This is a fairly conservative level of enhancement, and you can try values greater than 100% to get a more aggressive enhancement, but at the risk of introducing artifacts. The default setting is "100% spectral subtraction" this subtracts 100% of the quietest spectral slice from every frame. If the audio recording has significant amounts of background noise, you may like to try and clean the recording using Tools|Speech|Process|Signal enhancement. If you choose link, then the SFS file simply "points" to the WAV file so that it may be processed by SFS programs, but it is not copied (this means that if the WAV file is deleted or moved SFS will report an error).įigure 1.2 - SFSWin open WAV file dialog Preparing the signal
If you choose copy, then the contents of the audio recording are copied into the SFS file. In this latter case, you will be offered a choice to "Copy contents" or "Link to file" to the WAV file. If the file is recorded in plain PCM format in a WAV audio file, you can also just open the file with File|Open. If you choose to acquire your recording into a file using some other program, or if it is already in an audio file, choose Item|Import|Speech rather than Item|Record to load the recording into SFS.
It is usually not necessary to choose a rate faster than 22050 samples/sec for speech signals. Sampling rate, at least 16000 samples/sec is recommended. To acquire a signal using SFSWin, choose File|New, then Item|Record. In particular, microphone inputs on PCs are commonly very noisy. Only do this if you know that your audio input is of good quality, since many PCs have rather poor quality audio inputs. You can use the SFSWin program to record directly from the audio input signal on your computer. Acquiring and Chunking the audio signal Acquiring the signal