I'm trying to use the SHHS database for developing a breathing rate based sleep stage prediction model.
I've came across the fact that many of the recordings edfs have both "AIRFLOW" and "NEW AIR" signals, and some have just "NEW AIR" or "New Air" signals.
What is this "NEW AIR" signal? and does "AIRFLOW" signal indicate nasal or oral airflow?
I've looked through all the documentation but could not find an answer to this, does anyone know?
Hello. There were multiple names used for the airflow signal as described under the SENSORS section at https://sleepdata.org/datasets/shhs/pages/08-equipment-shhs1.md. Here is the info from that page:
Thermistry/Thermocouple: The original Compumedics triple thermister a Y shaped chassis with nasal and oral bead sensors, used for the first few months of the study connected to the side of the PIB using a lemo connector and used Channel 12 named “Airflow” on the collection montage. The Compumedics thermister was uncomfortable and replaced with ProTech thermister M325. This thermister used the "auxiliary" channel as designated on the PIB (Channel 17). Sites were asked to modify the montage and name Channel 17 “New Air” so scorers would be able to tell when Compumedic thermister was used versus the Protech thermister. Instructions were sent to the sites on how to modify the collection montage (add channel 17). It took several attempts for some sites to correctly name this channel and modify the montage. As a result, some studies have this channel 17 named: “NEW AIR”, “NEWAIR”, “AIRFLOW”, “airflow”, "new A/F", "New Air" and/or “AUX.”
The signals you mention all represent combined nasal and oral airflow, as both of the devices referenced (Compumedics and ProTech) had sensors that measured temperature change at the nose and in front of the mouth.
I hope this is helpful, and please let us know if you have additional questions.