Should I use PZM-11 or PZM-11LL for voice recognition?
I’m installing a voice recognition system throughout a home that has been designed for an individual with cerebral palsy. I had intended to use the PZM-11 microphones but then found that mics are either line level (PZM-11LL) or mic level (PZM-11) adding confusion to the selection. Can you clarify the difference between line level and mic level for me and suggest which would be better in this application? The mics will be installed throughout the home.
Harry C. Lieb
Reply: Mic level is roughly 2 millivolts, and line level is roughly 1 volt. Microphones have a mic-level output, while most electronic devices have a line-level output. The PZM-11LL microphone has a built-in preamplifier that gives the mic a line-level output, which can plug directly into a VCR for security/surveillance recording.
Your application requires a microphone mixer, which is designed to accept mic-level signals from microphones. So I'd recommend the PZM-11 microphones for your application. They are mic level, so they can be plugged into a microphone mixer.
I'd also recommend an automatic (gated) mic mixer such as made by Shure. That mixer turns off all the mics except for the one being spoken into. This greatly reduces background noise, and helps the voice recognition system work better. The output of the mixer connects to a line input in a computer sound card for use with voice recognition software.
Here's a link to the Shure SCM810, which is an 8-channel automatic mixer for up to 8 microphones. Shure also makes a model SCM410 for up to 4 microphones.