Archive for November 2nd, 2008

The first audio we will look at recording is a talking file. We will then look at recording or adding a music file.

Preparation

In making recordings, the goal is always to get a clear, undistorted speech signal with as little noise as possible.

Noise that will detract from or ruin signal quality for acoustic analysis can include:

* Any kind of environmental noise

* Speaker movement, especially if movement impacts the microphone or an object close to the microphone

* Voice overlap between speakers

* Noise from the computer system during transfer to computer

The best way to minimize environmental noise is to record in a sound-proofed or sound-treated room. To reduce the effects of noise in an ordinary room:

* Choose a quiet location

* Cover large reverberant surfaces with blankets or cloths

* Unplug electrical appliances

* Close doors and windows

* Turn off lights and fans or air conditioning

* Remove anything that ticks, buzzes, bangs, rattles, squeaks, hisses, or otherwise makes itself heard

* Always make a one minute black recording to see if there are any noises you have missed.

* Make sure you log off any software application like chat programs etc. There is nothing worse than almost getting to the end of your recording and your mail or chat program pipes in with a ding or what ever.

When recording speech form texts it is usually possible to satisfy all, or most of the above conditions. However, to record speech in “natural” situations, speakers often must be allowed to move around and interact with other people, with objects, or with their surroundings. This makes it substantially more difficult to get optimal recording quality.

How to create your audio files using Audacity!

Click here for the live flash movie. (broadband)

This tutorial will help you produce all types of sound files. The first thing you will need is a recording program. Audacity is cross-platform – it runs on Windows (98 through XP), Mac OS 9, Mac OS X, and many Unix platforms, including Linux. Audacity is a free audio editor. You can record sounds, play sounds, import and export WAV, AIFF, and MP3 files, and more.

Use it to edit your sounds using Cut, Copy and Paste (with unlimited Undo), mix tracks together, or apply effects to your recordings. It also has a built-in amplitude envelope editor, a customizable spectrogram mode and a frequency analysis window for audio analysis applications. Built-in effects include Bass Boost, Wahwah, and Noise Removal, and it also supports VST plug-in effects.

• Audacity is free and the source code is available under the GNU General Public License.
  .
• No limits on the number of tracks or the length of any track, except the size of your hard disk. .
• Import almost anything: WAV, AIFF, Next/AU, IRCAM, MP3, and MIDI files are supported natively, but Audacity will also open just about any uncompressed sound file and automatically deduce the format (using the Import Raw Data… feature).
  .
• Audacity not only includes many high-quality effects built-in, but also lets you use plug-in effects in the industry-standard VST format. There are dozens of free, shareware, and commercial VST plug-ins online that do everything from Reverb to Noise Reduction.

• Audacity acts like a non-destructive editor , providing multiple levels of undo, but it also writes changes made to the audio to disk, eliminating the need for complicated real-time processing. .

• Label tracks allow you to annotate waveforms (for example, transcribing speech) and later export the waveforms to a text file. .

• Powerful spectral features allow you to view waveforms as spectrograms or plot the power spectrum of any region of audio, and even export this data to a spreadsheet.

Here is a complete tutorial for Audacity.

How Can I Record Myself? The first thing you need is a microphone or some kind of input device. Most multimedia computers come with a microphone, but you can also pick one up from any computer or music store. The microphone can be plugged in directly to the sound card in your computer. Most sound cards use a 1/8" Walkman-type headphone jack, so make sure your microphone is compatible with this. What are the steps of recording? Here is a quick step-by-step guide to recording yourself:

• Before you start you recording write down what you want to say. When you are recording speak slowly and concisely.
• Plug your microphone into the mic input in your sound card
• Open up your audio recorder/editor and put it into record mode
• Check the input levels to make sure the signal is loud enough, but not too loud.
• Hit "record" and start speaking
• When youre finished, hit "stop"
• Depending on the software you use save it as .wav or .mp3 file
• If your audio application supports editing, you can remove any unwanted sections

 

Once you have finished and if your software did not allow you to save as a mp3 or wav, you can use an MP3 encoder to convert your sound file to MP3 format. WAV and AIFF files run about 10MB per 1 minute of CD-quality audio, and converting to MP3 can reduce this by a factor of 12. For some background about MP3, check out our MP3 tutorial. What are the steps of converting my sound file to MP3 format? Heres the remaining steps to convert your audio file to MP3 format:

• Open your MP3 encoding application
• Choose the "Convert" function
• Choose the WAV of AIFF file you want to convert to MP3
• Choose the sampling rate and bit depth of the MP3. This is usually 44.1 kHZ and 128 bits, and will result in compression by a factor of 12.
• When you are finished converting, add a title and other background info to the MP3 track using the track editor.