I’ve written about the NPR Labs elevated FM IBOC power tests conducted in Rhode Island, Minnesota and Texas; This week I was able to learn more details of the mobile listening tests conducted outside Baltimore over a two-week period that ended just last week. During that time, NPR Labs conducted 48 listening sessions with 24 participants.
The participants heard audio clips collected from the test stations in the field transmitted at –10 dB, –14 db and –20 dB; they rated the audio quality with a push button device while listening in cars traveling at 35 and 60 mph, and gave the audio ratings of “bad,” “poor,” “fair,” “good” or “excellent.”
Seventeen different cars were assessed to play audio clips in with the Nissan Altima chosen as the most consistent performing, average sedan acoustic enviornment.
The audio clips were played in :15 cuts divided into format categories such as male and female speech. The cuts were collected during the earlier field tests in Rhode Island, Minnesota, Texas and Colorado.
Off-duty police officers drove the cars so the test participants could concentrate on the audio.