Audio Recording & Compression Tips
1) What is Analog and Digital sound?
Analog sound can well be defined as sound that is generated by a Gramophone record and an Audio cassette, a Digital sound is what one hears on Compact Discs, Mini Discs and DVDs. The sound heard on Internet or on a Computer also is in a Digital format.
2) What is the audio format required for speech-to-text conversion?
The audio files can be in Analog or Digital formats for Speech-to-Text conversion, but Digital format is the preferred choice, because the audio recordings can be sent on the internet using the File Transfer Protocol feature on our website, an audio recording which is in analogue format (audio cassette) will have to be mailed to us.
3) How to record Skype interviews for transcriptions?
If you are using the Skype to interview a co-host, it is required by the co-host also to use the Skype, and to record the interview a voice recording software called HotRecorder will have to be downloaded and installed, this software is compatible with VOIP applications such as Skype and Google Talk, the voice recordings are saved in an ELP formatwhich can be converted into a .wav, OGG and an MP3 format. (The HotRecorder can be downloaded from www.hotrecorder.com )
4) How are telephone interviews or teleconferences recorded for soliciting a transcript?
Telephone Interviews and Tele-Conferences can be recorded using a customized adapter which is attached to the hand-set of a wired telephone, the two ways conversation can be recorded on to a portable recorder or to a computer with a sound card.
The interviews can also recorded using a cell phone, however the telephone adapters are different for wireless telephones including a cell phone, the adapter is attached between the ear piece jack and the headset plug-in which available with a cell phone. These telephone voice recording accessories are available at.
5) Which microphones should one use for recording audio?
There are two different kinds of microphones that are commonly used for recording audio, one is the Omni directional and the other one is directional (a.k.a cardioid). The omni-directional microphones pick up surrounding sound from all directions and are not recommended
The directional microphone does not pick background noise; it only picks sound that comes from a direction, thus eliminating extraneous noise. The built-in microphones that available in equipment are of inferior quality and therefore should be used as a last resort.
6) Which is an ideal position of placing a microphone to record interviews?
The microphone should be placed as close as possible to the person being interviewed, microphones should be placed 2 feet way from the speakers and pointed directly towards them, the Inverse-Square methodology under which most microphones function lower the audibility of the sound if it is placed at a distance.
7) Does one have to compress large audio recordings for uploading them online?
The audio files do not need to be compressed if they are uploaded on our website, but if large audio files are sent as attachments by email then they will need to be compressed to fewer than 10MB a file.
8) How to compress audio files that are sent as email attachments?
If a Windows application is used for recording audio
CLICK Start > Programs > Accessories > Entertainment or Multimedia > Sound Recorder > Sound Recorder will appear
> Click the recording button on the Sound Recorder (red dot) to start the recording
(If headsets are used for recording, make sure the microphone is positioned correctly)
> After the recording is complete, click the stop button (square button)
> Open the File in the Menu of the Sound recorder and click Properties
> Click Convert Now – in the Properties
> On the Attributes list, click on the arrow on the right
Choose 22,050 KHz and 16 Bit, Mono from amongst the drop-down options displayed Click OK.
( Note: The 8 Bit Option should not be chosen, as it may not be compatible with the Compression Software listed below.)
> Click OK to close the Properties
> Choose Save as in the File Menu and label it.
(The saved file will be in a .wav format)
The audio files can also be compressed in an MP3 format, compression software known as SCMPX that is compatible to work in Windows can be downloaded from a Japanese website site http://www.din.or.jp/~ch3/index_e.html choice of language options are available on the Japanese website, an .exe program known as MPEG Audio Player Converter can be downloaded.
After it has been downloaded
> Click on the SCMPX shortcut icon on the Desktop
> Click on the Convert option, a choice to choose Single Files or Multiple Files for compression will be displayed, choose the Single File.
> Select the option Encoding MPX
> Choose the .wav file to be compressed the SCMPX will open the Encoder
> Change the Encoder bit rate setting to 128000 and allow the options to be on the Default settings.
> Click OK
> The audio file will be compressed and a second copy in the MP3 format will be created, which will be 10 times smaller than a .wav file.
Note: If an audio recording is of 60 second duration the space occupied on the Hard Drive will be 2.5 MB, to reduce the size of the files for sending them as standard sized 10MB Email attachments audio compression is required, however if the Files are uploaded on our website Audio Compression is not required.