listener ratings; listenership
Used in broadcasting contexts to refer to the percentage or number of people listening to a radio program or station.
The listener ratings for that radio program have been declining year by year.
The listenership figures for the new program were announced.
視聴率 measures television (or streaming) audience share, while 聴取率 measures radio audience share specifically.
Compound of 聴取 (listening) and 率 (rate). The exact historical derivation is uncertain, but the term is a straightforward modern technical compound.