Sound files
High quality stereo sound files may appear to be the perfect way to communicate with your customers, but you must remember that these files will be played over a telephone line which has only 8 KHz bandwidth. Most of the higher frequencies are lost when a recording is played over the telephone.
When you record sound files:
Record monaural rather than stereo.
Use 16 bit-depth A-to-D conversion.
Use a quality audio editing program to normalize the amplitude of your various phrases and convert to mu-LAW or A-LAW PCM.
When you have finished recording, listen to each recording in its final format. If you use the above guidelines, the way they sound at this point will be very close to how they sound over the telephone.
