Recording your answering machine greeting

The leading cause of unnecessary answering machine returns is customer disappointment with the sound quality of the greeting. In many cases, this problem can be solved by varying how you record your greeting. Below, I give step-by-step instructions for recording the best-sounding greeting. Then, for the those of you who are interested, some of the engineering background behind the recording process.

How to produce a clear recording

How it all works

Signal to Noise Ratio: This is a measurement of the amount of useful information a signal contains versus the amount of non-useable noise. This concept is critical to understanding the limits of your answering machine with respect to recording a clear-sounding greeting.

AVC - Automatic Volume Control: Your answering machine's greeting record function uses an automatic volume control (AVC) to regulate the sensitivity of the recording process to try to compensate for variations in the volume of your voice as you do the recording. Unfortunately, the AVC's limitations are easily exceeded if your voice is too loud or too close to the microphone or too soft or too far away from the microphone.

The microphone: Inside each answering machine is a tiny crystal microphone (usually concealed behind a small hole near the front edge of the machine). This crystal employs a property known as piezoelectricity to produce an electric current whenever the crystal vibrates. When sound strikes this microphone, the crystal vibrates in a fashion that varies as the sound varies and it produces a tiny electrical current that also varies with the sound. But, like the AVC circuit discussed above, the crystal has limits on its ability to faithfully reproduce sounds that are either too quiet or too loud.

Too close/too loud: If you are too close or speak too loudly, the sound waves from your voice overwhelm the microphone and/or the AVC, producing a sound that is fuzzy and garbled because the crystal is vibrating too hard and producing electrical currents that are not in perfect alignment with your voice; signal to noise ration drops quickly in this situation, due to noise being added by the crystal itself.

Too far/too quiet: If you are too far away or speak too softly, the sound waves from your voice may be inadequate to vibrate the crystal consistently and may also cause the AVC to "strain" to hear you. This results in a recording that sounds faint, uneven, and with background noise picked up by the AVC; signal to noise ratio increases because of noises picked up from the room and also because noise always present in the electrical circuit itself becomes significant if the voice is too quiet.