Integrating Technology in the Foreign Language Classroom

Incorporating sound in a presentation or WWW page involves preparing the original sound and digitizing it in an appropriate format.  Because we tend to be visually oriented, sound production can be harder to do well than visual production, so you'll probably need to spend more time on it that you might think.

Sound fills the air all around us, and our ear is working all the time to filter out unimportant sound from our consciousness so we can pay attention to the important information. This means that we are largely unaware of how much sound surrounds us at all times.  If you concentrate on what you hear, you will find that silence is very hard to find.  A microphone does not have an intelligent filter, so it will pick up everything (depending on how sensitive it is).  By carefully preparing your recording environment, you can eliminate a lot of the background noise that might otherwise spoil your soundtrack.  Getting a clean recording at the outset will mean less work trying to fix problems later.

Your microphone should be suited to your recording equipment and to the sort of recording you are doing. Poor quality equipment or a noisy environment will introduce noise into your recording, interfering with the signal that you are trying to capture. An omni-directional mic picks up sound from all directions and is good for recording background noise, music from several directions, or several people talking.  A uni-directional mic is pointed at the sound coming from a single source - one speaker, one instrument, etc.  Clip-on mics can do a great job recording individuals in conversations because they are placed so close to the sound source, but if you have more than one or two participants, you may need to think about mixing sounds from multiple mics to control different sound levels.  Table mics are nice for several people sitting around a table but will pick up the sound of someone touching or bumping into the table, so subjects need to take care if you use these.  Microphones that are built-in to a tape recorder or camcorder tend to pick up machine vibrations from motors (more noise) and are difficult to place close enough to a subject. A long microphone cable may act as an antenna that could pick up static from fluorescent lighting or even a local radio station.

If a microphone's specifications include "signal to noise ratio", a high signal to noise ratio will sound best. Another way to improve your microphone's sound is to use a pre-amp (see below).

Sound is made when objects vibrate producing pressure waves that can be picked up by our ears. These waves can be captured when they vibrate the membrane of a microphone and can be re-created by the amplified vibrations of the membrane in a speaker.  If we graph the intensity of this wave or of the motion of the microphone membrane over time, we will get a smooth waveform curve in which the frequency of a sound is the number of peaks per second (Hertz = cycles per second).  The distance between two peaks is the wavelength.  As with most physical properties (e.g. temperature, pressure, velocity, the shape of the groove of an LP), this is an analog signal. In other words, between any two moments in time we might make infinite number of different measurements of intensity, between any two points on the scale there can be an infinite number of different values. Although the graph shown below is very simple, waveforms (a graph of intensity) can be quite complex because many different frequencies are usually present simultaneously (a spectral graph will show the distribution of frequencies in a sound).
When we store the signal in a computer, we need to represent the analog signal by a digital approximation that we can think of as a series of numbers measuring samples of the height of the analog curve.  Computers by their nature can only have space for a limited number of measurements (not infinite) and each value can have a precision limited by the space (number of bytes) allotted to each number (Consider the difference in measuring something on a scale of 1 to 10 vs. a scale of 1 to 1000000). In this way a series of numbers can be used to produce a signal that approximates the original analog signal, but it can never but truly the same. The more numbers you have (sampling rate in kHz) and the more precise those number are (resolution of each sample in bits), the more the digital sound will resemble the original, but the larger your sound files will be. A digital waveform can never be completely smooth.
The advantages of digital recordings are that the sound can be manipulated computationally, there is no degradation from an original to a copy, and the signal can be sent for long distances over telecommunications links without picking up noise. The disadvantage of digital representation is that it is always just an approximation of the real sound (though the approximation may be so close that our ears can't hear the difference).

The sound card in a computer can create sound, process sound from input sources, and send sound to output destinations. A sound recorder may capture sound from a microphone (mic in) or from an audio device (line in).  It is possible to control which source will be used by opening the entertainment accessory called volume control (start / all programs / accessories / entertainment).  This utility controls the output or playback volume of a number of devices (microphone, line in, CD audio, midi, wave, etc.).

 


By resetting the options/properties from playback to recording, the input source (mic, line in, CD, midi) may be selected.  If you are recording from a microphone, you may need to check that the mic is selected here, that the mic volume is adequate but not too loud, and, perhaps if needed, that the microphone is boosted (under Advanced properties). You have to play with it to see what works for your current recording conditions.
 

Pre-Amp: The quality of microphone inputs can vary enormously from one computer to another. If you need better quality recording from a microphone, it may be worth investing in a pre-amplifier that will amplify the microphone input. This gives you more control over strength of the signal that your computer receives. The sound card in your computer probably has a pretty cheap amplifier for the microphone. A pre-amp will do a better job boosting the microphone's signal. The output from the pre-amp would then be plugged into the computer's line-in jack (rather than the microphone input jack). When using a pre-amp, you may need to be careful of clipping in both the pre-amp and the sound card.

Sound Recorder

The simplest way to make a recording using Windows' built-in tools is to open the entertainment accessory, (start / all programs / accessories / entertainment) Sound Recorder. Click on the red recording dot to begin.  Save the file in .WAV format using File / Save, and be sure to select File / New to begin another recording from scratch.  Under the menu (Edit / Audio Properties / Customize) it is possible to select a particular frequency and resolution other than the old default 22,050 Hz 8 bit mono.  The best frequency and resolution are always a tradeoff between quality and size.  Music is more demanding than voice. We recommend using at least 22,000 Hz 16 bit for voice recording for projects in this class. However, we really do NOT recommend using Sound Recorder at all. You can download free software that is infinitely better.

  

	AU Samples
	44,000 Hz  16 bit 110 KB	44,000 Hz  8 bit 90 KB
	22,000 Hz  16 bit 61 KB	22,000 Hz  8 bit 45 KB
	8,000 Hz  16 bit 16 KB	8,000 Hz  8 bit 13 KB

A much greater degree of control and more extensive features for manipulating sound files are available in sophisticated sound applications such as Cool Edit 2000 (currently in our lab), Cool Edit Pro (now Adobe Audition), and Sound Forge.  The main features needed are selecting and cropping a sound as you might a photo, normalizing a sound as you might adjust the brightness of a photo, and saving the sound in a variety of formats commonly supported by multimedia applications and WWW browsers.

 

The Edit / Trim menu will crop (or trim) a selected portion of the sound.  File / Save as... offers a wide variety of options including .AU .WAV, .RA (RealAudio), and .Mp3. Mp3 format is widely accessible and uses an excellent compression CODEC (compression-decompression) to make file size smaller while maintaining very good sound quality.

Audacity

Audacity is a high quality, free sound editing program that has all the features you are likely to need. http://audacity.sourceforge.net/

 

Sound editing will be covered in a later lesson.

There are also other low cost programs available for sound editing that will do a fine job for most of your needs.

Sound Advice: 10 Tips for Better Audio Gathering:
http://www.videomaker.com/article/9426/

Recording Tutorial:
http://www.xaudiotools.com/html/recording_tutorial.html

Equipment for Audio Recording of Speech:
http://www.phon.ucl.ac.uk/resource/audio/recording.html

Sensitivity of the Human Ear:
http://hyperphysics.phy-astr.gsu.edu/hbase/sound/earsens.html

16 bit and 24 bit audio:
http://www.tweakheadz.com/16_vs_24_bit_audio.htm

Sound recording: Microphones:
http://www.hrelp.org/archive/advice/microphones.html

A Primer on Microphone Preamps:
http://www.tweakheadz.com/microphone_preamps.htm

RECORD YOUR OWN RADIO DOCUMENTARY:
http://www.soundportraits.org/education/how_to_record/