Medical Transcription Philippines

About digital audio files

With the advent of multimedia computers (audio, video, etc.), more material is being generated in the form of digital computer files. Digital hand held dictation devices are now available that record to a memory card and can generate audio files you can place on disk or send over the Internet.

Some of the existing formats for digital audio files are:

• Windows PCM (WAV)
• MPEG3 FhG (MP3)
• 8-bit signed raw format (SAM)
• ACM waveform (WAV)
• CCITT mu-Law and A-Law (WAV)
• Dialogic ADPCM (VOX)
• IMA/DVI ADPCM (WAV)
• Video formats (AVI, MOV, etc.)
• Sony Memory Stick Voice (MSV)
• Sony Digital Voice File (DVF)
• Sony IC Recorder Sound (ICS)
• Olympus (DSS)
• MPEG audio (layers I and II)
• Microsoft ADPCM (WAV)
• Next/Sun CCITT mu-Law, A-Law and PCM (AU)
• Apple Quicktime
• Raw PCM Data
• Real Audio (RA, RAM, RMM, RM, etc.)
• SampleVision format (SMP)
• Sound Blaster voice file (VOC)
• TrueSpeech (WAV)
• DiamondWare Digitized (DWD)
• Apple AIFF (PCM encoded data only) (AIF)
• CD and DVD Audio Disks

Which files are the best to use? It depends on your situation and use of the digital audio file. If your equipment uses a particular audio file format, you have limited options.

Which type work on the Web and Internet? The web and Internet use of audio is evolving. Original sound files included the Next/Sun (AU extension) files and the also, due to Windows’ popularity, the WAV files. Later formats like Quicktime and Real Audio showed promise in reducing the file sizes and added ability to stream the audio. Streaming means the audio is played over your computer’s speakers pretty much it arrives.

Before that, the entire audio file had to be downloaded before it was played, which was inconvenient for large files or those that were transmitted in real time. Now MPEG3 files are popular for music files and are very good at compressing audio as are WAV type TrueSpeech files. The answer to the question really depends on what you are trying to do and what resources you have to provide the audio files to the user. Some issues include:

• How are you going to provide audio files to the users?
• Will the users be able to work with the audio files you provide?
• What bandwidth Internet connection do the users have?
• Are the files going to be downloaded or streamed?

How do you make the smallest audio files? This is a fairly technical issue that trades off sound quality with file size.

• Newer audio file technologies typically make smaller files.
• Some file formats (or options within a format) can reduce size.
• As the number of samples per second is decreased, so is the file size (usually).
• As the number of bits of resolution (dynamic range) per sample decrease, so does the file size (usually).

The process of decreasing the file size can be fairly complicated, and if not done properly can result in distorted or noisy audio files.

What things should be done to generate good audio files? The most important thing is to start with good quality audio — either digitally recorded or recorded on magnetic audio or video tape. Just like the guidance provided above about transcription, good quality recordings are essential at reducing cost and increasing the quality of your audio file. Fortunately digital audio files can be edited and enhanced more easily to produce a better recording from

What can be done with Audio files to edit the recording? Digital audio files can be easily edited to produce a good quality finished product. For this discussion, editing is the simple rearrangement of audio segments that is analogous to cutting and splicing audio tape. Some examples are:

• Audio can be easily deleted.
• Audio can be easily moved, copied, or spliced.
• Silence can be added or removed.
• Audio from other sources can be spliced into the recording.

What can be done with Audio files to enhance the recording? Digital audio files can be enhanced either to improve poor-quality sound or by adding various special effects.

• Uneven speaker volumes can be adjusted so low volume speakers can be heard.
• One speaker can be increased or decreased in volume to generate a sense of distance or depth.
• Many constant background noises (hum, buzz, noise, etc.) can be eliminated without distorting the speech.
• A large number of recording studio special effects can be added to all or parts of the recording.

source: www.type-thing.com