Audio conference data may travel over what transport mediums?
ISDN, IP, POTS
An audio conference usually includes what, besides mics?
Line or acoustic echo-cancellation
Audio conferences pic up sounds how
A single POD (mic and speaker) or individual mics.
The subjective perception of sound is...
Loudness. (yes, poorly worded question)
a base 10 logarithmic relationship of a power ratio between two numbers
Decibels can be used for what?
Voltage (V), distance, sound pressure (SPL), power (W).
Threshold of hearing (dB)
Very quiet room (dB)
30 dB (.00063 Pa)
Office cubicle (dB)
Normal conversation (dB)
85 dB (.355 Pa)
Rock concert (dB)
130 dB (63 Pa)
Smallest dB change a human can hear
Smallest noticeable volume change (dB)
A _________ dB change is subjectively twice or half as loud.
If you increase the power (W) by 5dB how much will the loudness (SPL) increase?
5 dB! dB changes in distance, voltage, or power will result in the same dB change in SPL
dB reference levels: 0 dB SPL =
dB reference levels: 0 dBV =
1 V (consumer electronics)
dB reference levels: 0 dBu =
.775 V (ProAV electronics)
dB reference levels: 0 dBW =
dB reference levels: 0 dBm =
.001W or 1 mW