首楞嚴義疏注經 1.92

1.92

佛聲和雅，眾所愛樂，聽之無厭，如迦陵頻伽在於㲉鳴勝餘鳥故，堪喻佛聲。此鳥非常，故云仙也。遍十方界者，顯其圓義。如來梵音，於諸相中最為勝故，如別處說。

The Buddha's voice is gentle and harmonious, loved and delighted in by all, heard without satiety; just as the kalaviṅka crying while still in the egg shell surpasses other birds, it is fit to serve as a metaphor for the Buddha's voice. This bird is extraordinary, hence it is called "immortal." "Pervaded the realms of the ten directions" reveals its perfect meaning. The Tathāgata's brahma-voice is the most superior among all the marks, as explained in other places.