-limit transients [HREF20].
This technology helps to decrease the intensity of unexpected clunks, pops and 'sssss,' shhhh and 'ttttt' sounds [HREF21] [HREF22]. The effect of audio stream buffering can be heard in the changing pitch of the previously mentioned Elluminate presenter’s voice. The presenter rightly explains why this happens at the beginning of the presentation but as mentioned previously in relation to Mullen, Jackson, Anderson et. al. (2002, p.17) the changing of pitch combined with other extraneous noises could prove distracting for some students if the instructor or other students were to make a habit of adjusting their headset or related audio cables while speaking.
Obviously audio quality issues that relate to network architecture and signal processing are beyond the control of end users. Nonetheless, teachers and students can do much to optimise the quality of the sound they broadcast, receive and hear on playback by learning to configure optimise settings on their computer software, audio interface, microphone and playback monitors (speakers). In contrast to this ideal, Liaw, Kennedy and Keppell et. al (2000) identified a number of minor technical issues that apparently disrupted learning for some students yet could easily have been rectified by students with quite basic computer audio skills. The problems included: headphones plugged into the wrong audio socket; the sound control software set too low or the mute button on. Learning to to troubleshoot when such minor technical issues arise has obvious benefits in terms of avoiding delays or disruption to learning. Furthermore, learning to install and optimise settings on any external audio equipment and software from the outset enables the user to confidently set up their home computer to study off-campus or to use any available lab computer without fear of things having been left in a state of array by the previous user.
Understanding how feedback noise occurs (and how to control it) is another example of 'need-to-know' knowledge for the audio enhanced Web-based learning environment. The 'squealing sound' of feedback is sometimes heard coming from a Public Address (PA) system due to poor handling or positioning of the microphone by a presenter with little awareness of feedback issues (ibid). The “Zen Audio Project”- team at Simon Fraser University explain the generation of a feedback loop as follows: "Sound picked up by the microphone is amplified and sent to the loudspeakers and back into the room where it is again picked up by the microphone, further amplified, and so on, leading quickly to an infinite amplification loop and a loud squealing sound. Feedback is loud, annoying and potentially dangerous to ears” [HREF23]. Feedback can also occur in a personal computer Web conferencing or recording environment, for instance, if an external microphone is held facing into (or at the wrong angle in close proximity to) the computer's active speakers. For personal computer-based conferencing, Shure (2006) recommends using a headset microphone and earphones to eliminate echo and feedback from speakers and to increase mobility. For Laptop computers with a built-in microphone, a set of earphones plugged into the laptop’s headphone jack is recommended [HREF24].
In order to go beyond a simple surface learning of computer audio do's and don't's, it is useful to study how different types of computer audio equipment work. Appendix 1 (figures 1 and 2) provide such information on different types of microphone and their suitability for different applications. In addition, understanding precisely how the technology works can help users to fully comprehend the importance of correct microphone technique (White, 2002, p. 34). For example, Cardioid-pattern headset microphones (fig. 1) are useful for people who must move around while speaking. However, contact with conductive components can cause extra noise and “the wide frequency response of capacitor microphones can tend to emphasise sibilance (a whistling sound accompanying S and T sounds) in a person’s voice” (White, 2002, p. 34). Although de-esser signal processing can be applied to reduce sibilance, a better solution might be to use a less-bright capacitor model or a suitable dynamic microphone. The limited frequency response of the dynamic microphone will tend to minimize the problem [HREF25]. Finally, if mobility and proximity to loud unwanted sound sources is not a concern, a professional unidirectional microphone on a stand with a pop shield (to reduce breath sounds and popping consonants) is likely to sound better still (Jackson, 2006; White, 2002). The latter is likely to be essential for educators aiming to produce very high quality audio content for Webcast or perhaps to create an archive of their best lectures for later release on CD or DVD.
Not all factors contributing to poor audio quality in Web-based learning and Web conferencing environments lay beyond the control of individual students and teachers. With appropriate training and computer-audio knowledge, students and teachers can do much to optimise their audio-enhanced experience. Previous studies have shown this ideal is not always met and disruption to learning has occurred as a result of poor audio quality. Digital audio knowledge and skills will become increasingly important for online teachers and students in the very near future. First, because the integration of VoIP technology into Web-based learning environments is useful for educators aiming to conduct highly interactive tutorials with verbal discussion in Web-based environments such as Elluminate Live, Blackboard-WebCT and the like [HREF26][HREF27][HREF28]. Secondly, the educational benefits of Podcasting instructional audio and video content has captured the attention of individual educators and education providers world wide. Whilst flexible delivery teams or specialist centers in some institutions now offer a service to record and Podcast lectures, many educators may prefer to learn the necessary skills and do much of the editing and uploading of content themselves, thus retaining greater control over when, where and how their instructional material is presented. Others whom prefer to delegate these tasks can better communicate their specific requirements through greater awareness of the skills and equipment required to achieve and maintain credible standards in the context of audio-enhanced Web-based instruction.
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Appendix: 1:
Microphones have a polar pattern also known as a pickup pattern. Understanding how particular patterns enable a microphone to receive sound from a particular direction (and range) while rejecting sound from another direction is important in order to understand:
| Pick up pattern | Characteristics |
| Omnidirectional | Picks up sound equally well from all directions. |
| Cardioid |
Picks up soundmostly from the front in the heart-shape part of the diagram. |
| Figure of Eight | Picks up sound from the front and rear but not the sides. |
Figure 1. Three commonly used microphone pick up patterns and their characteristics
| Microphone Type | How the technology works | Common uses |
| Dynamic | A diaphragm is coupled to a coil of fine wire. The coil is mounted in the air gap of a magnet, free to move about within the gap. As the diaphragm moves in response to acoustical energy (varying waves of pressure called sound waves) the coil moves within the magnetic field, thereby inducing a small electrical current. | Live concert and studio applications for vocal or musical instruments. Most live vocal microphones such as the industry-standard ‘Shure™SM58’ are dynamic microphones. |
| Condenser - also known as a capacitor microphone | A gold plated plastic diaphragm, mounted above a conductive back plate, separated by a small volume of air, form an electrical component called a capacitor. Phantom power is applied to the diaphragm. As the diaphragm vibrates in response to sound waves, the electrical charge it induces in the back plate changes proportionally, and produces an electrical representation of the diaphragm [HREF20]. | Headset microphones such as the Sony ECM-310BMP, telephones, tape recorders, hearing aids, live and recorded audio engineering, radio, television and in computers for recording voice. High quality studio microphones such as the MILAB VIP 50 [HREF22], and the Neumann U87 Ai, a large dual diaphragm condenser microphone with selectable directional patterns: omnidirectional, cardioid and figure-8 [HREF24 ]. |
| Electret Condenser | The diaphragms is permanently charged in the manufacturing process and retains a static charge indefinitely. It requires no external polarizing voltage but does require external phantom power (or an internal battery) for the internal amplifier to buffer the high impedance condenser capsule output from the relatively lower impedance of the mic input [HREF25]. | Mobile phones, lapel microphones, movie camera microphones such as the Sony ECM-44BMP Omnidirectional Miniature electret condenser lavaliere [HREF27]. |
Figure 2. Common types of microphone and the uses to which they are suited (adapted from Shure, 2007 [HREF], Microphone Madness, 2007 [HREF18] and Kelly Industries, 2007 [HREF].